10. Pipelines
The following figure shows a block diagram of the Vulkan pipelines. Some Vulkan commands specify geometric objects to be drawn or computational work to be performed, while others specify state controlling how objects are handled by the various pipeline stages, or control data transfer between memory organized as images and buffers. Commands are effectively sent through a processing pipeline, either a graphics pipeline, or a compute pipeline.
The first stage of the graphics pipeline (Input Assembler) assembles vertices to form geometric primitives such as points, lines, and triangles, based on a requested primitive topology. In the next stage (Vertex Shader) vertices can be transformed, computing positions and attributes for each vertex. If tessellation and/or geometry shaders are supported, they can then generate multiple primitives from a single input primitive, possibly changing the primitive topology or generating additional attribute data in the process.
The final resulting primitives are clipped to a clip volume in preparation for the next stage, Rasterization. The rasterizer produces a series of fragments associated with a region of the framebuffer, from a two-dimensional description of a point, line segment, or triangle. These fragments are processed by fragment operations to determine whether generated values will be written to the framebuffer. Fragment shading determines the values to be written to the framebuffer attachments. Framebuffer operations then read and write the color and depth/stencil attachments of the framebuffer for a given subpass of a render pass instance. The attachments can be used as input attachments in the fragment shader in a later subpass of the same render pass.
The compute pipeline is a separate pipeline from the graphics pipeline, which operates on one-, two-, or three-dimensional workgroups which can read from and write to buffer and image memory.
This ordering is meant only as a tool for describing Vulkan, not as a strict rule of how Vulkan is implemented, and we present it only as a means to organize the various operations of the pipelines. Actual ordering guarantees between pipeline stages are explained in detail in the synchronization chapter.
Each pipeline is controlled by a monolithic object created from a description of all of the shader stages and any relevant fixed-function stages. Linking the whole pipeline together allows the optimization of shaders based on their input/outputs and eliminates expensive draw time state validation.
A pipeline object is bound to the current state using vkCmdBindPipeline. Any pipeline object state that is specified as dynamic is not applied to the current state when the pipeline object is bound, but is instead set by dynamic state setting commands.
No state, including dynamic state, is inherited from one command buffer to another.
Compute,
and graphics pipelines are each represented by VkPipeline handles:
// Provided by VK_VERSION_1_0
VK_DEFINE_NON_DISPATCHABLE_HANDLE(VkPipeline)10.1. Multiple Pipeline Creation
Multiple pipelines can be created in a single call by commands such as vkCreateComputePipelines, and vkCreateGraphicsPipelines.
The creation commands are passed an array pCreateInfos of
Vk*PipelineCreateInfo structures specifying parameters of each
pipeline to be created, and return a corresponding array of handles in
pPipelines.
Each element index i of pPipelines is created based on the
corresponding element i of pCreateInfos.
Applications can group together similar pipelines to be created in a single call, and implementations are encouraged to look for reuse opportunities when creating a group.
When attempting to create many pipelines in a single command, it is possible
that creation may fail for a subset of them.
In this case, the corresponding elements of pPipelines will be set to
VK_NULL_HANDLE.
If creation fails for a pipeline despite valid arguments (for example, due
to out of memory errors), the VkResult code returned by the pipeline
creation command will indicate why.
The implementation will attempt to create all pipelines, and only return
VK_NULL_HANDLE values for those that actually failed.
If creation fails for multiple pipelines, the returned VkResult must
be the return value of any one of the pipelines which did not succeed.
An application can reliably clean up from a failed call by iterating over
the pPipelines array and destroying every element that is not
VK_NULL_HANDLE.
If the entire command fails and no pipelines are created, all elements of
pPipelines will be set to VK_NULL_HANDLE.
10.2. Compute Pipelines
Compute pipelines consist of a single static compute shader stage and the pipeline layout.
The compute pipeline represents a compute shader and is created by calling
vkCreateComputePipelines
with module and pName selecting an entry point from a shader
module, where that entry point defines a valid compute shader, in the
VkPipelineShaderStageCreateInfo structure contained within the
VkComputePipelineCreateInfo structure.
To create compute pipelines, call:
// Provided by VK_VERSION_1_0
VkResult vkCreateComputePipelines(
VkDevice device,
VkPipelineCache pipelineCache,
uint32_t createInfoCount,
const VkComputePipelineCreateInfo* pCreateInfos,
const VkAllocationCallbacks* pAllocator,
VkPipeline* pPipelines);-
deviceis the logical device that creates the compute pipelines. -
pipelineCacheis either VK_NULL_HANDLE, indicating that pipeline caching is disabled; or the handle of a valid pipeline cache object, in which case use of that cache is enabled for the duration of the command. -
createInfoCountis the length of thepCreateInfosandpPipelinesarrays. -
pCreateInfosis a pointer to an array of VkComputePipelineCreateInfo structures. -
pAllocatorcontrols host memory allocation as described in the Memory Allocation chapter. -
pPipelinesis a pointer to an array of VkPipeline handles in which the resulting compute pipeline objects are returned.
Pipelines are created and returned as described for Multiple Pipeline Creation.
