## C Specification

To dispatch ray tracing use:

// Provided by VK_NV_ray_tracing
void vkCmdTraceRaysNV(
VkCommandBuffer                             commandBuffer,
uint32_t                                    width,
uint32_t                                    height,
uint32_t                                    depth);

## Parameters

• commandBuffer is the command buffer into which the command will be recorded.

• raygenShaderBindingTableBuffer is the buffer object that holds the shader binding table data for the ray generation shader stage.

• raygenShaderBindingOffset is the offset in bytes (relative to raygenShaderBindingTableBuffer) of the ray generation shader being used for the trace.

• missShaderBindingTableBuffer is the buffer object that holds the shader binding table data for the miss shader stage.

• missShaderBindingOffset is the offset in bytes (relative to missShaderBindingTableBuffer) of the miss shader being used for the trace.

• missShaderBindingStride is the size in bytes of each shader binding table record in missShaderBindingTableBuffer.

• hitShaderBindingTableBuffer is the buffer object that holds the shader binding table data for the hit shader stages.

• hitShaderBindingOffset is the offset in bytes (relative to hitShaderBindingTableBuffer) of the hit shader group being used for the trace.

• hitShaderBindingStride is the size in bytes of each shader binding table record in hitShaderBindingTableBuffer.

• callableShaderBindingTableBuffer is the buffer object that holds the shader binding table data for the callable shader stage.

• callableShaderBindingOffset is the offset in bytes (relative to callableShaderBindingTableBuffer) of the callable shader being used for the trace.

• callableShaderBindingStride is the size in bytes of each shader binding table record in callableShaderBindingTableBuffer.

• width is the width of the ray trace query dimensions.

• height is height of the ray trace query dimensions.

• depth is depth of the ray trace query dimensions.

## Description

When the command is executed, a ray generation group of width × height × depth rays is assembled.

Valid Usage
• If a VkImageView is sampled with VK_FILTER_LINEAR as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT

• If a VkImageView is accessed using atomic operations as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_STORAGE_IMAGE_ATOMIC_BIT

• If a VkImageView is sampled with VK_FILTER_CUBIC_EXT as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_CUBIC_BIT_EXT

• Any VkImageView being sampled with VK_FILTER_CUBIC_EXT as a result of this command must have a VkImageViewType and format that supports cubic filtering, as specified by VkFilterCubicImageViewImageFormatPropertiesEXT::filterCubic returned by vkGetPhysicalDeviceImageFormatProperties2

• Any VkImageView being sampled with VK_FILTER_CUBIC_EXT with a reduction mode of either VK_SAMPLER_REDUCTION_MODE_MIN or VK_SAMPLER_REDUCTION_MODE_MAX as a result of this command must have a VkImageViewType and format that supports cubic filtering together with minmax filtering, as specified by VkFilterCubicImageViewImageFormatPropertiesEXT::filterCubicMinmax returned by vkGetPhysicalDeviceImageFormatProperties2

• Any VkImage created with a VkImageCreateInfo::flags containing VK_IMAGE_CREATE_CORNER_SAMPLED_BIT_NV sampled as a result of this command must only be sampled using a VkSamplerAddressMode of VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE

• For each set n that is statically used by the VkPipeline bound to the pipeline bind point used by this command, a descriptor set must have been bound to n at the same pipeline bind point, with a VkPipelineLayout that is compatible for set n, with the VkPipelineLayout used to create the current VkPipeline, as described in [descriptorsets-compatibility]

• For each push constant that is statically used by the VkPipeline bound to the pipeline bind point used by this command, a push constant value must have been set for the same pipeline bind point, with a VkPipelineLayout that is compatible for push constants, with the VkPipelineLayout used to create the current VkPipeline, as described in [descriptorsets-compatibility]

• Descriptors in each bound descriptor set, specified via vkCmdBindDescriptorSets, must be valid if they are statically used by the VkPipeline bound to the pipeline bind point used by this command

• A valid pipeline must be bound to the pipeline bind point used by this command

• If the VkPipeline object bound to the pipeline bind point used by this command requires any dynamic state, that state must have been set for commandBuffer, and done so after any previously bound pipeline with the corresponding state not specified as dynamic

• There must not have been any calls to dynamic state setting commands for any state not specified as dynamic in the VkPipeline object bound to the pipeline bind point used by this command, since that pipeline was bound

• If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used to sample from any VkImage with a VkImageView of the type VK_IMAGE_VIEW_TYPE_3D, VK_IMAGE_VIEW_TYPE_CUBE, VK_IMAGE_VIEW_TYPE_1D_ARRAY, VK_IMAGE_VIEW_TYPE_2D_ARRAY or VK_IMAGE_VIEW_TYPE_CUBE_ARRAY, in any shader stage

