7. Render Pass

A render pass represents a collection of attachments, subpasses, and dependencies between the subpasses, and describes how the attachments are used over the course of the subpasses. The use of a render pass in a command buffer is a render pass instance.

Render passes are represented by VkRenderPass handles:

VK_DEFINE_NON_DISPATCHABLE_HANDLE(VkRenderPass)

An attachment description describes the properties of an attachment including its format, sample count, and how its contents are treated at the beginning and end of each render pass instance.

A subpass represents a phase of rendering that reads and writes a subset of the attachments in a render pass. Rendering commands are recorded into a particular subpass of a render pass instance.

A subpass description describes the subset of attachments that is involved in the execution of a subpass. Each subpass can read from some attachments as input attachments, write to some as color attachments or depth/stencil attachments, and perform multisample resolve operations to resolve attachments. A subpass description can also include a set of preserve attachments, which are attachments that are not read or written by the subpass but whose contents must be preserved throughout the subpass.

A subpass uses an attachment if the attachment is a color, depth/stencil, resolve, or input attachment for that subpass (as determined by the pColorAttachments, pDepthStencilAttachment, pResolveAttachments, and pInputAttachments members of VkSubpassDescription, respectively). A subpass does not use an attachment if that attachment is preserved by the subpass. The first use of an attachment is in the lowest numbered subpass that uses that attachment. Similarly, the last use of an attachment is in the highest numbered subpass that uses that attachment.

The subpasses in a render pass all render to the same dimensions, and fragments for pixel (x,y,layer) in one subpass can only read attachment contents written by previous subpasses at that same (x,y,layer) location.

Note

By describing a complete set of subpasses in advance, render passes provide the implementation an opportunity to optimize the storage and transfer of attachment data between subpasses.

In practice, this means that subpasses with a simple framebuffer-space dependency may be merged into a single tiled rendering pass, keeping the attachment data on-chip for the duration of a render pass instance. However, it is also quite common for a render pass to only contain a single subpass.

Subpass dependencies describe execution and memory dependencies between subpasses.

A subpass dependency chain is a sequence of subpass dependencies in a render pass, where the source subpass of each subpass dependency (after the first) equals the destination subpass of the previous dependency.

Execution of subpasses may overlap or execute out of order with regards to other subpasses, unless otherwise enforced by an execution dependency. Each subpass only respects submission order for commands recorded in the same subpass, and the vkCmdBeginRenderPass and vkCmdEndRenderPass commands that delimit the render pass - commands within other subpasses are not included. This affects most other implicit ordering guarantees.

A render pass describes the structure of subpasses and attachments independent of any specific image views for the attachments. The specific image views that will be used for the attachments, and their dimensions, are specified in VkFramebuffer objects. Framebuffers are created with respect to a specific render pass that the framebuffer is compatible with (see Render Pass Compatibility). Collectively, a render pass and a framebuffer define the complete render target state for one or more subpasses as well as the algorithmic dependencies between the subpasses.

The various pipeline stages of the drawing commands for a given subpass may execute concurrently and/or out of order, both within and across drawing commands, whilst still respecting pipeline order. However for a given (x,y,layer,sample) sample location, certain per-sample operations are performed in rasterization order.

7.1. Render Pass Creation

To create a render pass, call:

VkResult vkCreateRenderPass(
    VkDevice                                    device,
    const VkRenderPassCreateInfo*               pCreateInfo,
    const VkAllocationCallbacks*                pAllocator,
    VkRenderPass*                               pRenderPass);
  • device is the logical device that creates the render pass.

  • pCreateInfo is a pointer to an instance of the VkRenderPassCreateInfo structure that describes the parameters of the render pass.

  • pAllocator controls host memory allocation as described in the Memory Allocation chapter.

  • pRenderPass points to a VkRenderPass handle in which the resulting render pass object is returned.

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • pCreateInfo must be a valid pointer to a valid VkRenderPassCreateInfo structure

  • If pAllocator is not NULL, pAllocator must be a valid pointer to a valid VkAllocationCallbacks structure

  • pRenderPass must be a valid pointer to a VkRenderPass handle

Return Codes
Success
  • VK_SUCCESS

Failure
  • VK_ERROR_OUT_OF_HOST_MEMORY

  • VK_ERROR_OUT_OF_DEVICE_MEMORY

The VkRenderPassCreateInfo structure is defined as:

typedef struct VkRenderPassCreateInfo {
    VkStructureType                   sType;
    const void*                       pNext;
    VkRenderPassCreateFlags           flags;
    uint32_t                          attachmentCount;
    const VkAttachmentDescription*    pAttachments;
    uint32_t                          subpassCount;
    const VkSubpassDescription*       pSubpasses;
    uint32_t                          dependencyCount;
    const VkSubpassDependency*        pDependencies;
} VkRenderPassCreateInfo;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • flags is reserved for future use.

  • attachmentCount is the number of attachments used by this render pass, or zero indicating no attachments. Attachments are referred to by zero-based indices in the range [0,attachmentCount).

  • pAttachments points to an array of attachmentCount number of VkAttachmentDescription structures describing properties of the attachments, or NULL if attachmentCount is zero.

  • subpassCount is the number of subpasses to create for this render pass. Subpasses are referred to by zero-based indices in the range [0,subpassCount). A render pass must have at least one subpass.

  • pSubpasses points to an array of subpassCount number of VkSubpassDescription structures describing properties of the subpasses.

  • dependencyCount is the number of dependencies between pairs of subpasses, or zero indicating no dependencies.

  • pDependencies points to an array of dependencyCount number of VkSubpassDependency structures describing dependencies between pairs of subpasses, or NULL if dependencyCount is zero.

Valid Usage
  • If any two subpasses operate on attachments with overlapping ranges of the same VkDeviceMemory object, and at least one subpass writes to that area of VkDeviceMemory, a subpass dependency must be included (either directly or via some intermediate subpasses) between them

  • If the attachment member of any element of pInputAttachments, pColorAttachments, pResolveAttachments or pDepthStencilAttachment, or the attachment indexed by any element of pPreserveAttachments in any element of pSubpasses is bound to a range of a VkDeviceMemory object that overlaps with any other attachment in any subpass (including the same subpass), the VkAttachmentDescription structures describing them must include VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT in flags

  • If the attachment member of any element of pInputAttachments, pColorAttachments, pResolveAttachments or pDepthStencilAttachment, or any element of pPreserveAttachments in any element of pSubpasses is not VK_ATTACHMENT_UNUSED, it must be less than attachmentCount

  • The value of each element of the pPreserveAttachments member in each element of pSubpasses must not be VK_ATTACHMENT_UNUSED

  • For any member of pAttachments with a loadOp equal to VK_ATTACHMENT_LOAD_OP_CLEAR, the first use of that attachment must not specify a layout equal to VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL or VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL.

  • For any member of pAttachments with a loadOp equal to VK_ATTACHMENT_LOAD_OP_CLEAR, the first use of that attachment must not specify a layout equal to VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMAL.

  • For any member of pAttachments with a stencilLoadOp equal to VK_ATTACHMENT_LOAD_OP_CLEAR, the first use of that attachment must not specify a layout equal to VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_OPTIMAL.

  • If the pNext chain includes an instance of VkRenderPassInputAttachmentAspectCreateInfo, the subpass member of each element of its pAspectReferences member must be less than subpassCount

  • If the pNext chain includes an instance of VkRenderPassInputAttachmentAspectCreateInfo, the inputAttachmentIndex member of each element of its pAspectReferences member must be less than the value of inputAttachmentCount in the member of pSubpasses identified by its subpass member

  • If the pNext chain includes an instance of VkRenderPassInputAttachmentAspectCreateInfo, the aspectMask member of any element of pAspectReferences must only include aspects that are present in images of the format of the input attachment specified by the subpass and inputAttachment of the same element of pAspectReferences

  • If the pNext chain includes an instance of VkRenderPassMultiviewCreateInfo, and its subpassCount member is not zero, that member must be equal to the value of subpassCount

  • If the pNext chain includes an instance of VkRenderPassMultiviewCreateInfo, if its dependencyCount member is not zero, it must be equal to dependencyCount

  • If the pNext chain includes an instance of VkRenderPassMultiviewCreateInfo, for each non-zero element of pViewOffsets, the srcSubpass and dstSubpass members of pDependencies at the same index must not be equal

  • For any element of pDependencies, if the srcSubpass is not VK_SUBPASS_EXTERNAL, all stage flags included in the srcStageMask member of that dependency must be a pipeline stage supported by the pipeline identified by the pipelineBindPoint member of the source subpass.

  • For any element of pDependencies, if the dstSubpass is not VK_SUBPASS_EXTERNAL, all stage flags included in the dstStageMask member of that dependency must be a pipeline stage supported by the pipeline identified by the pipelineBindPoint member of the source subpass.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO

  • Each pNext member of any structure (including this one) in the pNext chain must be either NULL or a pointer to a valid instance of VkRenderPassInputAttachmentAspectCreateInfo or VkRenderPassMultiviewCreateInfo

  • Each sType member in the pNext chain must be unique

  • flags must be 0

  • If attachmentCount is not 0, pAttachments must be a valid pointer to an array of attachmentCount valid VkAttachmentDescription structures

  • pSubpasses must be a valid pointer to an array of subpassCount valid VkSubpassDescription structures

  • If dependencyCount is not 0, pDependencies must be a valid pointer to an array of dependencyCount valid VkSubpassDependency structures

  • subpassCount must be greater than 0

typedef VkFlags VkRenderPassCreateFlags;

VkRenderPassCreateFlags is a bitmask type for setting a mask, but is currently reserved for future use.

If the VkRenderPassCreateInfo::pNext chain includes a VkRenderPassMultiviewCreateInfo structure, then that structure includes an array of view masks, view offsets, and correlation masks for the render pass.

The VkRenderPassMultiviewCreateInfo structure is defined as:

typedef struct VkRenderPassMultiviewCreateInfo {
    VkStructureType    sType;
    const void*        pNext;
    uint32_t           subpassCount;
    const uint32_t*    pViewMasks;
    uint32_t           dependencyCount;
    const int32_t*     pViewOffsets;
    uint32_t           correlationMaskCount;
    const uint32_t*    pCorrelationMasks;
} VkRenderPassMultiviewCreateInfo;

or the equivalent

typedef VkRenderPassMultiviewCreateInfo VkRenderPassMultiviewCreateInfoKHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • subpassCount is zero or is the number of subpasses in the render pass.

  • pViewMasks points to an array of subpassCount number of view masks, where each mask is a bitfield of view indices describing which views rendering is broadcast to in each subpass, when multiview is enabled. If subpassCount is zero, each view mask is treated as zero.

  • dependencyCount is zero or the number of dependencies in the render pass.

  • pViewOffsets points to an array of dependencyCount view offsets, one for each dependency. If dependencyCount is zero, each dependency’s view offset is treated as zero. Each view offset controls which views in the source subpass the views in the destination subpass depend on.

  • correlationMaskCount is zero or a number of correlation masks.

  • pCorrelationMasks is an array of view masks indicating sets of views that may be more efficient to render concurrently.

When a subpass uses a non-zero view mask, multiview functionality is considered to be enabled. Multiview is all-or-nothing for a render pass - that is, either all subpasses must have a non-zero view mask (though some subpasses may have only one view) or all must be zero. Multiview causes all drawing and clear commands in the subpass to behave as if they were broadcast to each view, where a view is represented by one layer of the framebuffer attachments. All draws and clears are broadcast to each view index whose bit is set in the view mask. The view index is provided in the ViewIndex shader input variable, and color, depth/stencil, and input attachments all read/write the layer of the framebuffer corresponding to the view index.

If the view mask is zero for all subpasses, multiview is considered to be disabled and all drawing commands execute normally, without this additional broadcasting.

Some implementations may not support multiview in conjunction with geometry shaders or tessellation shaders.