The VkComputePipelineCreateInfo structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkComputePipelineCreateInfo {
VkStructureType sType;
const void* pNext;
VkPipelineCreateFlags flags;
VkPipelineShaderStageCreateInfo stage;
VkPipelineLayout layout;
VkPipeline basePipelineHandle;
int32_t basePipelineIndex;
} VkComputePipelineCreateInfo;-
sTypeis a VkStructureType value identifying this structure. -
pNextisNULLor a pointer to a structure extending this structure. -
flagsis a bitmask of VkPipelineCreateFlagBits specifying how the pipeline will be generated. -
stageis a VkPipelineShaderStageCreateInfo structure describing the compute shader. -
layoutis the description of binding locations used by both the pipeline and descriptor sets used with the pipeline. -
basePipelineHandleis a pipeline to derive from. -
basePipelineIndexis an index into thepCreateInfosparameter to use as a pipeline to derive from.
The parameters basePipelineHandle and basePipelineIndex are
described in more detail in Pipeline
Derivatives.
The VkPipelineShaderStageCreateInfo structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkPipelineShaderStageCreateInfo {
VkStructureType sType;
const void* pNext;
VkPipelineShaderStageCreateFlags flags;
VkShaderStageFlagBits stage;
VkShaderModule module;
const char* pName;
const VkSpecializationInfo* pSpecializationInfo;
} VkPipelineShaderStageCreateInfo;-
sTypeis a VkStructureType value identifying this structure. -
pNextisNULLor a pointer to a structure extending this structure. -
flagsis a bitmask of VkPipelineShaderStageCreateFlagBits specifying how the pipeline shader stage will be generated. -
stageis a VkShaderStageFlagBits value specifying a single pipeline stage. -
moduleis a VkShaderModule object containing the shader code for this stage. -
pNameis a pointer to a null-terminated UTF-8 string specifying the entry point name of the shader for this stage. -
pSpecializationInfois a pointer to a VkSpecializationInfo structure, as described in Specialization Constants, orNULL.
The shader code used by the pipeline is defined by module.
// Provided by VK_VERSION_1_0
typedef VkFlags VkPipelineShaderStageCreateFlags;VkPipelineShaderStageCreateFlags is a bitmask type for setting a mask
of zero or more VkPipelineShaderStageCreateFlagBits.
Possible values of the flags member of
VkPipelineShaderStageCreateInfo specifying how a pipeline shader stage
is created, are:
// Provided by VK_VERSION_1_0
typedef enum VkPipelineShaderStageCreateFlagBits {
} VkPipelineShaderStageCreateFlagBits;Bits which can be set by commands and structures, specifying one or more shader stages, are:
// Provided by VK_VERSION_1_0
typedef enum VkShaderStageFlagBits {
VK_SHADER_STAGE_VERTEX_BIT = 0x00000001,
VK_SHADER_STAGE_TESSELLATION_CONTROL_BIT = 0x00000002,
VK_SHADER_STAGE_TESSELLATION_EVALUATION_BIT = 0x00000004,
VK_SHADER_STAGE_GEOMETRY_BIT = 0x00000008,
VK_SHADER_STAGE_FRAGMENT_BIT = 0x00000010,
VK_SHADER_STAGE_COMPUTE_BIT = 0x00000020,
VK_SHADER_STAGE_ALL_GRAPHICS = 0x0000001F,
VK_SHADER_STAGE_ALL = 0x7FFFFFFF,
} VkShaderStageFlagBits;-
VK_SHADER_STAGE_VERTEX_BITspecifies the vertex stage. -
VK_SHADER_STAGE_TESSELLATION_CONTROL_BITspecifies the tessellation control stage. -
VK_SHADER_STAGE_TESSELLATION_EVALUATION_BITspecifies the tessellation evaluation stage. -
VK_SHADER_STAGE_GEOMETRY_BITspecifies the geometry stage. -
VK_SHADER_STAGE_FRAGMENT_BITspecifies the fragment stage. -
VK_SHADER_STAGE_COMPUTE_BITspecifies the compute stage. -
VK_SHADER_STAGE_ALL_GRAPHICSis a combination of bits used as shorthand to specify all graphics stages defined above (excluding the compute stage). -
VK_SHADER_STAGE_ALLis a combination of bits used as shorthand to specify all shader stages supported by the device, including all additional stages which are introduced by extensions.
|
Note
|
// Provided by VK_VERSION_1_0
typedef VkFlags VkShaderStageFlags;VkShaderStageFlags is a bitmask type for setting a mask of zero or
more VkShaderStageFlagBits.
10.3. Graphics Pipelines
Graphics pipelines consist of multiple shader stages, multiple fixed-function pipeline stages, and a pipeline layout.
To create graphics pipelines, call:
// Provided by VK_VERSION_1_0
VkResult vkCreateGraphicsPipelines(
VkDevice device,
VkPipelineCache pipelineCache,
uint32_t createInfoCount,
const VkGraphicsPipelineCreateInfo* pCreateInfos,
const VkAllocationCallbacks* pAllocator,
VkPipeline* pPipelines);-
deviceis the logical device that creates the graphics pipelines. -
pipelineCacheis either VK_NULL_HANDLE, indicating that pipeline caching is disabled; or the handle of a valid pipeline cache object, in which case use of that cache is enabled for the duration of the command. -
createInfoCountis the length of thepCreateInfosandpPipelinesarrays. -
pCreateInfosis a pointer to an array of VkGraphicsPipelineCreateInfo structures. -
pAllocatorcontrols host memory allocation as described in the Memory Allocation chapter. -
pPipelinesis a pointer to an array of VkPipeline handles in which the resulting graphics pipeline objects are returned.