• If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions with ImplicitLod, Dref or Proj in their name, in any shader stage

• If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions that includes a LOD bias or any offset values, in any shader stage

• If the robust buffer access feature is not enabled, and if the VkPipeline object bound to the pipeline bind point used by this command accesses a uniform buffer, it must not access values outside of the range of the buffer as specified in the descriptor set bound to the same pipeline bind point

• If the robust buffer access feature is not enabled, and if the VkPipeline object bound to the pipeline bind point used by this command accesses a storage buffer, it must not access values outside of the range of the buffer as specified in the descriptor set bound to the same pipeline bind point

• If commandBuffer is an unprotected command buffer, any resource accessed by the VkPipeline object bound to the pipeline bind point used by this command must not be a protected resource

• If a VkImageView is accessed using OpImageWrite as a result of this command, then the Type of the Texel operand of that instruction must have at least as many components as the image view’s format.

• Any shader group handle referenced by this call must have been queried from the currently bound ray tracing shader pipeline

• This command must not cause a shader call instruction to be executed from a shader invocation with a recursion depth greater than the value of maxRecursionDepth used to create the bound ray tracing pipeline

• If commandBuffer is a protected command buffer, any resource written to by the VkPipeline object bound to the pipeline bind point used by this command must not be an unprotected resource

• If commandBuffer is a protected command buffer, pipeline stages other than the framebuffer-space and compute stages in the VkPipeline object bound to the pipeline bind point must not write to any resource

• If raygenShaderBindingTableBuffer is non-sparse then it must be bound completely and contiguously to a single VkDeviceMemory object

• raygenShaderBindingOffset must be less than the size of raygenShaderBindingTableBuffer

• raygenShaderBindingOffset must be a multiple of VkPhysicalDeviceRayTracingPropertiesNV::shaderGroupBaseAlignment

• If missShaderBindingTableBuffer is non-sparse then it must be bound completely and contiguously to a single VkDeviceMemory object

• missShaderBindingOffset must be less than the size of missShaderBindingTableBuffer

• missShaderBindingOffset must be a multiple of VkPhysicalDeviceRayTracingPropertiesNV::shaderGroupBaseAlignment

• If hitShaderBindingTableBuffer is non-sparse then it must be bound completely and contiguously to a single VkDeviceMemory object

• hitShaderBindingOffset must be less than the size of hitShaderBindingTableBuffer

• hitShaderBindingOffset must be a multiple of VkPhysicalDeviceRayTracingPropertiesNV::shaderGroupBaseAlignment

• If callableShaderBindingTableBuffer is non-sparse then it must be bound completely and contiguously to a single VkDeviceMemory object

• callableShaderBindingOffset must be less than the size of callableShaderBindingTableBuffer

• callableShaderBindingOffset must be a multiple of VkPhysicalDeviceRayTracingPropertiesNV::shaderGroupBaseAlignment

• missShaderBindingStride must be a multiple of VkPhysicalDeviceRayTracingPropertiesNV::shaderGroupHandleSize

• hitShaderBindingStride must be a multiple of VkPhysicalDeviceRayTracingPropertiesNV::shaderGroupHandleSize

• callableShaderBindingStride must be a multiple of VkPhysicalDeviceRayTracingPropertiesNV::shaderGroupHandleSize

• missShaderBindingStride must be less than or equal to VkPhysicalDeviceRayTracingPropertiesNV::maxShaderGroupStride

• hitShaderBindingStride must be less than or equal to VkPhysicalDeviceRayTracingPropertiesNV::maxShaderGroupStride

• callableShaderBindingStride must be less than or equal to VkPhysicalDeviceRayTracingPropertiesNV::maxShaderGroupStride

• width must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[0]

• height must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[1]

• depth must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[2]

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

• raygenShaderBindingTableBuffer must be a valid VkBuffer handle

• If missShaderBindingTableBuffer is not VK_NULL_HANDLE, missShaderBindingTableBuffer must be a valid VkBuffer handle

• If hitShaderBindingTableBuffer is not VK_NULL_HANDLE, hitShaderBindingTableBuffer must be a valid VkBuffer handle

• If callableShaderBindingTableBuffer is not VK_NULL_HANDLE, callableShaderBindingTableBuffer must be a valid VkBuffer handle

• commandBuffer must be in the recording state

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

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

• Each of callableShaderBindingTableBuffer, commandBuffer, hitShaderBindingTableBuffer, missShaderBindingTableBuffer, and raygenShaderBindingTableBuffer that are valid handles of non-ignored parameters must have been created, allocated, or retrieved from the same VkDevice

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
Secondary

Outside

Compute

VkBuffer, VkCommandBuffer, VkDeviceSize