When multiview is enabled, the VK_DEPENDENCY_VIEW_LOCAL_BIT bit in a dependency can be used to express a view-local dependency, meaning that each view in the destination subpass depends on a single view in the source subpass. Unlike pipeline barriers, a subpass dependency can potentially have a different view mask in the source subpass and the destination subpass. If the dependency is view-local, then each view (dstView) in the destination subpass depends on the view dstView + pViewOffsets[dependency] in the source subpass. If there is not such a view in the source subpass, then this dependency does not affect that view in the destination subpass. If the dependency is not view-local, then all views in the destination subpass depend on all views in the source subpass, and the view offset is ignored. A non-zero view offset is not allowed in a self-dependency.

The elements of pCorrelationMasks are a set of masks of views indicating that views in the same mask may exhibit spatial coherency between the views, making it more efficient to render them concurrently. Correlation masks must not have a functional effect on the results of the multiview rendering.

When multiview is enabled, at the beginning of each subpass all non-render pass state is undefined. In particular, each time vkCmdBeginRenderPass or vkCmdNextSubpass is called the graphics pipeline must be bound, any relevant descriptor sets or vertex/index buffers must be bound, and any relevant dynamic state or push constants must be set before they are used.

A multiview subpass can declare that its shaders will write per-view attributes for all views in a single invocation, by setting the VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX bit in the subpass description. The only supported per-view attributes are position and viewport mask, and per-view position and viewport masks are written to output array variables decorated with PositionPerViewNV and ViewportMaskPerViewNV, respectively. If VK_NV_viewport_array2 is not supported and enabled, ViewportMaskPerViewNV must not be used. Values written to elements of PositionPerViewNV and ViewportMaskPerViewNV must not depend on the ViewIndex. The shader must also write to an output variable decorated with Position, and the value written to Position must equal the value written to PositionPerViewNV[ViewIndex]. Similarly, if ViewportMaskPerViewNV is written to then the shader must also write to an output variable decorated with ViewportMaskNV, and the value written to ViewportMaskNV must equal the value written to ViewportMaskPerViewNV[ViewIndex]. Implementations will either use values taken from Position and ViewportMaskNV and invoke the shader once for each view, or will use values taken from PositionPerViewNV and ViewportMaskPerViewNV and invoke the shader fewer times. The values written to Position and ViewportMaskNV must not depend on the values written to PositionPerViewNV and ViewportMaskPerViewNV, or vice versa (to allow compilers to eliminate the unused outputs). All attributes that do not have *PerViewNV counterparts must not depend on ViewIndex.

Per-view attributes are all-or-nothing for a subpass. That is, all pipelines compiled against a subpass that includes the VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX bit must write per-view attributes to the *PerViewNV[] shader outputs, in addition to the non-per-view (e.g. Position) outputs. Pipelines compiled against a subpass that does not include this bit must not include the *PerViewNV[] outputs in their interfaces.

Valid Usage
  • Each view index must not be set in more than one element of pCorrelationMasks

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_RENDER_PASS_MULTIVIEW_CREATE_INFO

  • If subpassCount is not 0, pViewMasks must be a valid pointer to an array of subpassCount uint32_t values

  • If dependencyCount is not 0, pViewOffsets must be a valid pointer to an array of dependencyCount int32_t values

  • If correlationMaskCount is not 0, pCorrelationMasks must be a valid pointer to an array of correlationMaskCount uint32_t values

The VkAttachmentDescription structure is defined as:

typedef struct VkAttachmentDescription {
    VkAttachmentDescriptionFlags    flags;
    VkFormat                        format;
    VkSampleCountFlagBits           samples;
    VkAttachmentLoadOp              loadOp;
    VkAttachmentStoreOp             storeOp;
    VkAttachmentLoadOp              stencilLoadOp;
    VkAttachmentStoreOp             stencilStoreOp;
    VkImageLayout                   initialLayout;
    VkImageLayout                   finalLayout;
} VkAttachmentDescription;
  • flags is a bitmask of VkAttachmentDescriptionFlagBits specifying additional properties of the attachment.

  • format is a VkFormat value specifying the format of the image view that will be used for the attachment.

  • samples is the number of samples of the image as defined in VkSampleCountFlagBits.

  • loadOp is a VkAttachmentLoadOp value specifying how the contents of color and depth components of the attachment are treated at the beginning of the subpass where it is first used.

  • storeOp is a VkAttachmentStoreOp value specifying how the contents of color and depth components of the attachment are treated at the end of the subpass where it is last used.

  • stencilLoadOp is a VkAttachmentLoadOp value specifying how the contents of stencil components of the attachment are treated at the beginning of the subpass where it is first used.

  • stencilStoreOp is a VkAttachmentStoreOp value specifying how the contents of stencil components of the attachment are treated at the end of the last subpass where it is used.

  • initialLayout is the layout the attachment image subresource will be in when a render pass instance begins.

  • finalLayout is the layout the attachment image subresource will be transitioned to when a render pass instance ends. During a render pass instance, an attachment can use a different layout in each subpass, if desired.

If the attachment uses a color format, then loadOp and storeOp are used, and stencilLoadOp and stencilStoreOp are ignored. If the format has depth and/or stencil components, loadOp and storeOp apply only to the depth data, while stencilLoadOp and stencilStoreOp define how the stencil data is handled. loadOp and stencilLoadOp define the load operations that execute as part of the first subpass that uses the attachment. storeOp and stencilStoreOp define the store operations that execute as part of the last subpass that uses the attachment.

The load operation for each sample in an attachment happens-before any recorded command which accesses the sample in the first subpass where the attachment is used. Load operations for attachments with a depth/stencil format execute in the VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT pipeline stage. Load operations for attachments with a color format execute in the VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT pipeline stage.

The store operation for each sample in an attachment happens-after any recorded command which accesses the sample in the last subpass where the attachment is used. Store operations for attachments with a depth/stencil format execute in the VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT pipeline stage. Store operations for attachments with a color format execute in the VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT pipeline stage.

If an attachment is not used by any subpass, then loadOp, storeOp, stencilStoreOp, and stencilLoadOp are ignored, and the attachment’s memory contents will not be modified by execution of a render pass instance.

The load and store operations apply on the first and last use of each view in the render pass, respectively. If a view index of an attachment is not included in the view mask in any subpass that uses it, then the load and store operations are ignored, and the attachment’s memory contents will not be modified by execution of a render pass instance.

During a render pass instance, input/color attachments with color formats that have a component size of 8, 16, or 32 bits must be represented in the attachment’s format throughout the instance. Attachments with other floating- or fixed-point color formats, or with depth components may be represented in a format with a precision higher than the attachment format, but must be represented with the same range. When such a component is loaded via the loadOp, it will be converted into an implementation-dependent format used by the render pass. Such components must be converted from the render pass format, to the format of the attachment, before they are resolved or stored at the end of a render pass instance via storeOp. Conversions occur as described in Numeric Representation and Computation and Fixed-Point Data Conversions.

If flags includes VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT, then the attachment is treated as if it shares physical memory with another attachment in the same render pass. This information limits the ability of the implementation to reorder certain operations (like layout transitions and the loadOp) such that it is not improperly reordered against other uses of the same physical memory via a different attachment. This is described in more detail below.

Valid Usage
  • finalLayout must not be VK_IMAGE_LAYOUT_UNDEFINED or VK_IMAGE_LAYOUT_PREINITIALIZED

Valid Usage (Implicit)

To specify which aspects of an input attachment can be read add a VkRenderPassInputAttachmentAspectCreateInfo structure to the pNext chain of the VkRenderPassCreateInfo structure:

The VkRenderPassInputAttachmentAspectCreateInfo structure is defined as:

typedef struct VkRenderPassInputAttachmentAspectCreateInfo {
    VkStructureType                            sType;
    const void*                                pNext;
    uint32_t                                   aspectReferenceCount;
    const VkInputAttachmentAspectReference*    pAspectReferences;
} VkRenderPassInputAttachmentAspectCreateInfo;

or the equivalent

typedef VkRenderPassInputAttachmentAspectCreateInfo VkRenderPassInputAttachmentAspectCreateInfoKHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • aspectReferenceCount is the number of elements in the pAspectReferences array.

  • pAspectReferences points to an array of aspectReferenceCount number of VkInputAttachmentAspectReference structures describing which aspect(s) can be accessed for a given input attachment within a given subpass.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_RENDER_PASS_INPUT_ATTACHMENT_ASPECT_CREATE_INFO

  • pAspectReferences must be a valid pointer to an array of aspectReferenceCount valid VkInputAttachmentAspectReference structures

  • aspectReferenceCount must be greater than 0

The VkInputAttachmentAspectReference structure specifies an aspect mask for a specific input attachment of a specific subpass in the render pass.

subpass and inputAttachmentIndex index into the render pass as:

pCreateInfo::pSubpasses[subpass].pInputAttachments[inputAttachmentIndex]

typedef struct VkInputAttachmentAspectReference {
    uint32_t              subpass;
    uint32_t              inputAttachmentIndex;
    VkImageAspectFlags    aspectMask;
} VkInputAttachmentAspectReference;

or the equivalent

typedef VkInputAttachmentAspectReference VkInputAttachmentAspectReferenceKHR;
  • subpass is an index into the pSubpasses array of the parent VkRenderPassCreateInfo structure.

  • inputAttachmentIndex is an index into the pInputAttachments of the specified subpass.

  • aspectMask is a mask of which aspect(s) can be accessed within the specified subpass.

Valid Usage
  • aspectMask must not include VK_IMAGE_ASPECT_METADATA_BIT

Valid Usage (Implicit)

An application must only access the specified aspect(s).

An application can access any aspect of an input attachment that does not have a specified aspect mask.

Bits which can be set in VkAttachmentDescription::flags describing additional properties of the attachment are:

typedef enum VkAttachmentDescriptionFlagBits {
    VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT = 0x00000001,
} VkAttachmentDescriptionFlagBits;
  • VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT specifies that the attachment aliases the same device memory as other attachments.

typedef VkFlags VkAttachmentDescriptionFlags;

VkAttachmentDescriptionFlags is a bitmask type for setting a mask of zero or more VkAttachmentDescriptionFlagBits.

Possible values of VkAttachmentDescription::loadOp and stencilLoadOp, specifying how the contents of the attachment are treated, are:

typedef enum VkAttachmentLoadOp {
    VK_ATTACHMENT_LOAD_OP_LOAD = 0,
    VK_ATTACHMENT_LOAD_OP_CLEAR = 1,
    VK_ATTACHMENT_LOAD_OP_DONT_CARE = 2,
} VkAttachmentLoadOp;
  • VK_ATTACHMENT_LOAD_OP_LOAD specifies that the previous contents of the image within the render area will be preserved. For attachments with a depth/stencil format, this uses the access type VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT. For attachments with a color format, this uses the access type VK_ACCESS_COLOR_ATTACHMENT_READ_BIT.

  • VK_ATTACHMENT_LOAD_OP_CLEAR specifies that the contents within the render area will be cleared to a uniform value, which is specified when a render pass instance is begun. For attachments with a depth/stencil format, this uses the access type VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT.

  • VK_ATTACHMENT_LOAD_OP_DONT_CARE specifies that the previous contents within the area need not be preserved; the contents of the attachment will be undefined inside the render area. For attachments with a depth/stencil format, this uses the access type VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT.

Possible values of VkAttachmentDescription::storeOp and stencilStoreOp, specifying how the contents of the attachment are treated, are:

typedef enum VkAttachmentStoreOp {
    VK_ATTACHMENT_STORE_OP_STORE = 0,
    VK_ATTACHMENT_STORE_OP_DONT_CARE = 1,
} VkAttachmentStoreOp;
  • VK_ATTACHMENT_STORE_OP_STORE specifies the contents generated during the render pass and within the render area are written to memory. For attachments with a depth/stencil format, this uses the access type VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT.

  • VK_ATTACHMENT_STORE_OP_DONT_CARE specifies the contents within the render area are not needed after rendering, and may be discarded; the contents of the attachment will be undefined inside the render area. For attachments with a depth/stencil format, this uses the access type VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT.