The VkGraphicsPipelineCreateInfo structure includes an array of VkPipelineShaderStageCreateInfo structures for each of the desired active shader stages, as well as creation information for all relevant fixed-function stages, and a pipeline layout.
Pipelines are created and returned as described for Multiple Pipeline Creation.
The VkGraphicsPipelineCreateInfo structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkGraphicsPipelineCreateInfo {
VkStructureType sType;
const void* pNext;
VkPipelineCreateFlags flags;
uint32_t stageCount;
const VkPipelineShaderStageCreateInfo* pStages;
const VkPipelineVertexInputStateCreateInfo* pVertexInputState;
const VkPipelineInputAssemblyStateCreateInfo* pInputAssemblyState;
const VkPipelineTessellationStateCreateInfo* pTessellationState;
const VkPipelineViewportStateCreateInfo* pViewportState;
const VkPipelineRasterizationStateCreateInfo* pRasterizationState;
const VkPipelineMultisampleStateCreateInfo* pMultisampleState;
const VkPipelineDepthStencilStateCreateInfo* pDepthStencilState;
const VkPipelineColorBlendStateCreateInfo* pColorBlendState;
const VkPipelineDynamicStateCreateInfo* pDynamicState;
VkPipelineLayout layout;
VkRenderPass renderPass;
uint32_t subpass;
VkPipeline basePipelineHandle;
int32_t basePipelineIndex;
} VkGraphicsPipelineCreateInfo;-
sTypeis a VkStructureType value identifying this structure. -
pNextisNULLor a pointer to a structure extending this structure. -
flagsis a bitmask of VkPipelineCreateFlagBits specifying how the pipeline will be generated. -
stageCountis the number of entries in thepStagesarray. -
pStagesis a pointer to an array ofstageCountVkPipelineShaderStageCreateInfo structures describing the set of the shader stages to be included in the graphics pipeline. -
pVertexInputStateis a pointer to a VkPipelineVertexInputStateCreateInfo structure. -
pInputAssemblyStateis a pointer to a VkPipelineInputAssemblyStateCreateInfo structure which determines input assembly behavior for vertex shading, as described in Drawing Commands. -
pTessellationStateis a pointer to a VkPipelineTessellationStateCreateInfo structure defining tessellation state used by tessellation shaders. -
pViewportStateis a pointer to a VkPipelineViewportStateCreateInfo structure defining viewport state used when rasterization is enabled. -
pRasterizationStateis a pointer to a VkPipelineRasterizationStateCreateInfo structure defining rasterization state. -
pMultisampleStateis a pointer to a VkPipelineMultisampleStateCreateInfo structure defining multisample state used when rasterization is enabled. -
pDepthStencilStateis a pointer to a VkPipelineDepthStencilStateCreateInfo structure defining depth/stencil state used when rasterization is enabled for depth or stencil attachments accessed during rendering. -
pColorBlendStateis a pointer to a VkPipelineColorBlendStateCreateInfo structure defining color blend state used when rasterization is enabled for any color attachments accessed during rendering. -
pDynamicStateis a pointer to a VkPipelineDynamicStateCreateInfo structure defining which properties of the pipeline state object are dynamic and can be changed independently of the pipeline state. This can beNULL, which means no state in the pipeline is considered dynamic. -
layoutis the description of binding locations used by both the pipeline and descriptor sets used with the pipeline. -
renderPassis a handle to a render pass object describing the environment in which the pipeline will be used. The pipeline must only be used with a render pass instance compatible with the one provided. See Render Pass Compatibility for more information. -
subpassis the index of the subpass in the render pass where this pipeline will be used. -
basePipelineHandleis a pipeline to derive from. -
basePipelineIndexis an index into thepCreateInfosparameter to use as a pipeline to derive from.
The parameters basePipelineHandle and basePipelineIndex are
described in more detail in Pipeline
Derivatives.
The state required for a graphics pipeline is divided into vertex input state, pre-rasterization shader state, fragment shader state, and fragment output state.
Vertex input state is defined by:
This state must be specified to create a complete graphics pipeline.
Pre-rasterization shader state is defined by:
-
VkPipelineShaderStageCreateInfo entries for:
-
Vertex shaders
-
Tessellation control shaders
-
Tessellation evaluation shaders
-
Geometry shaders
-
-
Within the VkPipelineLayout, the full pipeline layout must be specified.
-
VkRenderPass and
subpassparameter
This state must be specified to create a complete graphics pipeline.
Fragment shader state is defined by:
-
A VkPipelineShaderStageCreateInfo entry for the fragment shader
-
Within the VkPipelineLayout, the full pipeline layout must be specified.
-
VkRenderPass and
subpassparameter
If
rasterizerDiscardEnable is set to VK_FALSE
this state must be specified to create a
complete graphics pipeline.
Fragment output state is defined by:
-
VkRenderPass and
subpassparameter
If
rasterizerDiscardEnable is set to VK_FALSE
this state must be specified to create a
complete graphics pipeline.
Dynamic state values set via pDynamicState must be ignored if the
state they correspond to is not otherwise statically set by one of the state
subsets used to create the pipeline.
For example, if a pipeline only included
pre-rasterization shader
state, then any dynamic state value corresponding to depth or stencil
testing has no effect.
A complete graphics pipeline always includes pre-rasterization shader state, with other subsets included depending on that state as specified in the above sections.
