UpdateBlas()

void Spices::VulkanRayTracing::UpdateBlas	(	uint32_t	blasIdx,
		const BlasInput &	blas,
		VkBuildAccelerationStructureFlagsKHR	flags ) const

Update part of BLAS.

Parameters

[in]	blasIdx	index of BLAS.
[in]	blas	specific BlasInput.
[in]	flags	VkBuildAccelerationStructureFlagsKHR.

Definition at line 155 of file VulkanRayTracing.cpp.

    {
        SPICES_PROFILE_ZONE;
 
        // Preparing all build information, acceleration is filled later
        VkAccelerationStructureBuildGeometryInfoKHR buildInfos{};
        buildInfos.sType                           = VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_BUILD_GEOMETRY_INFO_KHR;
        buildInfos.flags                           = flags;
        buildInfos.geometryCount                   = static_cast<uint32_t>(blas.asGeometry.size());
        buildInfos.pGeometries                     = blas.asGeometry.data();
        buildInfos.mode                            = VK_BUILD_ACCELERATION_STRUCTURE_MODE_UPDATE_KHR;  // UPDATE
        buildInfos.type                            = VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR;
        //buildInfos.srcAccelerationStructure        = m_blas[blasIdx].accel;  // UPDATE
        //buildInfos.dstAccelerationStructure        = m_blas[blasIdx].accel;
 
        // Find size to build on the device
        std::vector<uint32_t> maxPrimCount(blas.asBuildOffsetInfo.size());
 
        for (auto tt = 0; tt < blas.asBuildOffsetInfo.size(); tt++)
        {
            maxPrimCount[tt] = blas.asBuildOffsetInfo[tt].primitiveCount;  // Number of primitives/triangles
        }
 
        VkAccelerationStructureBuildSizesInfoKHR sizeInfo{};
        sizeInfo.sType = VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_BUILD_SIZES_INFO_KHR;
 
        m_VulkanState.m_VkFunc.vkGetAccelerationStructureBuildSizesKHR(
            m_VulkanState.m_Device, 
            VK_ACCELERATION_STRUCTURE_BUILD_TYPE_DEVICE_KHR, 
            &buildInfos,
            maxPrimCount.data(), 
            &sizeInfo
        );
 
        // Allocate the scratch buffer and setting the scratch info
        VulkanBuffer scratchBuffer(
            m_VulkanState, 
            "ScratchBuffer",
            sizeInfo.buildScratchSize, 
            VK_BUFFER_USAGE_STORAGE_BUFFER_BIT | 
            VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT, 
            0
        );
 
        VkBufferDeviceAddressInfo bufferInfo{};
        bufferInfo.sType                               = VK_STRUCTURE_TYPE_BUFFER_DEVICE_ADDRESS_INFO;
        bufferInfo.buffer                              = scratchBuffer.Get();
        buildInfos.scratchData.deviceAddress           = vkGetBufferDeviceAddress(m_VulkanState.m_Device, &bufferInfo);
 
        std::vector<const VkAccelerationStructureBuildRangeInfoKHR*> pBuildOffset(blas.asBuildOffsetInfo.size());
        for (size_t i = 0; i < blas.asBuildOffsetInfo.size(); i++)
        {
            pBuildOffset[i] = &blas.asBuildOffsetInfo[i];
        }
 
        // Update the instance buffer on the device side and build the TLAS
        VulkanCommandBuffer::CustomGraphicCmd(m_VulkanState, [&](const VkCommandBuffer& commandBuffer) {
            // Update the acceleration structure. Note the VK_TRUE parameter to trigger the update,
            // and the existing BLAS being passed and updated in place
            m_VulkanState.m_VkFunc.vkCmdBuildAccelerationStructuresKHR(commandBuffer, 1, &buildInfos, pBuildOffset.data());
        });
    }

References Spices::VulkanObject::m_VulkanState.