vk_raytracing_tutorial_KHR | Ray tracing examples and tutorials | Learning library

I've been following along in the (very awesome) nvpro raytracing tutorial and have a question about the way the CameraProperties uniform buffer is bound using layout(binding = 0, set = 1) - I understand the binding = 0, but why set = 1?

The tutorial says "The set = 1 comes from the fact that it is the second descriptor set passed to pipelineLayoutCreateInfo.setPSetLayouts", but when I look at HelloVulkan::createGraphicsPipeline() I see the layout count is one, and this is where m_descSetLayout (what binds the camera uniform buffer) is used. What am I missing?

The related section of the tutorial is here.

Thanks!

Recently, I added support for the VK_KHR_ray_tracing extension in my Vulkan framework with this tutorial as a template. Unfortunately, it doesn't handle acceleration structure updates.

I figured out that rebuilding is quite similar to first building it. The only difference is setting the update field on VkAccelerationStructureBuildGeometryInfoKHR to VK_TRUE and set the src and dst acceleration structures accordingly. Currently, I use the same VkAccelerationStructureKHR for src and dst, i.e. it is updating itself, which is according to the specification:

If update is VK_TRUE, the srcAccelerationStructure and dstAccelerationStructure objects must either be the same object or not have any memory aliasing

In my application, the TLAS is rebuilt every frame (dynamic objects) and this works well except for constantly getting a validation error:

If update is VK_TRUE, srcAccelerationStructure must have been built before with VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_UPDATE_BIT_KHR set in VkAccelerationStructureBuildGeometryInfoKHR::flags (https://vulkan.lunarg.com/doc/view/1.2.141.0/windows/1.2-extensions/vkspec.html#VUID-VkAccelerationStructureBuildGeometryInfoKHR-update-03538)

However, during debugging, the VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_UPDATE_BIT_KHR flag is set on every vkCmdBuildAccelerationStructureKHR call.

My best guess is that this is a bug in the vulkan beta drivers of Nvidia (457.33) but there might also be something else wrong which is not caught by the validation layers.

Has anybody experience with the VK_KHR_ray_tracing extensions and managed to get acceleration structure updates working without any validation errors?

EDIT: The linked tutorial also has a sample with animations and TLAS updates, see here. When running this sample, the same validation error comes up.