Bits which can be set in
-
VkGraphicsPipelineCreateInfo::
flags -
VkComputePipelineCreateInfo::
flags
specify how a pipeline is created, and are:
// Provided by VK_VERSION_1_0
typedef enum VkPipelineCreateFlagBits {
VK_PIPELINE_CREATE_DISABLE_OPTIMIZATION_BIT = 0x00000001,
VK_PIPELINE_CREATE_ALLOW_DERIVATIVES_BIT = 0x00000002,
VK_PIPELINE_CREATE_DERIVATIVE_BIT = 0x00000004,
// Provided by VK_VERSION_1_1
VK_PIPELINE_CREATE_VIEW_INDEX_FROM_DEVICE_INDEX_BIT = 0x00000008,
// Provided by VK_VERSION_1_1
VK_PIPELINE_CREATE_DISPATCH_BASE_BIT = 0x00000010,
// Provided by VK_VERSION_1_1
VK_PIPELINE_CREATE_DISPATCH_BASE = VK_PIPELINE_CREATE_DISPATCH_BASE_BIT,
} VkPipelineCreateFlagBits;-
VK_PIPELINE_CREATE_DISABLE_OPTIMIZATION_BITspecifies that the created pipeline will not be optimized. Using this flag may reduce the time taken to create the pipeline. -
VK_PIPELINE_CREATE_ALLOW_DERIVATIVES_BITspecifies that the pipeline to be created is allowed to be the parent of a pipeline that will be created in a subsequent pipeline creation call. -
VK_PIPELINE_CREATE_DERIVATIVE_BITspecifies that the pipeline to be created will be a child of a previously created parent pipeline. -
VK_PIPELINE_CREATE_VIEW_INDEX_FROM_DEVICE_INDEX_BITspecifies that any shader input variables decorated asViewIndexwill be assigned values as if they were decorated asDeviceIndex. -
VK_PIPELINE_CREATE_DISPATCH_BASEspecifies that a compute pipeline can be used with vkCmdDispatchBase with a non-zero base workgroup.
It is valid to set both VK_PIPELINE_CREATE_ALLOW_DERIVATIVES_BIT and
VK_PIPELINE_CREATE_DERIVATIVE_BIT.
This allows a pipeline to be both a parent and possibly a child in a
pipeline hierarchy.
See Pipeline Derivatives for more
information.
// Provided by VK_VERSION_1_0
typedef VkFlags VkPipelineCreateFlags;VkPipelineCreateFlags is a bitmask type for setting a mask of zero or
more VkPipelineCreateFlagBits.
The VkPipelineDynamicStateCreateInfo structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkPipelineDynamicStateCreateInfo {
VkStructureType sType;
const void* pNext;
VkPipelineDynamicStateCreateFlags flags;
uint32_t dynamicStateCount;
const VkDynamicState* pDynamicStates;
} VkPipelineDynamicStateCreateInfo;-
sTypeis a VkStructureType value identifying this structure. -
pNextisNULLor a pointer to a structure extending this structure. -
flagsis reserved for future use. -
dynamicStateCountis the number of elements in thepDynamicStatesarray. -
pDynamicStatesis a pointer to an array of VkDynamicState values specifying which pieces of pipeline state will use the values from dynamic state commands rather than from pipeline state creation information.
// Provided by VK_VERSION_1_0
typedef VkFlags VkPipelineDynamicStateCreateFlags;VkPipelineDynamicStateCreateFlags is a bitmask type for setting a
mask, but is currently reserved for future use.
The source of different pieces of dynamic state is specified by the
VkPipelineDynamicStateCreateInfo::pDynamicStates property of the
currently active pipeline, each of whose elements must be one of the
values:
// Provided by VK_VERSION_1_0
typedef enum VkDynamicState {
VK_DYNAMIC_STATE_VIEWPORT = 0,
VK_DYNAMIC_STATE_SCISSOR = 1,
VK_DYNAMIC_STATE_LINE_WIDTH = 2,
VK_DYNAMIC_STATE_DEPTH_BIAS = 3,
VK_DYNAMIC_STATE_BLEND_CONSTANTS = 4,
VK_DYNAMIC_STATE_DEPTH_BOUNDS = 5,
VK_DYNAMIC_STATE_STENCIL_COMPARE_MASK = 6,
VK_DYNAMIC_STATE_STENCIL_WRITE_MASK = 7,
VK_DYNAMIC_STATE_STENCIL_REFERENCE = 8,
} VkDynamicState;-
VK_DYNAMIC_STATE_VIEWPORTspecifies that thepViewportsstate in VkPipelineViewportStateCreateInfo will be ignored and must be set dynamically with vkCmdSetViewport before any drawing commands. The number of viewports used by a pipeline is still specified by theviewportCountmember of VkPipelineViewportStateCreateInfo. -
VK_DYNAMIC_STATE_SCISSORspecifies that thepScissorsstate in VkPipelineViewportStateCreateInfo will be ignored and must be set dynamically with vkCmdSetScissor before any drawing commands. The number of scissor rectangles used by a pipeline is still specified by thescissorCountmember of VkPipelineViewportStateCreateInfo. -
VK_DYNAMIC_STATE_LINE_WIDTHspecifies that thelineWidthstate in VkPipelineRasterizationStateCreateInfo will be ignored and must be set dynamically with vkCmdSetLineWidth before any drawing commands that generate line primitives for the rasterizer. -
VK_DYNAMIC_STATE_DEPTH_BIASspecifies that thedepthBiasConstantFactor,depthBiasClampanddepthBiasSlopeFactorstates in VkPipelineRasterizationStateCreateInfo will be ignored and must be set dynamically with vkCmdSetDepthBias before any draws are performed with depth bias enabled. -
VK_DYNAMIC_STATE_BLEND_CONSTANTSspecifies that theblendConstantsstate in VkPipelineColorBlendStateCreateInfo will be ignored and must be set dynamically with vkCmdSetBlendConstants before any draws are performed with a pipeline state withVkPipelineColorBlendAttachmentStatememberblendEnableset toVK_TRUEand any of the blend functions using a constant blend color. -
