Package org.lwjgl.vulkan

Class HUAWEISubpassShading

java.lang.Object
org.lwjgl.vulkan.HUAWEISubpassShading
public class HUAWEISubpassShading extends Object
This extension allows applications to execute a subpass shading pipeline in a subpass of a render pass in order to save memory bandwidth for algorithms like tile-based deferred rendering and forward plus. A subpass shading pipeline is a pipeline with the compute pipeline ability, allowed to read values from input attachments, and only allowed to be dispatched inside a stand-alone subpass. Its work dimension is defined by the render pass’s render area size. Its workgroup size (width, height) shall be a power-of-two number in width or height, with minimum value from 8, and maximum value shall be decided from the render pass attachments and sample counts but depends on implementation.

The GlobalInvocationId.xy of a subpass shading pipeline is equal to the FragCoord.xy of a graphic pipeline in the same render pass subtracted the offset of the VkRenderPassBeginInfo::renderArea. GlobalInvocationId.z is mapped to the Layer if VK_EXT_shader_viewport_index_layer is supported. The GlobalInvocationId.xy is equal to the index of the local workgroup multiplied by the size of the local workgroup plus the LocalInvocationId and the offset of the VkRenderPassBeginInfo::renderArea.

This extension allows a subpass’s pipeline bind point to be PIPELINE_BIND_POINT_SUBPASS_SHADING_HUAWEI.

Sample Code

Example of subpass shading in a GLSL shader


 #extension GL_HUAWEI_subpass_shading: enable
 #extension GL_KHR_shader_subgroup_arithmetic: enable
 
 layout(constant_id = 0) const uint tileWidth = 8;
 layout(constant_id = 1) const uint tileHeight = 8;
 layout(local_size_x_id = 0, local_size_y_id = 1, local_size_z = 1) in;
 layout(set=0, binding=0, input_attachment_index=0) uniform subpassInput depth;
 
 void main()
 {
   float d = subpassLoad(depth).x;
   float minD = subgroupMin(d);
   float maxD = subgroupMax(d);
 }

Example of subpass shading dispatching in a subpass


 vkCmdNextSubpass(commandBuffer, VK_SUBPASS_CONTENTS_INLINE);
 vkCmdBindPipeline(commandBuffer, VK_PIPELINE_BIND_POINT_SUBPASS_SHADING_HUAWEI, subpassShadingPipeline);
 vkCmdBindDescriptorSets(commandBuffer, VK_PIPELINE_BIND_POINT_SUBPASS_SHADING_HUAWEI, subpassShadingPipelineLayout,
   firstSet, descriptorSetCount, pDescriptorSets, dynamicOffsetCount, pDynamicOffsets);
 vkCmdSubpassShadingHUAWEI(commandBuffer)
 vkCmdEndRenderPass(commandBuffer);

Example of subpass shading render pass creation


 VkAttachmentDescription2 attachments[] = {
   {
     VK_STRUCTURE_TYPE_ATTACHMENT_DESCRIPTION_2, NULL,
     0, VK_FORMAT_R8G8B8A8_UNORM, VK_SAMPLE_COUNT_1_BIT,
     VK_ATTACHMENT_LOAD_OP_CLEAR, VK_ATTACHMENT_STORE_OP_DONT_CARE,
     VK_ATTACHMENT_LOAD_OP_DONT_CARE, VK_ATTACHMENT_LOAD_OP_DONT_CARE,
     VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL
   },
   {
     VK_STRUCTURE_TYPE_ATTACHMENT_DESCRIPTION_2, NULL,
     0, VK_FORMAT_R8G8B8A8_UNORM, VK_SAMPLE_COUNT_1_BIT,
     VK_ATTACHMENT_LOAD_OP_CLEAR, VK_ATTACHMENT_STORE_OP_DONT_CARE,
     VK_ATTACHMENT_LOAD_OP_DONT_CARE, VK_ATTACHMENT_LOAD_OP_DONT_CARE,
     VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL
   },
   {
     VK_STRUCTURE_TYPE_ATTACHMENT_DESCRIPTION_2, NULL,
     0, VK_FORMAT_R8G8B8A8_UNORM, VK_SAMPLE_COUNT_1_BIT,
     VK_ATTACHMENT_LOAD_OP_CLEAR, VK_ATTACHMENT_STORE_OP_DONT_CARE,
     VK_ATTACHMENT_LOAD_OP_DONT_CARE, VK_ATTACHMENT_LOAD_OP_DONT_CARE,
     VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL
   },
   {
     VK_STRUCTURE_TYPE_ATTACHMENT_DESCRIPTION_2, NULL,
     0, VK_FORMAT_D24_UNORM_S8_UINT, VK_SAMPLE_COUNT_1_BIT,
     VK_ATTACHMENT_LOAD_OP_CLEAR, VK_ATTACHMENT_STORE_OP_DONT_CARE,
     VK_ATTACHMENT_LOAD_OP_CLEAR, VK_ATTACHMENT_LOAD_OP_DONT_CARE,
     VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL
   },
   {
     VK_STRUCTURE_TYPE_ATTACHMENT_DESCRIPTION_2, NULL,
     0, VK_FORMAT_R8G8B8A8_UNORM, VK_SAMPLE_COUNT_1_BIT,
     VK_ATTACHMENT_LOAD_OP_CLEAR, VK_ATTACHMENT_STORE_OP_STORE,
     VK_ATTACHMENT_LOAD_OP_DONT_CARE, VK_ATTACHMENT_LOAD_OP_DONT_CARE,
     VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL
   }
 };
 