If a render pass uses multiple attachments that alias the same device memory, those attachments must each include the VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT bit in their attachment description flags. Attachments aliasing the same memory occurs in multiple ways:

  • Multiple attachments being assigned the same image view as part of framebuffer creation.

  • Attachments using distinct image views that correspond to the same image subresource of an image.

  • Attachments using views of distinct image subresources which are bound to overlapping memory ranges.

Note

Render passes must include subpass dependencies (either directly or via a subpass dependency chain) between any two subpasses that operate on the same attachment or aliasing attachments and those subpass dependencies must include execution and memory dependencies separating uses of the aliases, if at least one of those subpasses writes to one of the aliases. These dependencies must not include the VK_DEPENDENCY_BY_REGION_BIT if the aliases are views of distinct image subresources which overlap in memory.

Multiple attachments that alias the same memory must not be used in a single subpass. A given attachment index must not be used multiple times in a single subpass, with one exception: two subpass attachments can use the same attachment index if at least one use is as an input attachment and neither use is as a resolve or preserve attachment. In other words, the same view can be used simultaneously as an input and color or depth/stencil attachment, but must not be used as multiple color or depth/stencil attachments nor as resolve or preserve attachments. The precise set of valid scenarios is described in more detail below.

If a set of attachments alias each other, then all except the first to be used in the render pass must use an initialLayout of VK_IMAGE_LAYOUT_UNDEFINED, since the earlier uses of the other aliases make their contents undefined. Once an alias has been used and a different alias has been used after it, the first alias must not be used in any later subpasses. However, an application can assign the same image view to multiple aliasing attachment indices, which allows that image view to be used multiple times even if other aliases are used in between.

Note

Once an attachment needs the VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT bit, there should be no additional cost of introducing additional aliases, and using these additional aliases may allow more efficient clearing of the attachments on multiple uses via VK_ATTACHMENT_LOAD_OP_CLEAR.

The VkSubpassDescription structure is defined as:

typedef struct VkSubpassDescription {
    VkSubpassDescriptionFlags       flags;
    VkPipelineBindPoint             pipelineBindPoint;
    uint32_t                        inputAttachmentCount;
    const VkAttachmentReference*    pInputAttachments;
    uint32_t                        colorAttachmentCount;
    const VkAttachmentReference*    pColorAttachments;
    const VkAttachmentReference*    pResolveAttachments;
    const VkAttachmentReference*    pDepthStencilAttachment;
    uint32_t                        preserveAttachmentCount;
    const uint32_t*                 pPreserveAttachments;
} VkSubpassDescription;
  • flags is a bitmask of VkSubpassDescriptionFlagBits specifying usage of the subpass.

  • pipelineBindPoint is a VkPipelineBindPoint value specifying whether this is a compute or graphics subpass. Currently, only graphics subpasses are supported.

  • inputAttachmentCount is the number of input attachments.

  • pInputAttachments is an array of VkAttachmentReference structures (defined below) that lists which of the render pass’s attachments can be read in the fragment shader stage during the subpass, and what layout each attachment will be in during the subpass. Each element of the array corresponds to an input attachment unit number in the shader, i.e. if the shader declares an input variable layout(input_attachment_index=X, set=Y, binding=Z) then it uses the attachment provided in pInputAttachments[X]. Input attachments must also be bound to the pipeline with a descriptor set, with the input attachment descriptor written in the location (set=Y, binding=Z). Fragment shaders can use subpass input variables to access the contents of an input attachment at the fragment’s (x, y, layer) framebuffer coordinates.

  • colorAttachmentCount is the number of color attachments.

  • pColorAttachments is an array of colorAttachmentCount VkAttachmentReference structures that lists which of the render pass’s attachments will be used as color attachments in the subpass, and what layout each attachment will be in during the subpass. Each element of the array corresponds to a fragment shader output location, i.e. if the shader declared an output variable layout(location=X) then it uses the attachment provided in pColorAttachments[X].

  • pResolveAttachments is NULL or an array of colorAttachmentCount VkAttachmentReference structures that lists which of the render pass’s attachments are resolved to at the end of the subpass, and what layout each attachment will be in during the multisample resolve operation. If pResolveAttachments is not NULL, each of its elements corresponds to a color attachment (the element in pColorAttachments at the same index), and a multisample resolve operation is defined for each attachment. At the end of each subpass, multisample resolve operations read the subpass’s color attachments, and resolve the samples for each pixel to the same pixel location in the corresponding resolve attachments, unless the resolve attachment index is VK_ATTACHMENT_UNUSED. If the first use of an attachment in a render pass is as a resolve attachment, then the loadOp is effectively ignored as the resolve is guaranteed to overwrite all pixels in the render area.

  • pDepthStencilAttachment is a pointer to a VkAttachmentReference specifying which attachment will be used for depth/stencil data and the layout it will be in during the subpass. Setting the attachment index to VK_ATTACHMENT_UNUSED or leaving this pointer as NULL indicates that no depth/stencil attachment will be used in the subpass.

  • preserveAttachmentCount is the number of preserved attachments.

  • pPreserveAttachments is an array of preserveAttachmentCount render pass attachment indices describing the attachments that are not used by a subpass, but whose contents must be preserved throughout the subpass.

The contents of an attachment within the render area become undefined at the start of a subpass S if all of the following conditions are true:

  • The attachment is used as a color, depth/stencil, or resolve attachment in any subpass in the render pass.

  • There is a subpass S1 that uses or preserves the attachment, and a subpass dependency from S1 to S.

  • The attachment is not used or preserved in subpass S.

Once the contents of an attachment become undefined in subpass S, they remain undefined for subpasses in subpass dependency chains starting with subpass S until they are written again. However, they remain valid for subpasses in other subpass dependency chains starting with subpass S1 if those subpasses use or preserve the attachment.

Valid Usage
  • pipelineBindPoint must be VK_PIPELINE_BIND_POINT_GRAPHICS

  • colorAttachmentCount must be less than or equal to VkPhysicalDeviceLimits::maxColorAttachments

  • If the first use of an attachment in this render pass is as an input attachment, and the attachment is not also used as a color or depth/stencil attachment in the same subpass, then loadOp must not be VK_ATTACHMENT_LOAD_OP_CLEAR

  • If pResolveAttachments is not NULL, for each resolve attachment that does not have the value VK_ATTACHMENT_UNUSED, the corresponding color attachment must not have the value VK_ATTACHMENT_UNUSED

  • If pResolveAttachments is not NULL, the sample count of each element of pColorAttachments must be anything other than VK_SAMPLE_COUNT_1_BIT

  • Each element of pResolveAttachments must have a sample count of VK_SAMPLE_COUNT_1_BIT

  • Each element of pResolveAttachments must have the same VkFormat as its corresponding color attachment

  • All attachments in pColorAttachments that are not VK_ATTACHMENT_UNUSED must have the same sample count

  • All attachments in pColorAttachments that are not VK_ATTACHMENT_UNUSED must have a sample count that is smaller than or equal to the sample count of pDepthStencilAttachment if it is not VK_ATTACHMENT_UNUSED

  • If any input attachments are VK_ATTACHMENT_UNUSED, then any pipelines bound during the subpass must not access those input attachments from the fragment shader

  • The attachment member of each element of pPreserveAttachments must not be VK_ATTACHMENT_UNUSED

  • Each element of pPreserveAttachments must not also be an element of any other member of the subpass description

  • If any attachment is used as both an input attachment and a color or depth/stencil attachment, then each use must use the same layout

  • If flags includes VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX, it must also include VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX.

Valid Usage (Implicit)
  • flags must be a valid combination of VkSubpassDescriptionFlagBits values

  • pipelineBindPoint must be a valid VkPipelineBindPoint value

  • If inputAttachmentCount is not 0, pInputAttachments must be a valid pointer to an array of inputAttachmentCount valid VkAttachmentReference structures

  • If colorAttachmentCount is not 0, pColorAttachments must be a valid pointer to an array of colorAttachmentCount valid VkAttachmentReference structures

  • If colorAttachmentCount is not 0, and pResolveAttachments is not NULL, pResolveAttachments must be a valid pointer to an array of colorAttachmentCount valid VkAttachmentReference structures

  • If pDepthStencilAttachment is not NULL, pDepthStencilAttachment must be a valid pointer to a valid VkAttachmentReference structure

  • If preserveAttachmentCount is not 0, pPreserveAttachments must be a valid pointer to an array of preserveAttachmentCount uint32_t values

Bits which can be set in VkSubpassDescription::flags, specifying usage of the subpass, are:

typedef enum VkSubpassDescriptionFlagBits {
    VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX = 0x00000001,
    VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX = 0x00000002,
} VkSubpassDescriptionFlagBits;
  • VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX specifies that shaders compiled for this subpass write the attributes for all views in a single invocation of each vertex processing stage. All pipelines compiled against a subpass that includes this bit must write per-view attributes to the *PerViewNV[] shader outputs, in addition to the non-per-view (e.g. Position) outputs.

  • VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX specifies that shaders compiled for this subpass use per-view positions which only differ in value in the x component. Per-view viewport mask can also be used.

typedef VkFlags VkSubpassDescriptionFlags;

VkSubpassDescriptionFlags is a bitmask type for setting a mask of zero or more VkSubpassDescriptionFlagBits.

The VkAttachmentReference structure is defined as:

typedef struct VkAttachmentReference {
    uint32_t         attachment;
    VkImageLayout    layout;
} VkAttachmentReference;
  • attachment is the index of the attachment of the render pass, and corresponds to the index of the corresponding element in the pAttachments array of the VkRenderPassCreateInfo structure. If any color or depth/stencil attachments are VK_ATTACHMENT_UNUSED, then no writes occur for those attachments.

  • layout is a VkImageLayout value specifying the layout the attachment uses during the subpass.

Valid Usage
  • layout must not be VK_IMAGE_LAYOUT_UNDEFINED or VK_IMAGE_LAYOUT_PREINITIALIZED

Valid Usage (Implicit)

The VkSubpassDependency structure is defined as:

typedef struct VkSubpassDependency {
    uint32_t                srcSubpass;
    uint32_t                dstSubpass;
    VkPipelineStageFlags    srcStageMask;
    VkPipelineStageFlags    dstStageMask;
    VkAccessFlags           srcAccessMask;
    VkAccessFlags           dstAccessMask;
    VkDependencyFlags       dependencyFlags;
} VkSubpassDependency;

If srcSubpass is equal to dstSubpass then the VkSubpassDependency describes a subpass self-dependency, and only constrains the pipeline barriers allowed within a subpass instance. Otherwise, when a render pass instance which includes a subpass dependency is submitted to a queue, it defines a memory dependency between the subpasses identified by srcSubpass and dstSubpass.

If srcSubpass is equal to VK_SUBPASS_EXTERNAL, the first synchronization scope includes commands that occur earlier in submission order than the vkCmdBeginRenderPass used to begin the render pass instance. Otherwise, the first set of commands includes all commands submitted as part of the subpass instance identified by srcSubpass and any load, store or multisample resolve operations on attachments used in srcSubpass. In either case, the first synchronization scope is limited to operations on the pipeline stages determined by the source stage mask specified by srcStageMask.

If dstSubpass is equal to VK_SUBPASS_EXTERNAL, the second synchronization scope includes commands that occur later in submission order than the vkCmdEndRenderPass used to end the render pass instance. Otherwise, the second set of commands includes all commands submitted as part of the subpass instance identified by dstSubpass and any load, store or multisample resolve operations on attachments used in dstSubpass. In either case, the second synchronization scope is limited to operations on the pipeline stages determined by the destination stage mask specified by dstStageMask.

The first access scope is limited to access in the pipeline stages determined by the source stage mask specified by srcStageMask. It is also limited to access types in the source access mask specified by srcAccessMask.

The second access scope is limited to access in the pipeline stages determined by the destination stage mask specified by dstStageMask. It is also limited to access types in the destination access mask specified by dstAccessMask.

The availability and visibility operations defined by a subpass dependency affect the execution of image layout transitions within the render pass.