VK_DYNAMIC_STATE_DEPTH_BOUNDSspecifies that theminDepthBoundsandmaxDepthBoundsstates of VkPipelineDepthStencilStateCreateInfo will be ignored and must be set dynamically with vkCmdSetDepthBounds before any draws are performed with a pipeline state with VkPipelineDepthStencilStateCreateInfo memberdepthBoundsTestEnableset toVK_TRUE. -
VK_DYNAMIC_STATE_STENCIL_COMPARE_MASKspecifies that thecompareMaskstate in VkPipelineDepthStencilStateCreateInfo for bothfrontandbackwill be ignored and must be set dynamically with vkCmdSetStencilCompareMask before any draws are performed with a pipeline state with VkPipelineDepthStencilStateCreateInfo memberstencilTestEnableset toVK_TRUE -
VK_DYNAMIC_STATE_STENCIL_WRITE_MASKspecifies that thewriteMaskstate in VkPipelineDepthStencilStateCreateInfo for bothfrontandbackwill be ignored and must be set dynamically with vkCmdSetStencilWriteMask before any draws are performed with a pipeline state with VkPipelineDepthStencilStateCreateInfo memberstencilTestEnableset toVK_TRUE -
VK_DYNAMIC_STATE_STENCIL_REFERENCEspecifies that thereferencestate in VkPipelineDepthStencilStateCreateInfo for bothfrontandbackwill be ignored and must be set dynamically with vkCmdSetStencilReference before any draws are performed with a pipeline state with VkPipelineDepthStencilStateCreateInfo memberstencilTestEnableset toVK_TRUE
10.3.1. Valid Combinations of Stages for Graphics Pipelines
If tessellation shader stages are omitted, the tessellation shading and fixed-function stages of the pipeline are skipped.
If a geometry shader is omitted, the geometry shading stage is skipped.
If a fragment shader is omitted, fragment color outputs have undefined values, and the fragment depth value is determined by Fragment Operations state. This can be useful for depth-only rendering.
Presence of a shader stage in a pipeline is indicated by including a valid
VkPipelineShaderStageCreateInfo with module and pName
selecting an entry point from a shader module, where that entry point is
valid for the stage specified by stage.
Presence of some of the fixed-function stages in the pipeline is implicitly derived from enabled shaders and provided state. For example, the fixed-function tessellator is always present when the pipeline has valid Tessellation Control and Tessellation Evaluation shaders.
-
Depth/stencil-only rendering in a subpass with no color attachments
-
Active Pipeline Shader Stages
-
Vertex Shader
-
-
Required: Fixed-Function Pipeline Stages
-
-
Color-only rendering in a subpass with no depth/stencil attachment
-
Active Pipeline Shader Stages
-
Vertex Shader
-
Fragment Shader
-
-
Required: Fixed-Function Pipeline Stages
-
-
Rendering pipeline with tessellation and geometry shaders
-
Active Pipeline Shader Stages
-
Vertex Shader
-
Tessellation Control Shader
-
Tessellation Evaluation Shader
-
Geometry Shader
-
Fragment Shader
-
-
Required: Fixed-Function Pipeline Stages
-
10.4. Pipeline Destruction
To destroy a pipeline, call:
// Provided by VK_VERSION_1_0
void vkDestroyPipeline(
VkDevice device,
VkPipeline pipeline,
const VkAllocationCallbacks* pAllocator);-
deviceis the logical device that destroys the pipeline. -
pipelineis the handle of the pipeline to destroy. -
pAllocatorcontrols host memory allocation as described in the Memory Allocation chapter.
10.5. Pipeline Derivatives
A pipeline derivative is a child pipeline created from a parent pipeline, where the child and parent are expected to have much commonality.
The goal of derivative pipelines is that they be cheaper to create using the parent as a starting point, and that it be more efficient (on either host or device) to switch/bind between children of the same parent.
A derivative pipeline is created by setting the
VK_PIPELINE_CREATE_DERIVATIVE_BIT flag in the
Vk*PipelineCreateInfo structure.
If this is set, then exactly one of basePipelineHandle or
basePipelineIndex members of the structure must have a valid
handle/index, and specifies the parent pipeline.
If basePipelineHandle is used, the parent pipeline must have already
been created.
If basePipelineIndex is used, then the parent is being created in the
same command.
VK_NULL_HANDLE acts as the invalid handle for
basePipelineHandle, and -1 is the invalid index for
basePipelineIndex.
If basePipelineIndex is used, the base pipeline must appear earlier
in the array.
The base pipeline must have been created with the
VK_PIPELINE_CREATE_ALLOW_DERIVATIVES_BIT flag set.
10.6. Pipeline Cache
Pipeline cache objects allow the result of pipeline construction to be reused between pipelines and between runs of an application. Reuse between pipelines is achieved by passing the same pipeline cache object when creating multiple related pipelines. Reuse across runs of an application is achieved by retrieving pipeline cache contents in one run of an application, saving the contents, and using them to preinitialize a pipeline cache on a subsequent run. The contents of the pipeline cache objects are managed by the implementation. Applications can manage the host memory consumed by a pipeline cache object and control the amount of data retrieved from a pipeline cache object.