 VkAttachmentReference2 gBufferAttachmentReferences[] = {
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT },
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 1, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT },
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 2, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT }
 };
 VkAttachmentReference2 gBufferDepthStencilAttachmentReferences =
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 3, VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_DEPTH_BIT|VK_IMAGE_ASPECT_STENCIL_BIT };
 VkAttachmentReference2 depthInputAttachmentReferences[] = {
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 3, VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL, VK_IMAGE_ASPECT_DEPTH_BIT|VK_IMAGE_ASPECT_STENCIL_BIT };
 };
 VkAttachmentReference2 preserveAttachmentReferences[] = {
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT },
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 1, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT },
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 2, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT },
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 3, VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_DEPTH_BIT|VK_IMAGE_ASPECT_STENCIL_BIT }
 }; // G buffer including depth/stencil
 VkAttachmentReference2 colorAttachmentReferences[] = {
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 4, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT }
 };
 VkAttachmentReference2 resolveAttachmentReference =
   { VK_STRUCTURE_TYPE_ATTACHMENT_REFERENCE_2, NULL, 4, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT };
 
 VkSubpassDescription2 subpasses[] = {
   {
     VK_STRUCTURE_TYPE_SUBPASS_DESCRIPTION_2, NULL, 0, VK_PIPELINE_BIND_POINT_GRAPHICS, 0,
     0, NULL, // input
     sizeof(gBufferAttachmentReferences)/sizeof(gBufferAttachmentReferences[0]), gBufferAttachmentReferences, // color
     NULL, &gBufferDepthStencilAttachmentReferences, // resolve & DS
     0, NULL
   },
   {
     VK_STRUCTURE_TYPE_SUBPASS_DESCRIPTION_2, NULL, 0, VK_PIPELINE_BIND_POINT_SUBPASS_SHADING_HUAWEI , 0,
     sizeof(depthInputAttachmentReferences)/sizeof(depthInputAttachmentReferences[0]), depthInputAttachmentReferences, // input
     0, NULL, // color
     NULL, NULL, // resolve & DS
     sizeof(preserveAttachmentReferences)/sizeof(preserveAttachmentReferences[0]), preserveAttachmentReferences,
   },
   {
     VK_STRUCTURE_TYPE_SUBPASS_DESCRIPTION_2, NULL, 0, VK_PIPELINE_BIND_POINT_GRAPHICS, 0,
     sizeof(gBufferAttachmentReferences)/sizeof(gBufferAttachmentReferences[0]), gBufferAttachmentReferences, // input
     sizeof(colorAttachmentReferences)/sizeof(colorAttachmentReferences[0]), colorAttachmentReferences, // color
     &resolveAttachmentReference, &gBufferDepthStencilAttachmentReferences, // resolve & DS
     0, NULL
   },
 };
 