Note

For non-attachment resources, the memory dependency expressed by subpass dependency is nearly identical to that of a VkMemoryBarrier (with matching srcAccessMask/dstAccessMask parameters) submitted as a part of a vkCmdPipelineBarrier (with matching srcStageMask/dstStageMask parameters). The only difference being that its scopes are limited to the identified subpasses rather than potentially affecting everything before and after.

For attachments however, subpass dependencies work more like a VkImageMemoryBarrier defined similarly to the VkMemoryBarrier above, the queue family indices set to VK_QUEUE_FAMILY_IGNORED, and layouts as follows:

  • The equivalent to oldLayout is the attachment’s layout according to the subpass description for srcSubpass.

  • The equivalent to newLayout is the attachment’s layout according to the subpass description for dstSubpass.

Valid Usage
  • If srcSubpass is not VK_SUBPASS_EXTERNAL, srcStageMask must not include VK_PIPELINE_STAGE_HOST_BIT

  • If dstSubpass is not VK_SUBPASS_EXTERNAL, dstStageMask must not include VK_PIPELINE_STAGE_HOST_BIT

  • If the geometry shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT

  • If the geometry shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT

  • If the tessellation shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT

  • If the tessellation shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT

  • srcSubpass must be less than or equal to dstSubpass, unless one of them is VK_SUBPASS_EXTERNAL, to avoid cyclic dependencies and ensure a valid execution order

  • srcSubpass and dstSubpass must not both be equal to VK_SUBPASS_EXTERNAL

  • If srcSubpass is equal to dstSubpass, srcStageMask and dstStageMask must not set any bits that are neither VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT, nor one of the graphics pipeline stages

  • If srcSubpass is equal to dstSubpass and not all of the stages in srcStageMask and dstStageMask are framebuffer-space stages, the logically latest pipeline stage in srcStageMask must be logically earlier than or equal to the logically earliest pipeline stage in dstStageMask

  • Any access flag included in srcAccessMask must be supported by one of the pipeline stages in srcStageMask, as specified in the table of supported access types

  • Any access flag included in dstAccessMask must be supported by one of the pipeline stages in dstStageMask, as specified in the table of supported access types

  • If srcSubpass equals dstSubpass, and srcStageMask and dstStageMask both include a framebuffer-space stage, then dependencyFlags must include VK_DEPENDENCY_BY_REGION_BIT

  • If dependencyFlags includes VK_DEPENDENCY_VIEW_LOCAL_BIT, then both srcSubpass and dstSubpass must not equal VK_SUBPASS_EXTERNAL

  • If dependencyFlags includes VK_DEPENDENCY_VIEW_LOCAL_BIT, then the render pass must have multiview enabled

  • If srcSubpass equals dstSubpass and that subpass has more than one bit set in the view mask, then dependencyFlags must include VK_DEPENDENCY_VIEW_LOCAL_BIT

  • If the mesh shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_MESH_SHADER_BIT_NV

  • If the task shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_TASK_SHADER_BIT_NV

  • If the mesh shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_MESH_SHADER_BIT_NV

  • If the task shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_TASK_SHADER_BIT_NV

Valid Usage (Implicit)

When multiview is enabled, the execution of the multiple views of one subpass may not occur simultaneously or even back-to-back, and rather may be interleaved with the execution of other subpasses. The load and store operations apply to attachments on a per-view basis. For example, an attachment using VK_ATTACHMENT_LOAD_OP_CLEAR will have each view cleared on first use, but the first use of one view may be temporally distant from the first use of another view.

Note

A good mental model for multiview is to think of a multiview subpass as if it were a collection of individual (per-view) subpasses that are logically grouped together and described as a single multiview subpass in the API. Similarly, a multiview attachment can be thought of like several individual attachments that happen to be layers in a single image. A view-local dependency between two multiview subpasses acts like a set of one-to-one dependencies between corresponding pairs of per-view subpasses. A view-global dependency between two multiview subpasses acts like a set of N × M dependencies between all pairs of per-view subpasses in the source and destination. Thus, it is a more compact representation which also makes clear the commonality and reuse that is present between views in a subpass. This interpretation motivates the answers to questions like “when does the load op apply” - it is on the first use of each view of an attachment, as if each view were a separate attachment.

If there is no subpass dependency from VK_SUBPASS_EXTERNAL to the first subpass that uses an attachment, then an implicit subpass dependency exists from VK_SUBPASS_EXTERNAL to the first subpass it is used in. The subpass dependency operates as if defined with the following parameters:

VkSubpassDependency implicitDependency = {
    .srcSubpass = VK_SUBPASS_EXTERNAL;
    .dstSubpass = firstSubpass; // First subpass attachment is used in
    .srcStageMask = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
    .dstStageMask = VK_PIPELINE_STAGE_ALL_COMMANDS_BIT;
    .srcAccessMask = 0;
    .dstAccessMask = VK_ACCESS_INPUT_ATTACHMENT_READ_BIT |
                     VK_ACCESS_COLOR_ATTACHMENT_READ_BIT |
                     VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT |
                     VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT |
                     VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
    .dependencyFlags = 0;
};

Similarly, if there is no subpass dependency from the last subpass that uses an attachment to VK_SUBPASS_EXTERNAL, then an implicit subpass dependency exists from the last subpass it is used in to VK_SUBPASS_EXTERNAL. The subpass dependency operates as if defined with the following parameters:

VkSubpassDependency implicitDependency = {
    .srcSubpass = lastSubpass; // Last subpass attachment is used in
    .dstSubpass = VK_SUBPASS_EXTERNAL;
    .srcStageMask = VK_PIPELINE_STAGE_ALL_COMMANDS_BIT;
    .dstStageMask = VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT;
    .srcAccessMask = VK_ACCESS_INPUT_ATTACHMENT_READ_BIT |
                     VK_ACCESS_COLOR_ATTACHMENT_READ_BIT |
                     VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT |
                     VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT |
                     VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
    .dstAccessMask = 0;
    .dependencyFlags = 0;
};

As subpasses may overlap or execute out of order with regards to other subpasses unless a subpass dependency chain describes otherwise, the layout transitions required between subpasses cannot be known to an application. Instead, an application provides the layout that each attachment must be in at the start and end of a render pass, and the layout it must be in during each subpass it is used in. The implementation then must execute layout transitions between subpasses in order to guarantee that the images are in the layouts required by each subpass, and in the final layout at the end of the render pass.

Automatic layout transitions apply to the entire image subresource attached to the framebuffer. If the attachment view is a 2D or 2D array view of a 3D image, even if the attachment view only refers to a subset of the slices of the selected mip level of the 3D image, automatic layout transitions apply to the entire subresource referenced which is the entire mip level in this case.

Automatic layout transitions away from the layout used in a subpass happen-after the availability operations for all dependencies with that subpass as the srcSubpass.

Automatic layout transitions into the layout used in a subpass happen-before the visibility operations for all dependencies with that subpass as the dstSubpass.

Automatic layout transitions away from initialLayout happens-after the availability operations for all dependencies with a srcSubpass equal to VK_SUBPASS_EXTERNAL, where dstSubpass uses the attachment that will be transitioned. For attachments created with VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT, automatic layout transitions away from initialLayout happen-after the availability operations for all dependencies with a srcSubpass equal to VK_SUBPASS_EXTERNAL, where dstSubpass uses any aliased attachment.

Automatic layout transitions into finalLayout happens-before the visibility operations for all dependencies with a dstSubpass equal to VK_SUBPASS_EXTERNAL, where srcSubpass uses the attachment that will be transitioned. For attachments created with VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT, automatic layout transitions into finalLayout happen-before the visibility operations for all dependencies with a dstSubpass equal to VK_SUBPASS_EXTERNAL, where srcSubpass uses any aliased attachment.

The image layout of the depth aspect of a depth/stencil attachment referring to an image created with VK_IMAGE_CREATE_SAMPLE_LOCATIONS_COMPATIBLE_DEPTH_BIT_EXT is dependent on the last sample locations used to render to the attachment, thus automatic layout transitions use the sample locations state specified in VkRenderPassSampleLocationsBeginInfoEXT.

Automatic layout transitions of an attachment referring to a depth/stencil image created with VK_IMAGE_CREATE_SAMPLE_LOCATIONS_COMPATIBLE_DEPTH_BIT_EXT use the sample locations the image subresource range referenced by the attachment was last rendered with. If the current render pass does not use the attachment as a depth/stencil attachment in any subpass that happens-before, the automatic layout transition uses the sample locations state specified in the sampleLocationsInfo member of the element of the VkRenderPassSampleLocationsBeginInfoEXT::pAttachmentInitialSampleLocations array for which the attachmentIndex member equals the attachment index of the attachment, if one is specified. Otherwise, the automatic layout transition uses the sample locations state specified in the sampleLocationsInfo member of the element of the VkRenderPassSampleLocationsBeginInfoEXT::pPostSubpassSampleLocations array for which the subpassIndex member equals the index of the subpass that last used the attachment as a depth/stencil attachment, if one is specified.

If no sample locations state has been specified for an automatic layout transition performed on an attachment referring to a depth/stencil image created with VK_IMAGE_CREATE_SAMPLE_LOCATIONS_COMPATIBLE_DEPTH_BIT_EXT the contents of the depth aspect of the depth/stencil attachment become undefined as if the layout of the attachment was transitioned from the VK_IMAGE_LAYOUT_UNDEFINED layout.

If two subpasses use the same attachment in different layouts, and both layouts are read-only, no subpass dependency needs to be specified between those subpasses. If an implementation treats those layouts separately, it must insert an implicit subpass dependency between those subpasses to separate the uses in each layout. The subpass dependency operates as if defined with the following parameters:

// Used for input attachments
VkPipelineStageFlags inputAttachmentStages = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
VkAccessFlags inputAttachmentAccess = VK_ACCESS_INPUT_ATTACHMENT_READ_BIT;

// Used for depth/stencil attachments
VkPipelineStageFlags depthStencilAttachmentStages = VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT | VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT;
VkAccessFlags depthStencilAttachmentAccess = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT;

VkSubpassDependency implicitDependency = {
    .srcSubpass = firstSubpass;
    .dstSubpass = secondSubpass;
    .srcStageMask = inputAttachmentStages | depthStencilAttachmentStages;
    .dstStageMask = inputAttachmentStages | depthStencilAttachmentStages;
    .srcAccessMask = inputAttachmentAccess | depthStencilAttachmentAccess;
    .dstAccessMask = inputAttachmentAccess | depthStencilAttachmentAccess;
    .dependencyFlags = 0;
};

If a subpass uses the same attachment as both an input attachment and either a color attachment or a depth/stencil attachment, writes via the color or depth/stencil attachment are not automatically made visible to reads via the input attachment, causing a feedback loop, except in any of the following conditions:

  • If the color components or depth/stencil components read by the input attachment are mutually exclusive with the components written by the color or depth/stencil attachments, then there is no feedback loop. This requires the graphics pipelines used by the subpass to disable writes to color components that are read as inputs via the colorWriteMask, and to disable writes to depth/stencil components that are read as inputs via depthWriteEnable or stencilTestEnable.

  • If the attachment is used as an input attachment and depth/stencil attachment only, and the depth/stencil attachment is not written to.

  • If a memory dependency is inserted between when the attachment is written and when it is subsequently read by later fragments. Pipeline barriers expressing a subpass self-dependency are the only way to achieve this, and one must be inserted every time a fragment will read values at a particular sample (x, y, layer, sample) coordinate, if those values have been written since the most recent pipeline barrier; or the since start of the subpass if there have been no pipeline barriers since the start of the subpass.

An attachment used as both an input attachment and a color attachment must be in the VK_IMAGE_LAYOUT_SHARED_PRESENT_KHR or VK_IMAGE_LAYOUT_GENERAL layout. An attachment used as an input attachment and depth/stencil attachment must be in the VK_IMAGE_LAYOUT_SHARED_PRESENT_KHR, VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL, or VK_IMAGE_LAYOUT_GENERAL layout. An attachment must not be used as both a depth/stencil attachment and a color attachment.

A more extensible version of render pass creation is also defined below.

