CmdCreateBLAS()

void Spices::VulkanRayTracing::CmdCreateBLAS ( VkCommandBuffer cmdBuf, const std::vector< uint32_t > & indices, std::vector< BuildAccelerationStructure > & buildAs, VkDeviceAddress scratchAddress, std::shared_ptr< VulkanQueryPool > queryPool ) const

private

Creating the bottom level acceleration structure for all indices of buildAs vector. The array of BuildAccelerationStructure was created in buildBlas and the vector of indices limits the number of BLAS to create at once. This limits the amount of memory needed when compacting the BLAS.

Parameters

[in]	cmdBuf	VkCommandBuffer.
[in]	indices	BLAS indices.
[in]	buildAs	BuildAccelerationStructure.
[in]	scratchAddress	.
[in]	queryPool	Query AccelerationStructure data.

Querying the compaction size.

creating all the BLAS defined by the index chunk.

Actual allocation of buffer and acceleration structure.

BuildInfo #2 part.

Building the bottom - level - acceleration - structure.

Since the scratch buffer is reused across builds, we need a barrier to ensure one build is finished before starting the next one.

Add the size query only if needed.

Add a query to find the 'real' amount of memory needed, use for compaction.

Querying the compaction size.

creating all the BLAS defined by the index chunk.

Actual allocation of buffer and acceleration structure.

BuildInfo #2 part.

Building the bottom - level - acceleration - structure.

Since the scratch buffer is reused across builds, we need a barrier to ensure one build is finished before starting the next one.

Add the size query only if needed.

Add a query to find the 'real' amount of memory needed, use for compaction.

Definition at line 469 of file VulkanRayTracing.cpp.

    {
        SPICES_PROFILE_ZONE;
 
        if (queryPool)  
        {
            queryPool->Reset(cmdBuf);
        }
 
        uint32_t queryCnt{ 0 };
 
        for (const auto& idx : indices)
        {
            VkAccelerationStructureCreateInfoKHR      createInfo{};
            createInfo.sType                        = VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_CREATE_INFO_KHR;
            createInfo.type                         = VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR;
            createInfo.size                         = buildAs[idx].sizeInfo.accelerationStructureSize;  // Will be used to allocate memory.
 
            *buildAs[idx].as = CreateAcceleration(createInfo);
 
            buildAs[idx].buildInfo.dstAccelerationStructure  = buildAs[idx].as->accel->Get();          // Setting where the build lands
            buildAs[idx].buildInfo.scratchData.deviceAddress = scratchAddress;                         // All build are using the same scratch buffer
 
            m_VulkanState.m_VkFunc.vkCmdBuildAccelerationStructuresKHR(cmdBuf, 1, &buildAs[idx].buildInfo, &buildAs[idx].rangeInfo);
 
            VkMemoryBarrier barrier{};
            barrier.sType                                  = VK_STRUCTURE_TYPE_MEMORY_BARRIER;
            barrier.srcAccessMask                          = VK_ACCESS_ACCELERATION_STRUCTURE_WRITE_BIT_KHR;
            barrier.dstAccessMask                          = VK_ACCESS_ACCELERATION_STRUCTURE_READ_BIT_KHR;
 
            vkCmdPipelineBarrier(
                cmdBuf, 
                VK_PIPELINE_STAGE_ACCELERATION_STRUCTURE_BUILD_BIT_KHR,
                VK_PIPELINE_STAGE_ACCELERATION_STRUCTURE_BUILD_BIT_KHR, 
                0, 
                1, 
                &barrier, 
                0, 
                nullptr, 
                0, 
                nullptr
            );
 
            if (queryPool)
            {
                m_VulkanState.m_VkFunc.vkCmdWriteAccelerationStructuresPropertiesKHR(
                    cmdBuf, 
                    1,
                    &buildAs[idx].buildInfo.dstAccelerationStructure,
                    VK_QUERY_TYPE_ACCELERATION_STRUCTURE_COMPACTED_SIZE_KHR, 
                    queryPool->Get(),
                    queryCnt++
                );
            }
        }
    }