Pipeline cache objects are represented by VkPipelineCache handles:
// Provided by VK_VERSION_1_0
VK_DEFINE_NON_DISPATCHABLE_HANDLE(VkPipelineCache)10.6.1. Creating a Pipeline Cache
To create pipeline cache objects, call:
// Provided by VK_VERSION_1_0
VkResult vkCreatePipelineCache(
VkDevice device,
const VkPipelineCacheCreateInfo* pCreateInfo,
const VkAllocationCallbacks* pAllocator,
VkPipelineCache* pPipelineCache);-
deviceis the logical device that creates the pipeline cache object. -
pCreateInfois a pointer to a VkPipelineCacheCreateInfo structure containing initial parameters for the pipeline cache object. -
pAllocatorcontrols host memory allocation as described in the Memory Allocation chapter. -
pPipelineCacheis a pointer to a VkPipelineCache handle in which the resulting pipeline cache object is returned.
|
Note
Applications can track and manage the total host memory size of a pipeline
cache object using the |
Once created, a pipeline cache can be passed to the vkCreateGraphicsPipelines and vkCreateComputePipelines commands. If the pipeline cache passed into these commands is not VK_NULL_HANDLE, the implementation will query it for possible reuse opportunities and update it with new content. The use of the pipeline cache object in these commands is internally synchronized, and the same pipeline cache object can be used in multiple threads simultaneously.
|
Note
Implementations should make every effort to limit any critical sections to
the actual accesses to the cache, which is expected to be significantly
shorter than the duration of the |
The VkPipelineCacheCreateInfo structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkPipelineCacheCreateInfo {
VkStructureType sType;
const void* pNext;
VkPipelineCacheCreateFlags flags;
size_t initialDataSize;
const void* pInitialData;
} VkPipelineCacheCreateInfo;-
sTypeis a VkStructureType value identifying this structure. -
pNextisNULLor a pointer to a structure extending this structure. -
flagsis reserved for future use. -
initialDataSizeis the number of bytes inpInitialData. IfinitialDataSizeis zero, the pipeline cache will initially be empty. -
pInitialDatais a pointer to previously retrieved pipeline cache data. If the pipeline cache data is incompatible (as defined below) with the device, the pipeline cache will be initially empty. IfinitialDataSizeis zero,pInitialDatais ignored.
// Provided by VK_VERSION_1_0
typedef VkFlags VkPipelineCacheCreateFlags;VkPipelineCacheCreateFlags is a bitmask type for setting a mask, but
is currently reserved for future use.
10.6.2. Merging Pipeline Caches
Pipeline cache objects can be merged using the command:
// Provided by VK_VERSION_1_0
VkResult vkMergePipelineCaches(
VkDevice device,
VkPipelineCache dstCache,
uint32_t srcCacheCount,
const VkPipelineCache* pSrcCaches);-
deviceis the logical device that owns the pipeline cache objects. -
dstCacheis the handle of the pipeline cache to merge results into. -
srcCacheCountis the length of thepSrcCachesarray. -
pSrcCachesis a pointer to an array of pipeline cache handles, which will be merged intodstCache. The previous contents ofdstCacheare included after the merge.
|
Note
The details of the merge operation are implementation-dependent, but implementations should merge the contents of the specified pipelines and prune duplicate entries. |
10.6.3. Retrieving Pipeline Cache Data
Data can be retrieved from a pipeline cache object using the command:
// Provided by VK_VERSION_1_0
VkResult vkGetPipelineCacheData(
VkDevice device,
VkPipelineCache pipelineCache,
size_t* pDataSize,
void* pData);-
deviceis the logical device that owns the pipeline cache. -
pipelineCacheis the pipeline cache to retrieve data from. -
pDataSizeis a pointer to asize_tvalue related to the amount of data in the pipeline cache, as described below. -
pDatais eitherNULLor a pointer to a buffer.
If pData is NULL, then the maximum size of the data that can be
retrieved from the pipeline cache, in bytes, is returned in pDataSize.
Otherwise, pDataSize must point to a variable set by the user to the
size of the buffer, in bytes, pointed to by pData, and on return the
variable is overwritten with the amount of data actually written to
pData.
If pDataSize is less than the maximum size that can be retrieved by
the pipeline cache, at most pDataSize bytes will be written to
pData, and VK_INCOMPLETE will be returned instead of
VK_SUCCESS, to indicate that not all of the pipeline cache was
returned.
Any data written to pData is valid and can be provided as the
pInitialData member of the VkPipelineCacheCreateInfo structure
passed to vkCreatePipelineCache.
Two calls to vkGetPipelineCacheData with the same parameters must
retrieve the same data unless a command that modifies the contents of the
cache is called between them.
The initial bytes written to pData must be a header as described in
the Pipeline Cache Header section.
If pDataSize is less than what is necessary to store this header,
nothing will be written to pData and zero will be written to
pDataSize.
10.6.4. Pipeline Cache Header
Applications can store the data retrieved from the pipeline cache, and use these data, possibly in a future run of the application, to populate new pipeline cache objects. The results of pipeline compiles, however, may depend on the vendor ID, device ID, driver version, and other details of the device. To enable applications to detect when previously retrieved data is incompatible with the device, the pipeline cache data must begin with a valid pipeline cache header.