To create a render pass, call:

VkResult vkCreateRenderPass2KHR(
    VkDevice                                    device,
    const VkRenderPassCreateInfo2KHR*           pCreateInfo,
    const VkAllocationCallbacks*                pAllocator,
    VkRenderPass*                               pRenderPass);
  • device is the logical device that creates the render pass.

  • pCreateInfo is a pointer to an instance of the VkRenderPassCreateInfo2KHR structure that describes the parameters of the render pass.

  • pAllocator controls host memory allocation as described in the Memory Allocation chapter.

  • pRenderPass points to a VkRenderPass handle in which the resulting render pass object is returned.

This command is functionally identical to vkCreateRenderPass, but includes extensible sub-structures that include sType and pNext parameters, allowing them to be more easily extended.

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • pCreateInfo must be a valid pointer to a valid VkRenderPassCreateInfo2KHR structure

  • If pAllocator is not NULL, pAllocator must be a valid pointer to a valid VkAllocationCallbacks structure

  • pRenderPass must be a valid pointer to a VkRenderPass handle

Return Codes
Success
  • VK_SUCCESS

Failure
  • VK_ERROR_OUT_OF_HOST_MEMORY

  • VK_ERROR_OUT_OF_DEVICE_MEMORY

The VkRenderPassCreateInfo2KHR structure is defined as:

typedef struct VkRenderPassCreateInfo2KHR {
    VkStructureType                       sType;
    const void*                           pNext;
    VkRenderPassCreateFlags               flags;
    uint32_t                              attachmentCount;
    const VkAttachmentDescription2KHR*    pAttachments;
    uint32_t                              subpassCount;
    const VkSubpassDescription2KHR*       pSubpasses;
    uint32_t                              dependencyCount;
    const VkSubpassDependency2KHR*        pDependencies;
    uint32_t                              correlatedViewMaskCount;
    const uint32_t*                       pCorrelatedViewMasks;
} VkRenderPassCreateInfo2KHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • flags is reserved for future use.

  • attachmentCount is the number of attachments used by this render pass.

  • pAttachments points to an array of attachmentCount VkAttachmentDescription2KHR structures describing the attachments used by the render pass.

  • subpassCount is the number of subpasses to create.

  • pSubpasses points to an array of subpassCount VkSubpassDescription2KHR structures describing each subpass.

  • dependencyCount is the number of dependencies between pairs of subpasses.

  • pDependencies points to an array of dependencyCount VkSubpassDependency2KHR structures describing dependencies between pairs of subpasses.

  • correlatedViewMaskCount is the number of correlation masks.

  • pCorrelatedViewMasks is an array of view masks indicating sets of views that may be more efficient to render concurrently.

Parameters defined by this structure with the same name as those in VkRenderPassCreateInfo have the identical effect to those parameters; the child structures are variants of those used in VkRenderPassCreateInfo which include sType and pNext parameters, allowing them to be extended.

If the VkSubpassDescription2KHR::viewMask member of any element of pSubpasses is not zero, multiview functionality is considered to be enabled for this render pass.

correlatedViewMaskCount and pCorrelatedViewMasks have the same effect as VkRenderPassMultiviewCreateInfo::correlationMaskCount and VkRenderPassMultiviewCreateInfo::pCorrelationMasks, respectively.

Valid Usage
  • If any two subpasses operate on attachments with overlapping ranges of the same VkDeviceMemory object, and at least one subpass writes to that area of VkDeviceMemory, a subpass dependency must be included (either directly or via some intermediate subpasses) between them

  • If the attachment member of any element of pInputAttachments, pColorAttachments, pResolveAttachments or pDepthStencilAttachment, or the attachment indexed by any element of pPreserveAttachments in any given element of pSubpasses is bound to a range of a VkDeviceMemory object that overlaps with any other attachment in any subpass (including the same subpass), the VkAttachmentDescription2KHR structures describing them must include VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT in flags

  • If the attachment member of any element of pInputAttachments, pColorAttachments, pResolveAttachments or pDepthStencilAttachment, or any element of pPreserveAttachments in any given element of pSubpasses is not VK_ATTACHMENT_UNUSED, it must be less than attachmentCount

  • The value of any element of the pPreserveAttachments member in any given element of pSubpasses must not be VK_ATTACHMENT_UNUSED

  • For any member of pAttachments with a loadOp equal to VK_ATTACHMENT_LOAD_OP_CLEAR, the first use of that attachment must not specify a layout equal to VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL or VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL.

  • For any element of pDependencies, if the srcSubpass is not VK_SUBPASS_EXTERNAL, all stage flags included in the srcStageMask member of that dependency must be a pipeline stage supported by the pipeline identified by the pipelineBindPoint member of the source subpass.

  • For any element of pDependencies, if the dstSubpass is not VK_SUBPASS_EXTERNAL, all stage flags included in the dstStageMask member of that dependency must be a pipeline stage supported by the pipeline identified by the pipelineBindPoint member of the source subpass.

  • The set of bits included in any element of pCorrelatedViewMasks must not overlap with the set of bits included in any other element of pCorrelatedViewMasks

  • If the VkSubpassDescription2KHR::viewMask member of all elements of pSubpasses is 0, correlatedViewMaskCount must be 0

  • The VkSubpassDescription2KHR::viewMask member of all elements of pSubpasses must either all be 0, or all not be 0

  • If the VkSubpassDescription2KHR::viewMask member of all elements of pSubpasses is 0, the dependencyFlags member of any element of pDependencies must not include VK_DEPENDENCY_VIEW_LOCAL_BIT

  • For any element of pDependencies where its srcSubpass member equals its dstSubpass member, if the viewMask member of the corresponding element of pSubpasses includes more than one bit, its dependencyFlags member must include VK_DEPENDENCY_VIEW_LOCAL_BIT

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO_2_KHR

  • pNext must be NULL

  • flags must be 0

  • If attachmentCount is not 0, pAttachments must be a valid pointer to an array of attachmentCount valid VkAttachmentDescription2KHR structures

  • pSubpasses must be a valid pointer to an array of subpassCount valid VkSubpassDescription2KHR structures

  • If dependencyCount is not 0, pDependencies must be a valid pointer to an array of dependencyCount valid VkSubpassDependency2KHR structures

  • If correlatedViewMaskCount is not 0, pCorrelatedViewMasks must be a valid pointer to an array of correlatedViewMaskCount uint32_t values

  • subpassCount must be greater than 0

The VkAttachmentDescription2KHR structure is defined as:

typedef struct VkAttachmentDescription2KHR {
    VkStructureType                 sType;
    const void*                     pNext;
    VkAttachmentDescriptionFlags    flags;
    VkFormat                        format;
    VkSampleCountFlagBits           samples;
    VkAttachmentLoadOp              loadOp;
    VkAttachmentStoreOp             storeOp;
    VkAttachmentLoadOp              stencilLoadOp;
    VkAttachmentStoreOp             stencilStoreOp;
    VkImageLayout                   initialLayout;
    VkImageLayout                   finalLayout;
} VkAttachmentDescription2KHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • flags is a bitmask of VkAttachmentDescription2KHRFlagBits specifying additional properties of the attachment.

  • format is a VkFormat value specifying the format of the image that will be used for the attachment.

  • samples is the number of samples of the image as defined in VkSampleCountFlagBits.

  • loadOp is a VkAttachmentLoadOp value specifying how the contents of color and depth components of the attachment are treated at the beginning of the subpass where it is first used.

  • storeOp is a VkAttachmentStoreOp value specifying how the contents of color and depth components of the attachment are treated at the end of the subpass where it is last used.

  • stencilLoadOp is a VkAttachmentLoadOp value specifying how the contents of stencil components of the attachment are treated at the beginning of the subpass where it is first used.

  • stencilStoreOp is a VkAttachmentStoreOp value specifying how the contents of stencil components of the attachment are treated at the end of the last subpass where it is used.

  • initialLayout is the layout the attachment image subresource will be in when a render pass instance begins.

  • finalLayout is the layout the attachment image subresource will be transitioned to when a render pass instance ends.

Parameters defined by this structure with the same name as those in VkAttachmentDescription have the identical effect to those parameters.

Valid Usage
  • finalLayout must not be VK_IMAGE_LAYOUT_UNDEFINED or VK_IMAGE_LAYOUT_PREINITIALIZED

Valid Usage (Implicit)

The VkSubpassDescription2KHR structure is defined as:

typedef struct VkSubpassDescription2KHR {
    VkStructureType                     sType;
    const void*                         pNext;
    VkSubpassDescriptionFlags           flags;
    VkPipelineBindPoint                 pipelineBindPoint;
    uint32_t                            viewMask;
    uint32_t                            inputAttachmentCount;
    const VkAttachmentReference2KHR*    pInputAttachments;
    uint32_t                            colorAttachmentCount;
    const VkAttachmentReference2KHR*    pColorAttachments;
    const VkAttachmentReference2KHR*    pResolveAttachments;
    const VkAttachmentReference2KHR*    pDepthStencilAttachment;
    uint32_t                            preserveAttachmentCount;
    const uint32_t*                     pPreserveAttachments;
} VkSubpassDescription2KHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • flags is a bitmask of VkSubpassDescriptionFlagBits specifying usage of the subpass.

  • pipelineBindPoint is a VkPipelineBindPoint value specifying the pipeline type supported for this subpass.

  • viewMask is a bitfield of view indices describing which views rendering is broadcast to in this subpass, when multiview is enabled.

  • inputAttachmentCount is the number of input attachments.

  • pInputAttachments is an array of VkAttachmentReference structures defining the input attachments for this subpass and their layouts.

  • colorAttachmentCount is the number of color attachments.

  • pColorAttachments is an array of VkAttachmentReference structures defining the color attachments for this subpass and their layouts.

  • pResolveAttachments is an optional array of colorAttachmentCount VkAttachmentReference structures defining the resolve attachments for this subpass and their layouts.

  • pDepthStencilAttachment is a pointer to a VkAttachmentReference specifying the depth/stencil attachment for this subpass and its layout.

  • preserveAttachmentCount is the number of preserved attachments.

  • pPreserveAttachments is an array of preserveAttachmentCount render pass attachment indices identifying attachments that are not used by this subpass, but whose contents must be preserved throughout the subpass.

Parameters defined by this structure with the same name as those in VkSubpassDescription have the identical effect to those parameters.

viewMask has the same effect for the described subpass as VkRenderPassMultiviewCreateInfo::pViewMasks has on each corresponding subpass.

Valid Usage
  • pipelineBindPoint must be VK_PIPELINE_BIND_POINT_GRAPHICS

  • colorAttachmentCount must be less than or equal to VkPhysicalDeviceLimits::maxColorAttachments

  • If the first use of an attachment in this render pass is as an input attachment, and the attachment is not also used as a color or depth/stencil attachment in the same subpass, then loadOp must not be VK_ATTACHMENT_LOAD_OP_CLEAR

  • If pResolveAttachments is not NULL, for each resolve attachment that does not have the value VK_ATTACHMENT_UNUSED, the corresponding color attachment must not have the value VK_ATTACHMENT_UNUSED

  • If pResolveAttachments is not NULL, the sample count of each element of pColorAttachments must be anything other than VK_SAMPLE_COUNT_1_BIT

  • Any given element of pResolveAttachments must have a sample count of VK_SAMPLE_COUNT_1_BIT

  • Any given element of pResolveAttachments must have the same VkFormat as its corresponding color attachment

  • All attachments in pColorAttachments that are not VK_ATTACHMENT_UNUSED must have the same sample count

  • All attachments in pColorAttachments that are not VK_ATTACHMENT_UNUSED must have a sample count that is smaller than or equal to the sample count of pDepthStencilAttachment if it is not VK_ATTACHMENT_UNUSED

  • If any input attachments are VK_ATTACHMENT_UNUSED, then any pipelines bound during the subpass must not access those input attachments from the fragment shader

  • The attachment member of any element of pPreserveAttachments must not be VK_ATTACHMENT_UNUSED

  • Any given element of pPreserveAttachments must not also be an element of any other member of the subpass description

  • If any attachment is used as both an input attachment and a color or depth/stencil attachment, then each use must use the same layout

  • If flags includes VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX, it must also include VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX.