 VkMemoryBarrier2KHR fragmentToSubpassShading = {
   VK_STRUCTURE_TYPE_MEMORY_BARRIER_2_KHR, NULL,
   VK_PIPELINE_STAGE_2_FRAGMENT_SHADER_BIT_KHR, VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT|VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT,
   VK_PIPELINE_STAGE_2_SUBPASS_SHADER_BIT_HUAWEI, VK_ACCESS_INPUT_ATTACHMENT_READ_BIT
 };
 
 VkMemoryBarrier2KHR subpassShadingToFragment = {
   VK_STRUCTURE_TYPE_MEMORY_BARRIER_2_KHR, NULL,
   VK_PIPELINE_STAGE_2_SUBPASS_SHADER_BIT_HUAWEI, VK_ACCESS_SHADER_WRITE_BIT,
   VK_PIPELINE_STAGE_2_FRAGMENT_SHADER_BIT_KHR, VK_ACCESS_SHADER_READ_BIT
 };
 
 VkSubpassDependency2 dependencies[] = {
   {
     VK_STRUCTURE_TYPE_SUBPASS_DEPENDENCY_2, &fragmentToSubpassShading,
     0, 1,
     0, 0, 0, 0,
     0, 0
   },
   {
     VK_STRUCTURE_TYPE_SUBPASS_DEPENDENCY_2, &subpassShadingToFragment,
     1, 2,
     0, 0, 0, 0,
     0, 0
   },
 };
 
 VkRenderPassCreateInfo2 renderPassCreateInfo = {
   VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO_2, NULL, 0,
     sizeof(attachments)/sizeof(attachments[0]), attachments,
     sizeof(subpasses)/sizeof(subpasses[0]), subpasses,
     sizeof(dependencies)/sizeof(dependencies[0]), dependencies,
     0, NULL
 };
 VKRenderPass renderPass;
 vkCreateRenderPass2(device, &renderPassCreateInfo, NULL, &renderPass);

Example of subpass shading pipeline creation


 VkExtent2D maxWorkgroupSize;
 
 VkSpecializationMapEntry subpassShadingConstantMapEntries[] = {
   { 0, 0 * sizeof(uint32_t), sizeof(uint32_t) },
   { 1, 1 * sizeof(uint32_t), sizeof(uint32_t) }
 };
 
 VkSpecializationInfo subpassShadingConstants = {
   2, subpassShadingConstantMapEntries,
   sizeof(VkExtent2D), &maxWorkgroupSize
 };
 
 VkSubpassShadingPipelineCreateInfoHUAWEI subpassShadingPipelineCreateInfo {
   VK_STRUCTURE_TYPE_SUBPASSS_SHADING_PIPELINE_CREATE_INFO_HUAWEI, NULL,
   renderPass, 1
 };
 
 VkPipelineShaderStageCreateInfo subpassShadingPipelineStageCreateInfo {
   VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO, NULL,
   0, VK_SHADER_STAGE_SUBPASS_SHADING_BIT_HUAWEI,
   shaderModule, "main",
   &subpassShadingConstants
 };
 
 VkComputePipelineCreateInfo subpassShadingComputePipelineCreateInfo = {
   VK_STRUCTURE_TYPE_COMPUTE_PIPELINE_CREATE_INFO, &subpassShadingPipelineCreateInfo,
   0, &subpassShadingPipelineStageCreateInfo,
   pipelineLayout, basePipelineHandle, basePipelineIndex
 };
 
 VKPipeline pipeline;
 
 vkGetDeviceSubpassShadingMaxWorkgroupSizeHUAWEI(device, renderPass, &maxWorkgroupSize);
 vkCreateComputePipelines(device, pipelineCache, 1, &subpassShadingComputePipelineCreateInfo, NULL, &pipeline);
Name String
VK_HUAWEI_subpass_shading
Extension Type
Device extension
Registered Extension Number
370
Revision
3
Extension and Version Dependencies
VK_KHR_create_renderpass2 or Version 1.2 and VK_KHR_synchronization2 or Version 1.3
SPIR-V Dependencies
Contact
Other Extension Metadata
Last Modified Date
2021-06-01
Interactions and External Dependencies
Contributors
  • Hueilong Wang
  • Juntao Li, Huawei
  • Renmiao Lu, Huawei
  • Pan Gao, Huawei