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Note
Structures described in this section are not part of the Vulkan API and are only used to describe the representation of data elements in pipeline cache data. Accordingly, the valid usage clauses defined for structures defined in this section do not define valid usage conditions for APIs accepting pipeline cache data as input, as providing invalid pipeline cache data as input to any Vulkan API commands will result in the provided pipeline cache data being ignored. |
Version one of the pipeline cache header is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkPipelineCacheHeaderVersionOne {
uint32_t headerSize;
VkPipelineCacheHeaderVersion headerVersion;
uint32_t vendorID;
uint32_t deviceID;
uint8_t pipelineCacheUUID[VK_UUID_SIZE];
} VkPipelineCacheHeaderVersionOne;-
headerSizeis the length in bytes of the pipeline cache header. -
headerVersionis a VkPipelineCacheHeaderVersion value specifying the version of the header. A consumer of the pipeline cache should use the cache version to interpret the remainder of the cache header. -
vendorIDis theVkPhysicalDeviceProperties::vendorIDof the implementation. -
deviceIDis theVkPhysicalDeviceProperties::deviceIDof the implementation. -
pipelineCacheUUIDis theVkPhysicalDeviceProperties::pipelineCacheUUIDof the implementation.
Unlike most structures declared by the Vulkan API, all fields of this structure are written with the least significant byte first, regardless of host byte-order.
The C language specification does not define the packing of structure members. This layout assumes tight structure member packing, with members laid out in the order listed in the structure, and the intended size of the structure is 32 bytes. If a compiler produces code that diverges from that pattern, applications must employ another method to set values at the correct offsets.
Possible values of the headerVersion value of the pipeline cache
header are:
// Provided by VK_VERSION_1_0
typedef enum VkPipelineCacheHeaderVersion {
VK_PIPELINE_CACHE_HEADER_VERSION_ONE = 1,
} VkPipelineCacheHeaderVersion;-
VK_PIPELINE_CACHE_HEADER_VERSION_ONEspecifies version one of the pipeline cache, described by VkPipelineCacheHeaderVersionOne.
10.6.5. Destroying a Pipeline Cache
To destroy a pipeline cache, call:
// Provided by VK_VERSION_1_0
void vkDestroyPipelineCache(
VkDevice device,
VkPipelineCache pipelineCache,
const VkAllocationCallbacks* pAllocator);-
deviceis the logical device that destroys the pipeline cache object. -
pipelineCacheis the handle of the pipeline cache to destroy. -
pAllocatorcontrols host memory allocation as described in the Memory Allocation chapter.
10.7. Specialization Constants
Specialization constants are a mechanism whereby constants in a SPIR-V
module can have their constant value specified at the time the
VkPipeline is created.
This allows a SPIR-V module to have constants that can be modified while
executing an application that uses the Vulkan API.
|
Note
Specialization constants are useful to allow a compute shader to have its local workgroup size changed at runtime by the user, for example. |
Each VkPipelineShaderStageCreateInfo structure contains a
pSpecializationInfo member, which can be NULL to indicate no
specialization constants, or point to a VkSpecializationInfo
structure.
The VkSpecializationInfo structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkSpecializationInfo {
uint32_t mapEntryCount;
const VkSpecializationMapEntry* pMapEntries;
size_t dataSize;
const void* pData;
} VkSpecializationInfo;-
mapEntryCountis the number of entries in thepMapEntriesarray. -
pMapEntriesis a pointer to an array ofVkSpecializationMapEntrystructures, which map constant IDs to offsets inpData. -
dataSizeis the byte size of thepDatabuffer. -
pDatacontains the actual constant values to specialize with.
The VkSpecializationMapEntry structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkSpecializationMapEntry {
uint32_t constantID;
uint32_t offset;
size_t size;
} VkSpecializationMapEntry;-
constantIDis the ID of the specialization constant in SPIR-V. -
offsetis the byte offset of the specialization constant value within the supplied data buffer. -
sizeis the byte size of the specialization constant value within the supplied data buffer.
If a constantID value is not a specialization constant ID used in the
shader, that map entry does not affect the behavior of the pipeline.
In human readable SPIR-V:
OpDecorate %x SpecId 13 ; decorate .x component of WorkgroupSize with ID 13
OpDecorate %y SpecId 42 ; decorate .y component of WorkgroupSize with ID 42
OpDecorate %z SpecId 3 ; decorate .z component of WorkgroupSize with ID 3
OpDecorate %wgsize BuiltIn WorkgroupSize ; decorate WorkgroupSize onto constant
%i32 = OpTypeInt 32 0 ; declare an unsigned 32-bit type
%uvec3 = OpTypeVector %i32 3 ; declare a 3 element vector type of unsigned 32-bit
%x = OpSpecConstant %i32 1 ; declare the .x component of WorkgroupSize
%y = OpSpecConstant %i32 1 ; declare the .y component of WorkgroupSize
%z = OpSpecConstant %i32 1 ; declare the .z component of WorkgroupSize
%wgsize = OpSpecConstantComposite %uvec3 %x %y %z ; declare WorkgroupSizeFrom the above we have three specialization constants, one for each of the x, y & z elements of the WorkgroupSize vector.