  • The aspectMask member of any element of pInputAttachments must be a valid combination of VkImageAspectFlagBits

  • The aspectMask member of any element of pInputAttachments must not be 0

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_SUBPASS_DESCRIPTION_2_KHR

  • flags must be a valid combination of VkSubpassDescriptionFlagBits values

  • pipelineBindPoint must be a valid VkPipelineBindPoint value

  • If inputAttachmentCount is not 0, pInputAttachments must be a valid pointer to an array of inputAttachmentCount valid VkAttachmentReference2KHR structures

  • If colorAttachmentCount is not 0, pColorAttachments must be a valid pointer to an array of colorAttachmentCount valid VkAttachmentReference2KHR structures

  • If colorAttachmentCount is not 0, and pResolveAttachments is not NULL, pResolveAttachments must be a valid pointer to an array of colorAttachmentCount valid VkAttachmentReference2KHR structures

  • If pDepthStencilAttachment is not NULL, pDepthStencilAttachment must be a valid pointer to a valid VkAttachmentReference2KHR structure

  • If preserveAttachmentCount is not 0, pPreserveAttachments must be a valid pointer to an array of preserveAttachmentCount uint32_t values

The VkAttachmentReference2KHR structure is defined as:

typedef struct VkAttachmentReference2KHR {
    VkStructureType       sType;
    const void*           pNext;
    uint32_t              attachment;
    VkImageLayout         layout;
    VkImageAspectFlags    aspectMask;
} VkAttachmentReference2KHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • attachment is either an integer value identifying an attachment at the corresponding index in VkRenderPassCreateInfo::pAttachments, or VK_ATTACHMENT_UNUSED to signify that this attachment is not used.

  • layout is a VkImageLayout value specifying the layout the attachment uses during the subpass.

  • aspectMask is a mask of which aspect(s) can be accessed within the specified subpass as an input attachment.

Parameters defined by this structure with the same name as those in VkAttachmentReference have the identical effect to those parameters.

aspectMask has the same effect for the described attachment as VkInputAttachmentAspectReference::aspectMask has on each corresponding attachment. It is ignored when this structure is used to describe anything other than an input attachment reference.

Valid Usage
  • layout must not be VK_IMAGE_LAYOUT_UNDEFINED or VK_IMAGE_LAYOUT_PREINITIALIZED

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2_KHR

  • layout must be a valid VkImageLayout value

The VkSubpassDependency2KHR structure is defined as:

typedef struct VkSubpassDependency2KHR {
    VkStructureType         sType;
    const void*             pNext;
    uint32_t                srcSubpass;
    uint32_t                dstSubpass;
    VkPipelineStageFlags    srcStageMask;
    VkPipelineStageFlags    dstStageMask;
    VkAccessFlags           srcAccessMask;
    VkAccessFlags           dstAccessMask;
    VkDependencyFlags       dependencyFlags;
    int32_t                 viewOffset;
} VkSubpassDependency2KHR;

Parameters defined by this structure with the same name as those in VkSubpassDependency have the identical effect to those parameters.

viewOffset has the same effect for the described subpass dependency as VkRenderPassMultiviewCreateInfo::pViewOffsets has on each corresponding subpass dependency.

Valid Usage
  • If srcSubpass is not VK_SUBPASS_EXTERNAL, srcStageMask must not include VK_PIPELINE_STAGE_HOST_BIT

  • If dstSubpass is not VK_SUBPASS_EXTERNAL, dstStageMask must not include VK_PIPELINE_STAGE_HOST_BIT

  • If the geometry shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT

  • If the geometry shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT

  • If the tessellation shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT

  • If the tessellation shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT

  • srcSubpass must be less than or equal to dstSubpass, unless one of them is VK_SUBPASS_EXTERNAL, to avoid cyclic dependencies and ensure a valid execution order

  • srcSubpass and dstSubpass must not both be equal to VK_SUBPASS_EXTERNAL

  • If srcSubpass is equal to dstSubpass, srcStageMask and dstStageMask must not set any bits that are neither VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT, nor one of the graphics pipeline stages

  • If srcSubpass is equal to dstSubpass and not all of the stages in srcStageMask and dstStageMask are framebuffer-space stages, the logically latest pipeline stage in srcStageMask must be logically earlier than or equal to the logically earliest pipeline stage in dstStageMask

  • Any access flag included in srcAccessMask must be supported by one of the pipeline stages in srcStageMask, as specified in the table of supported access types

  • Any access flag included in dstAccessMask must be supported by one of the pipeline stages in dstStageMask, as specified in the table of supported access types

  • If dependencyFlags includes VK_DEPENDENCY_VIEW_LOCAL_BIT, srcSubpass must not be equal to VK_SUBPASS_EXTERNAL

  • If dependencyFlags includes VK_DEPENDENCY_VIEW_LOCAL_BIT, dstSubpass must not be equal to VK_SUBPASS_EXTERNAL

  • If srcSubpass equals dstSubpass, and srcStageMask and dstStageMask both include a framebuffer-space stage, then dependencyFlags must include VK_DEPENDENCY_BY_REGION_BIT

  • If dependencyFlags does not include VK_DEPENDENCY_VIEW_LOCAL_BIT, viewOffset must be 0

  • If viewOffset is not 0, srcSubpass must not be equal to dstSubpass.

  • If the mesh shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_MESH_SHADER_BIT_NV

  • If the task shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_TASK_SHADER_BIT_NV

  • If the mesh shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_MESH_SHADER_BIT_NV

  • If the task shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_TASK_SHADER_BIT_NV

Valid Usage (Implicit)

To destroy a render pass, call:

void vkDestroyRenderPass(
    VkDevice                                    device,
    VkRenderPass                                renderPass,
    const VkAllocationCallbacks*                pAllocator);
  • device is the logical device that destroys the render pass.

  • renderPass is the handle of the render pass to destroy.

  • pAllocator controls host memory allocation as described in the Memory Allocation chapter.

Valid Usage
  • All submitted commands that refer to renderPass must have completed execution

  • If VkAllocationCallbacks were provided when renderPass was created, a compatible set of callbacks must be provided here

  • If no VkAllocationCallbacks were provided when renderPass was created, pAllocator must be NULL

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • If renderPass is not VK_NULL_HANDLE, renderPass must be a valid VkRenderPass handle

  • If pAllocator is not NULL, pAllocator must be a valid pointer to a valid VkAllocationCallbacks structure

  • If renderPass is a valid handle, it must have been created, allocated, or retrieved from device

Host Synchronization
  • Host access to renderPass must be externally synchronized

7.2. Render Pass Compatibility

Framebuffers and graphics pipelines are created based on a specific render pass object. They must only be used with that render pass object, or one compatible with it.

Two attachment references are compatible if they have matching format and sample count, or are both VK_ATTACHMENT_UNUSED or the pointer that would contain the reference is NULL.

Two arrays of attachment references are compatible if all corresponding pairs of attachments are compatible. If the arrays are of different lengths, attachment references not present in the smaller array are treated as VK_ATTACHMENT_UNUSED.

Two render passes are compatible if their corresponding color, input, resolve, and depth/stencil attachment references are compatible and if they are otherwise identical except for:

  • Initial and final image layout in attachment descriptions

  • Load and store operations in attachment descriptions

  • Image layout in attachment references

A framebuffer is compatible with a render pass if it was created using the same render pass or a compatible render pass.

7.3. Framebuffers

Render passes operate in conjunction with framebuffers. Framebuffers represent a collection of specific memory attachments that a render pass instance uses.

Framebuffers are represented by VkFramebuffer handles:

VK_DEFINE_NON_DISPATCHABLE_HANDLE(VkFramebuffer)

To create a framebuffer, call:

VkResult vkCreateFramebuffer(
    VkDevice                                    device,
    const VkFramebufferCreateInfo*              pCreateInfo,
    const VkAllocationCallbacks*                pAllocator,
    VkFramebuffer*                              pFramebuffer);
  • device is the logical device that creates the framebuffer.

  • pCreateInfo points to a VkFramebufferCreateInfo structure which describes additional information about framebuffer creation.

  • pAllocator controls host memory allocation as described in the Memory Allocation chapter.

  • pFramebuffer points to a VkFramebuffer handle in which the resulting framebuffer object is returned.

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • pCreateInfo must be a valid pointer to a valid VkFramebufferCreateInfo structure

  • If pAllocator is not NULL, pAllocator must be a valid pointer to a valid VkAllocationCallbacks structure

  • pFramebuffer must be a valid pointer to a VkFramebuffer handle

Return Codes
Success
  • VK_SUCCESS

Failure
  • VK_ERROR_OUT_OF_HOST_MEMORY

  • VK_ERROR_OUT_OF_DEVICE_MEMORY

The VkFramebufferCreateInfo structure is defined as:

typedef struct VkFramebufferCreateInfo {
    VkStructureType             sType;
    const void*                 pNext;
    VkFramebufferCreateFlags    flags;
    VkRenderPass                renderPass;
    uint32_t                    attachmentCount;
    const VkImageView*          pAttachments;
    uint32_t                    width;
    uint32_t                    height;
    uint32_t                    layers;
} VkFramebufferCreateInfo;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • flags is reserved for future use.

  • renderPass is a render pass that defines what render passes the framebuffer will be compatible with. See Render Pass Compatibility for details.

  • attachmentCount is the number of attachments.

  • pAttachments is an array of VkImageView handles, each of which will be used as the corresponding attachment in a render pass instance.

  • width, height and layers define the dimensions of the framebuffer. If the render pass uses multiview, then layers must be one and each attachment requires a number of layers that is greater than the maximum bit index set in the view mask in the subpasses in which it is used.

Applications must ensure that all accesses to memory that backs image subresources used as attachments in a given renderpass instance either happen-before the load operations for those attachments, or happen-after the store operations for those attachments.

For depth/stencil attachments, each aspect can be used separately as attachments and non-attachments as long as the non-attachment accesses are also via an image subresource in either the VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMAL layout or the VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_OPTIMAL layout, and the attachment resource uses whichever of those two layouts the image accesses do not. Use of non-attachment aspects in this case is only well defined if the attachment is used in the subpass where the non-attachment access is being made, or the layout of the image subresource is constant throughout the entire render pass instance, including the initialLayout and finalLayout.

Note

These restrictions mean that the render pass has full knowledge of all uses of all of the attachments, so that the implementation is able to make correct decisions about when and how to perform layout transitions, when to overlap execution of subpasses, etc.

It is legal for a subpass to use no color or depth/stencil attachments, and rather use shader side effects such as image stores and atomics to produce an output. In this case, the subpass continues to use the width, height, and layers of the framebuffer to define the dimensions of the rendering area, and the rasterizationSamples from each pipeline’s VkPipelineMultisampleStateCreateInfo to define the number of samples used in rasterization; however, if VkPhysicalDeviceFeatures::variableMultisampleRate is VK_FALSE, then all pipelines to be bound with a given zero-attachment subpass must have the same value for VkPipelineMultisampleStateCreateInfo::rasterizationSamples.

Valid Usage
  • attachmentCount must be equal to the attachment count specified in renderPass

  • Each element of pAttachments that is used as a color attachment or resolve attachment by renderPass must have been created with a usage value including VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT

  • Each element of pAttachments that is used as a depth/stencil attachment by renderPass must have been created with a usage value including VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT

  • Each element of pAttachments that is used as an input attachment by renderPass must have been created with a usage value including VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT

  • Each element of pAttachments must have been created with an VkFormat value that matches the VkFormat specified by the corresponding VkAttachmentDescription in renderPass

  • Each element of pAttachments must have been created with a samples value that matches the samples value specified by the corresponding VkAttachmentDescription in renderPass

  • Each element of pAttachments must have dimensions at least as large as the corresponding framebuffer dimension

  • Each element of pAttachments must only specify a single mip level

  • Each element of pAttachments must have been created with the identity swizzle

  • width must be greater than 0.

  • width must be less than or equal to VkPhysicalDeviceLimits::maxFramebufferWidth

  • height must be greater than 0.

  • height must be less than or equal to VkPhysicalDeviceLimits::maxFramebufferHeight

  • layers must be greater than 0.

  • layers must be less than or equal to VkPhysicalDeviceLimits::maxFramebufferLayers

  • Each element of pAttachments that is a 2D or 2D array image view taken from a 3D image must not be a depth/stencil format

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO

  • pNext must be NULL

  • flags must be 0

  • renderPass must be a valid VkRenderPass handle

  • If attachmentCount is not 0, pAttachments must be a valid pointer to an array of attachmentCount valid VkImageView handles

  • Both of renderPass, and the elements of pAttachments that are valid handles must have been created, allocated, or retrieved from the same VkDevice

typedef VkFlags VkFramebufferCreateFlags;

VkFramebufferCreateFlags is a bitmask type for setting a mask, but is currently reserved for future use.

To destroy a framebuffer, call:

void vkDestroyFramebuffer(
    VkDevice                                    device,
    VkFramebuffer                               framebuffer,
    const VkAllocationCallbacks*                pAllocator);
  • device is the logical device that destroys the framebuffer.

  • framebuffer is the handle of the framebuffer to destroy.

  • pAllocator controls host memory allocation as described in the Memory Allocation chapter.

Valid Usage
  • All submitted commands that refer to framebuffer must have completed execution

  • If VkAllocationCallbacks were provided when framebuffer was created, a compatible set of callbacks must be provided here

  • If no VkAllocationCallbacks were provided when framebuffer was created, pAllocator must be NULL

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • If framebuffer is not VK_NULL_HANDLE, framebuffer must be a valid VkFramebuffer handle

  • If pAllocator is not NULL, pAllocator must be a valid pointer to a valid VkAllocationCallbacks structure

  • If framebuffer is a valid handle, it must have been created, allocated, or retrieved from device

Host Synchronization
  • Host access to framebuffer must be externally synchronized

7.4. Render Pass Commands

An application records the commands for a render pass instance one subpass at a time, by beginning a render pass instance, iterating over the subpasses to record commands for that subpass, and then ending the render pass instance.

To begin a render pass instance, call:

void vkCmdBeginRenderPass(
    VkCommandBuffer                             commandBuffer,
    const VkRenderPassBeginInfo*                pRenderPassBegin,
    VkSubpassContents                           contents);
  • commandBuffer is the command buffer in which to record the command.

  • pRenderPassBegin is a pointer to a VkRenderPassBeginInfo structure (defined below) which specifies the render pass to begin an instance of, and the framebuffer the instance uses.

  • contents is a VkSubpassContents value specifying how the commands in the first subpass will be provided.

After beginning a render pass instance, the command buffer is ready to record the commands for the first subpass of that render pass.

Valid Usage
  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL, or VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_SAMPLED_BIT or VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_TRANSFER_SRC_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_TRANSFER_DST_BIT set

  • If any of the initialLayout members of the VkAttachmentDescription structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is not VK_IMAGE_LAYOUT_UNDEFINED, then each such initialLayout must be equal to the current layout of the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin

  • The srcStageMask and dstStageMask members of any element of the pDependencies member of VkRenderPassCreateInfo used to create renderPass must be supported by the capabilities of the queue family identified by the queueFamilyIndex member of the VkCommandPoolCreateInfo used to create the command pool which commandBuffer was allocated from.

Valid Usage (Implicit)
  • commandBuffer must be a valid VkCommandBuffer handle

  • pRenderPassBegin must be a valid pointer to a valid VkRenderPassBeginInfo structure

  • contents must be a valid VkSubpassContents value

  • commandBuffer must be in the recording state

  • The VkCommandPool that commandBuffer was allocated from must support graphics operations

  • This command must only be called outside of a render pass instance

  • commandBuffer must be a primary VkCommandBuffer

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

  • Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type

Primary

Outside

Graphics

Graphics

Alternatively to begin a render pass, call:

void vkCmdBeginRenderPass2KHR(
    VkCommandBuffer                             commandBuffer,
    const VkRenderPassBeginInfo*                pRenderPassBegin,
    const VkSubpassBeginInfoKHR*                pSubpassBeginInfo);
  • commandBuffer is the command buffer in which to record the command.

  • pRenderPassBegin is a pointer to a VkRenderPassBeginInfo structure (defined below) which indicates the render pass to begin an instance of, and the framebuffer the instance uses.

  • pSubpassBeginInfo is a pointer to a VkSubpassBeginInfoKHR structure which contains information about the subpass which is about to begin rendering.

After beginning a render pass instance, the command buffer is ready to record the commands for the first subpass of that render pass.

Valid Usage
  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL, or VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_SAMPLED_BIT or VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_TRANSFER_SRC_BIT set

  • If any of the initialLayout or finalLayout member of the VkAttachmentDescription structures or the layout member of the VkAttachmentReference structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin must have been created with VK_IMAGE_USAGE_TRANSFER_DST_BIT set

  • If any of the initialLayout members of the VkAttachmentDescription structures specified when creating the render pass specified in the renderPass member of pRenderPassBegin is not VK_IMAGE_LAYOUT_UNDEFINED, then each such initialLayout must be equal to the current layout of the corresponding attachment image subresource of the framebuffer specified in the framebuffer member of pRenderPassBegin

  • The srcStageMask and dstStageMask members of any element of the pDependencies member of VkRenderPassCreateInfo used to create renderPass must be supported by the capabilities of the queue family identified by the queueFamilyIndex member of the VkCommandPoolCreateInfo used to create the command pool which commandBuffer was allocated from.

Valid Usage (Implicit)
  • commandBuffer must be a valid VkCommandBuffer handle

  • pRenderPassBegin must be a valid pointer to a valid VkRenderPassBeginInfo structure

  • pSubpassBeginInfo must be a valid pointer to a valid VkSubpassBeginInfoKHR structure

  • commandBuffer must be in the recording state

  • The VkCommandPool that commandBuffer was allocated from must support graphics operations

  • This command must only be called outside of a render pass instance

  • commandBuffer must be a primary VkCommandBuffer

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

  • Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type

Primary

Outside

Graphics

Graphics

The VkRenderPassBeginInfo structure is defined as:

typedef struct VkRenderPassBeginInfo {
    VkStructureType        sType;
    const void*            pNext;
    VkRenderPass           renderPass;
    VkFramebuffer          framebuffer;
    VkRect2D               renderArea;
    uint32_t               clearValueCount;
    const VkClearValue*    pClearValues;
} VkRenderPassBeginInfo;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • renderPass is the render pass to begin an instance of.

  • framebuffer is the framebuffer containing the attachments that are used with the render pass.

  • renderArea is the render area that is affected by the render pass instance, and is described in more detail below.

  • clearValueCount is the number of elements in pClearValues.

  • pClearValues is an array of VkClearValue structures that contains clear values for each attachment, if the attachment uses a loadOp value of VK_ATTACHMENT_LOAD_OP_CLEAR or if the attachment has a depth/stencil format and uses a stencilLoadOp value of VK_ATTACHMENT_LOAD_OP_CLEAR. The array is indexed by attachment number. Only elements corresponding to cleared attachments are used. Other elements of pClearValues are ignored.

renderArea is the render area that is affected by the render pass instance. The effects of attachment load, store and multisample resolve operations are restricted to the pixels whose x and y coordinates fall within the render area on all attachments. The render area extends to all layers of framebuffer. The application must ensure (using scissor if necessary) that all rendering is contained within the render area, otherwise the pixels outside of the render area become undefined and shader side effects may occur for fragments outside the render area. The render area must be contained within the framebuffer dimensions.

When multiview is enabled, the resolve operation at the end of a subpass applies to all views in the view mask.

Note

There may be a performance cost for using a render area smaller than the framebuffer, unless it matches the render area granularity for the render pass.

Valid Usage
  • clearValueCount must be greater than the largest attachment index in renderPass that specifies a loadOp (or stencilLoadOp, if the attachment has a depth/stencil format) of VK_ATTACHMENT_LOAD_OP_CLEAR

  • If clearValueCount is not 0, pClearValues must be a valid pointer to an array of clearValueCount valid VkClearValue unions

  • renderPass must be compatible with the renderPass member of the VkFramebufferCreateInfo structure specified when creating framebuffer.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO

  • Each pNext member of any structure (including this one) in the pNext chain must be either NULL or a pointer to a valid instance of VkDeviceGroupRenderPassBeginInfo or VkRenderPassSampleLocationsBeginInfoEXT

  • Each sType member in the pNext chain must be unique

  • renderPass must be a valid VkRenderPass handle

  • framebuffer must be a valid VkFramebuffer handle

  • Both of framebuffer, and renderPass must have been created, allocated, or retrieved from the same VkDevice

The image layout of the depth aspect of a depth/stencil attachment referring to an image created with VK_IMAGE_CREATE_SAMPLE_LOCATIONS_COMPATIBLE_DEPTH_BIT_EXT is dependent on the last sample locations used to render to the image subresource, thus preserving the contents of such depth/stencil attachments across subpass boundaries requires the application to specify these sample locations whenever a layout transition of the attachment may occur. This information can be provided by chaining an instance of the VkRenderPassSampleLocationsBeginInfoEXT structure to the pNext chain of VkRenderPassBeginInfo.

The VkRenderPassSampleLocationsBeginInfoEXT structure is defined as:

typedef struct VkRenderPassSampleLocationsBeginInfoEXT {
    VkStructureType                          sType;
    const void*                              pNext;
    uint32_t                                 attachmentInitialSampleLocationsCount;
    const VkAttachmentSampleLocationsEXT*    pAttachmentInitialSampleLocations;
    uint32_t                                 postSubpassSampleLocationsCount;
    const VkSubpassSampleLocationsEXT*       pPostSubpassSampleLocations;
} VkRenderPassSampleLocationsBeginInfoEXT;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • attachmentInitialSampleLocationsCount is the number of elements in the pAttachmentInitialSampleLocations array.

  • pAttachmentInitialSampleLocations is an array of attachmentInitialSampleLocationsCount VkAttachmentSampleLocationsEXT structures specifying the attachment indices and their corresponding sample location state. Each element of pAttachmentInitialSampleLocations can specify the sample location state to use in the automatic layout transition performed to transition a depth/stencil attachment from the initial layout of the attachment to the image layout specified for the attachment in the first subpass using it.

  • postSubpassSampleLocationsCount is the number of elements in the pPostSubpassSampleLocations array.

  • pPostSubpassSampleLocations is an array of postSubpassSampleLocationsCount VkSubpassSampleLocationsEXT structures specifying the subpass indices and their corresponding sample location state. Each element of pPostSubpassSampleLocations can specify the sample location state to use in the automatic layout transition performed to transition the depth/stencil attachment used by the specified subpass to the image layout specified in a dependent subpass or to the final layout of the attachment in case the specified subpass is the last subpass using that attachment. In addition, if VkPhysicalDeviceSampleLocationsPropertiesEXT::variableSampleLocations is VK_FALSE, each element of pPostSubpassSampleLocations must specify the sample location state that matches the sample locations used by all pipelines that will be bound to a command buffer during the specified subpass. If variableSampleLocations is VK_TRUE, the sample locations used for rasterization do not depend on pPostSubpassSampleLocations.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_RENDER_PASS_SAMPLE_LOCATIONS_BEGIN_INFO_EXT

  • If attachmentInitialSampleLocationsCount is not 0, pAttachmentInitialSampleLocations must be a valid pointer to an array of attachmentInitialSampleLocationsCount valid VkAttachmentSampleLocationsEXT structures

  • If postSubpassSampleLocationsCount is not 0, pPostSubpassSampleLocations must be a valid pointer to an array of postSubpassSampleLocationsCount valid VkSubpassSampleLocationsEXT structures

The VkAttachmentSampleLocationsEXT structure is defined as:

typedef struct VkAttachmentSampleLocationsEXT {
    uint32_t                    attachmentIndex;
    VkSampleLocationsInfoEXT    sampleLocationsInfo;
} VkAttachmentSampleLocationsEXT;
  • attachmentIndex is the index of the attachment for which the sample locations state is provided.