Now to specialize the above via the specialization constants mechanism:
const VkSpecializationMapEntry entries[] =
{
{
.constantID = 13,
.offset = 0 * sizeof(uint32_t),
.size = sizeof(uint32_t)
},
{
.constantID = 42,
.offset = 1 * sizeof(uint32_t),
.size = sizeof(uint32_t)
},
{
.constantID = 3,
.offset = 2 * sizeof(uint32_t),
.size = sizeof(uint32_t)
}
};
const uint32_t data[] = { 16, 8, 4 }; // our workgroup size is 16x8x4
const VkSpecializationInfo info =
{
.mapEntryCount = 3,
.pMapEntries = entries,
.dataSize = 3 * sizeof(uint32_t),
.pData = data,
};Then when calling vkCreateComputePipelines, and passing the
VkSpecializationInfo we defined as the pSpecializationInfo
parameter of VkPipelineShaderStageCreateInfo, we will create a compute
pipeline with the runtime specified local workgroup size.
Another example would be that an application has a SPIR-V module that has some platform-dependent constants they wish to use.
In human readable SPIR-V:
OpDecorate %1 SpecId 0 ; decorate our signed 32-bit integer constant
OpDecorate %2 SpecId 12 ; decorate our 32-bit floating-point constant
%i32 = OpTypeInt 32 1 ; declare a signed 32-bit type
%float = OpTypeFloat 32 ; declare a 32-bit floating-point type
%1 = OpSpecConstant %i32 -1 ; some signed 32-bit integer constant
%2 = OpSpecConstant %float 0.5 ; some 32-bit floating-point constantFrom the above we have two specialization constants, one is a signed 32-bit integer and the second is a 32-bit floating-point value.
Now to specialize the above via the specialization constants mechanism:
struct SpecializationData {
int32_t data0;
float data1;
};
const VkSpecializationMapEntry entries[] =
{
{
.constantID = 0,
.offset = offsetof(SpecializationData, data0),
.size = sizeof(SpecializationData::data0)
},
{
.constantID = 12,
.offset = offsetof(SpecializationData, data1),
.size = sizeof(SpecializationData::data1)
}
};
SpecializationData data;
data.data0 = -42; // set the data for the 32-bit integer
data.data1 = 42.0f; // set the data for the 32-bit floating-point
const VkSpecializationInfo info =
{
.mapEntryCount = 2,
.pMapEntries = entries,
.dataSize = sizeof(data),
.pdata = &data,
};It is legal for a SPIR-V module with specializations to be compiled into a pipeline where no specialization information was provided. SPIR-V specialization constants contain default values such that if a specialization is not provided, the default value will be used. In the examples above, it would be valid for an application to only specialize some of the specialization constants within the SPIR-V module, and let the other constants use their default values encoded within the OpSpecConstant declarations.
10.8. Pipeline Binding
Once a pipeline has been created, it can be bound to the command buffer using the command:
// Provided by VK_VERSION_1_0
void vkCmdBindPipeline(
VkCommandBuffer commandBuffer,
VkPipelineBindPoint pipelineBindPoint,
VkPipeline pipeline);-
commandBufferis the command buffer that the pipeline will be bound to. -
pipelineBindPointis a VkPipelineBindPoint value specifying to which bind point the pipeline is bound. Binding one does not disturb the others. -
pipelineis the pipeline to be bound.
Once bound, a pipeline binding affects subsequent commands that interact with the given pipeline type in the command buffer until a different pipeline of the same type is bound to the bind point. Commands that do not interact with the given pipeline type must not be affected by the pipeline state.
Possible values of vkCmdBindPipeline::pipelineBindPoint,
specifying the bind point of a pipeline object, are:
// Provided by VK_VERSION_1_0
typedef enum VkPipelineBindPoint {
VK_PIPELINE_BIND_POINT_GRAPHICS = 0,
VK_PIPELINE_BIND_POINT_COMPUTE = 1,
} VkPipelineBindPoint;-
VK_PIPELINE_BIND_POINT_COMPUTEspecifies binding as a compute pipeline. -
VK_PIPELINE_BIND_POINT_GRAPHICSspecifies binding as a graphics pipeline.
10.9. Dynamic State
When a pipeline object is bound, any pipeline object state that is not specified as dynamic is applied to the command buffer state. Pipeline object state that is specified as dynamic is not applied to the command buffer state at this time. Instead, dynamic state can be modified at any time and persists for the lifetime of the command buffer, or until modified by another dynamic state setting command, or made invalid by another pipeline bind with that state specified as static.
When a pipeline object is bound, the following applies to each state parameter:
-
If the state is not specified as dynamic in the new pipeline object, then that command buffer state is overwritten by the state in the new pipeline object. Before any draw or dispatch call with this pipeline there must not have been any calls to any of the corresponding dynamic state setting commands after this pipeline was bound.
-
If the state is specified as dynamic in the new pipeline object, then that command buffer state is not disturbed. Before any draw or dispatch call with this pipeline there must have been at least one call to each of the corresponding dynamic state setting commands. The state-setting commands must be recorded after command buffer recording was begun, or after the last command binding a pipeline object with that state specified as static, whichever was the latter.
-
If the state is not included (corresponding pointer in VkGraphicsPipelineCreateInfo was
NULLor was ignored) in the new pipeline object, then that command buffer state is not disturbed.
Dynamic state that does not affect the result of operations can be left undefined.
|
Note
For example, if blending is disabled by the pipeline object state then the dynamic color blend constants do not need to be specified in the command buffer, even if this state is specified as dynamic in the pipeline object. |
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Note
Applications running on Vulkan implementations advertising an
VkPhysicalDeviceDriverProperties:: |