  • sampleLocationsInfo is the sample locations state to use for the layout transition of the given attachment from the initial layout of the attachment to the image layout specified for the attachment in the first subpass using it.

If the image referenced by the framebuffer attachment at index attachmentIndex was not created with VK_IMAGE_CREATE_SAMPLE_LOCATIONS_COMPATIBLE_DEPTH_BIT_EXT then the values specified in sampleLocationsInfo are ignored.

Valid Usage
Valid Usage (Implicit)
  • sampleLocationsInfo must be a valid VkSampleLocationsInfoEXT structure

The VkSubpassSampleLocationsEXT structure is defined as:

typedef struct VkSubpassSampleLocationsEXT {
    uint32_t                    subpassIndex;
    VkSampleLocationsInfoEXT    sampleLocationsInfo;
} VkSubpassSampleLocationsEXT;
  • subpassIndex is the index of the subpass for which the sample locations state is provided.

  • sampleLocationsInfo is the sample locations state to use for the layout transition of the depth/stencil attachment away from the image layout the attachment is used with in the subpass specified in subpassIndex.

If the image referenced by the depth/stencil attachment used in the subpass identified by subpassIndex was not created with VK_IMAGE_CREATE_SAMPLE_LOCATIONS_COMPATIBLE_DEPTH_BIT_EXT or if the subpass does not use a depth/stencil attachment, and VkPhysicalDeviceSampleLocationsPropertiesEXT::variableSampleLocations is VK_TRUE then the values specified in sampleLocationsInfo are ignored.

Valid Usage
Valid Usage (Implicit)
  • sampleLocationsInfo must be a valid VkSampleLocationsInfoEXT structure

The VkSubpassBeginInfoKHR structure is defined as:

typedef struct VkSubpassBeginInfoKHR {
    VkStructureType      sType;
    const void*          pNext;
    VkSubpassContents    contents;
} VkSubpassBeginInfoKHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • contents is a VkSubpassContents value specifying how the commands in the next subpass will be provided.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_SUBPASS_BEGIN_INFO_KHR

  • pNext must be NULL

  • contents must be a valid VkSubpassContents value

Possible values of vkCmdBeginRenderPass::contents, specifying how the commands in the first subpass will be provided, are:

typedef enum VkSubpassContents {
    VK_SUBPASS_CONTENTS_INLINE = 0,
    VK_SUBPASS_CONTENTS_SECONDARY_COMMAND_BUFFERS = 1,
} VkSubpassContents;
  • VK_SUBPASS_CONTENTS_INLINE specifies that the contents of the subpass will be recorded inline in the primary command buffer, and secondary command buffers must not be executed within the subpass.

  • VK_SUBPASS_CONTENTS_SECONDARY_COMMAND_BUFFERS specifies that the contents are recorded in secondary command buffers that will be called from the primary command buffer, and vkCmdExecuteCommands is the only valid command on the command buffer until vkCmdNextSubpass or vkCmdEndRenderPass.

If the pNext chain of VkRenderPassBeginInfo includes a VkDeviceGroupRenderPassBeginInfo structure, then that structure includes a device mask and set of render areas for the render pass instance.

The VkDeviceGroupRenderPassBeginInfo structure is defined as:

typedef struct VkDeviceGroupRenderPassBeginInfo {
    VkStructureType    sType;
    const void*        pNext;
    uint32_t           deviceMask;
    uint32_t           deviceRenderAreaCount;
    const VkRect2D*    pDeviceRenderAreas;
} VkDeviceGroupRenderPassBeginInfo;

or the equivalent

typedef VkDeviceGroupRenderPassBeginInfo VkDeviceGroupRenderPassBeginInfoKHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

  • deviceMask is the device mask for the render pass instance.

  • deviceRenderAreaCount is the number of elements in the pDeviceRenderAreas array.

  • pDeviceRenderAreas is an array of structures of type VkRect2D defining the render area for each physical device.

The deviceMask serves several purposes. It is an upper bound on the set of physical devices that can be used during the render pass instance, and the initial device mask when the render pass instance begins. Render pass attachment load, store, and resolve operations only apply to physical devices included in the device mask. Subpass dependencies only apply to the physical devices in the device mask.

If deviceRenderAreaCount is not zero, then the elements of pDeviceRenderAreas override the value of VkRenderPassBeginInfo::renderArea, and provide a render area specific to each physical device. These render areas serve the same purpose as VkRenderPassBeginInfo::renderArea, including controlling the region of attachments that are cleared by VK_ATTACHMENT_LOAD_OP_CLEAR and that are resolved into resolve attachments.

If this structure is not present, the render pass instance’s device mask is the value of VkDeviceGroupCommandBufferBeginInfo::deviceMask. If this structure is not present or if deviceRenderAreaCount is zero, VkRenderPassBeginInfo::renderArea is used for all physical devices.

Valid Usage
  • deviceMask must be a valid device mask value

  • deviceMask must not be zero

  • deviceMask must be a subset of the command buffer’s initial device mask

  • deviceRenderAreaCount must either be zero or equal to the number of physical devices in the logical device.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_DEVICE_GROUP_RENDER_PASS_BEGIN_INFO

  • If deviceRenderAreaCount is not 0, pDeviceRenderAreas must be a valid pointer to an array of deviceRenderAreaCount VkRect2D structures

To query the render area granularity, call:

void vkGetRenderAreaGranularity(
    VkDevice                                    device,
    VkRenderPass                                renderPass,
    VkExtent2D*                                 pGranularity);
  • device is the logical device that owns the render pass.

  • renderPass is a handle to a render pass.

  • pGranularity points to a VkExtent2D structure in which the granularity is returned.

The conditions leading to an optimal renderArea are:

  • the offset.x member in renderArea is a multiple of the width member of the returned VkExtent2D (the horizontal granularity).

  • the offset.y member in renderArea is a multiple of the height of the returned VkExtent2D (the vertical granularity).

  • either the offset.width member in renderArea is a multiple of the horizontal granularity or offset.x+offset.width is equal to the width of the framebuffer in the VkRenderPassBeginInfo.

  • either the offset.height member in renderArea is a multiple of the vertical granularity or offset.y+offset.height is equal to the height of the framebuffer in the VkRenderPassBeginInfo.

Subpass dependencies are not affected by the render area, and apply to the entire image subresources attached to the framebuffer as specified in the description of automatic layout transitions. Similarly, pipeline barriers are valid even if their effect extends outside the render area.

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • renderPass must be a valid VkRenderPass handle

  • pGranularity must be a valid pointer to a VkExtent2D structure

  • renderPass must have been created, allocated, or retrieved from device

To transition to the next subpass in the render pass instance after recording the commands for a subpass, call:

void vkCmdNextSubpass(
    VkCommandBuffer                             commandBuffer,
    VkSubpassContents                           contents);
  • commandBuffer is the command buffer in which to record the command.

  • contents specifies how the commands in the next subpass will be provided, in the same fashion as the corresponding parameter of vkCmdBeginRenderPass.

The subpass index for a render pass begins at zero when vkCmdBeginRenderPass is recorded, and increments each time vkCmdNextSubpass is recorded.

Moving to the next subpass automatically performs any multisample resolve operations in the subpass being ended. End-of-subpass multisample resolves are treated as color attachment writes for the purposes of synchronization. That is, they are considered to execute in the VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT pipeline stage and their writes are synchronized with VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT. Synchronization between rendering within a subpass and any resolve operations at the end of the subpass occurs automatically, without need for explicit dependencies or pipeline barriers. However, if the resolve attachment is also used in a different subpass, an explicit dependency is needed.

After transitioning to the next subpass, the application can record the commands for that subpass.

Valid Usage
  • The current subpass index must be less than the number of subpasses in the render pass minus one

Valid Usage (Implicit)
  • commandBuffer must be a valid VkCommandBuffer handle

  • contents must be a valid VkSubpassContents value

  • commandBuffer must be in the recording state

  • The VkCommandPool that commandBuffer was allocated from must support graphics operations

  • This command must only be called inside of a render pass instance

  • commandBuffer must be a primary VkCommandBuffer

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

  • Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type

Primary

Inside

Graphics

Graphics

To transition to the next subpass in the render pass instance after recording the commands for a subpass, call:

void vkCmdNextSubpass2KHR(
    VkCommandBuffer                             commandBuffer,
    const VkSubpassBeginInfoKHR*                pSubpassBeginInfo,
    const VkSubpassEndInfoKHR*                  pSubpassEndInfo);
  • commandBuffer is the command buffer in which to record the command.

  • pSubpassBeginInfo is a pointer to a VkSubpassBeginInfoKHR structure which contains information about the subpass which is about to begin rendering.

  • pSubpassEndInfo is a pointer to a VkSubpassEndInfoKHR structure which contains information about how the previous subpass will be ended.

vkCmdNextSubpass2KHR is semantically identical to vkCmdNextSubpass, except that it is extensible, and that contents is provided as part of an extensible structure instead of as a flat parameter.

Valid Usage
  • The current subpass index must be less than the number of subpasses in the render pass minus one

Valid Usage (Implicit)
  • commandBuffer must be a valid VkCommandBuffer handle

  • pSubpassBeginInfo must be a valid pointer to a valid VkSubpassBeginInfoKHR structure

  • pSubpassEndInfo must be a valid pointer to a valid VkSubpassEndInfoKHR structure

  • commandBuffer must be in the recording state

  • The VkCommandPool that commandBuffer was allocated from must support graphics operations

  • This command must only be called inside of a render pass instance

  • commandBuffer must be a primary VkCommandBuffer

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

  • Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type

Primary

Inside

Graphics

Graphics

To record a command to end a render pass instance after recording the commands for the last subpass, call:

void vkCmdEndRenderPass(
    VkCommandBuffer                             commandBuffer);
  • commandBuffer is the command buffer in which to end the current render pass instance.

Ending a render pass instance performs any multisample resolve operations on the final subpass.

Valid Usage
  • The current subpass index must be equal to the number of subpasses in the render pass minus one

Valid Usage (Implicit)
  • commandBuffer must be a valid VkCommandBuffer handle

  • commandBuffer must be in the recording state

  • The VkCommandPool that commandBuffer was allocated from must support graphics operations

  • This command must only be called inside of a render pass instance

  • commandBuffer must be a primary VkCommandBuffer

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

  • Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type

Primary

Inside

Graphics

Graphics

To record a command to end a render pass instance after recording the commands for the last subpass, call:

void vkCmdEndRenderPass2KHR(
    VkCommandBuffer                             commandBuffer,
    const VkSubpassEndInfoKHR*                  pSubpassEndInfo);
  • commandBuffer is the command buffer in which to end the current render pass instance.

  • pSubpassEndInfo is a pointer to a VkSubpassEndInfoKHR structure which contains information about how the previous subpass will be ended.

vkCmdEndRenderPass2KHR is semantically identical to vkCmdEndRenderPass, except that it is extensible.

Valid Usage
  • The current subpass index must be equal to the number of subpasses in the render pass minus one

Valid Usage (Implicit)
  • commandBuffer must be a valid VkCommandBuffer handle

  • pSubpassEndInfo must be a valid pointer to a valid VkSubpassEndInfoKHR structure

  • commandBuffer must be in the recording state

  • The VkCommandPool that commandBuffer was allocated from must support graphics operations

  • This command must only be called inside of a render pass instance

  • commandBuffer must be a primary VkCommandBuffer

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

  • Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type

Primary

Inside

Graphics

Graphics

The VkSubpassEndInfoKHR structure is defined as:

typedef struct VkSubpassEndInfoKHR {
    VkStructureType    sType;
    const void*        pNext;
} VkSubpassEndInfoKHR;
  • sType is the type of this structure.

  • pNext is NULL or a pointer to an extension-specific structure.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_SUBPASS_END_INFO_KHR

  • pNext must be NULL