Try
Ray Tracing bringup
This ticket is to track ray-query/ray-tracing work
command line: Gothic2Notr.exe -rt
- [x] Engine api bring-up
- [x] Static mesh support
- [x] Textures support (Vulkan only for now)
- [ ] Animated meshes
Issues:
- in DX12 backend shader compiler crashes from time-to-time - need to investigate (https://github.com/microsoft/DirectXShaderCompiler/issues/4394)
- in Metal spir-v cross generates seemingly invalid code for RQ shader (https://github.com/KhronosGroup/SPIRV-Cross/issues/1910)
- Vulkan implementation might suffer from dangling-pointers/missing barriers - need to verify with spec and do more testing
Notes: blas/tlas performance is quite inconsistent. Having same landscape geometry at one mesh and as multi-mesh about 4x fps difference:
| FPS | Method |
|---|---|
| 40.4 | multi-mesh land + objects |
| 40 | multi-mesh land |
| 200 | objects |
| 185 | single-mesh land |
| 163 | single-mesh land + obj |
GPU is RTX 3070
This performance change can be explained by: https://developer.nvidia.com/blog/best-practices-using-nvidia-rtx-ray-tracing/ :
Organizing geometries into BLASes
Consider splitting a BLAS when there is a lot of empty space in an instance’s world-space AABB. World-space AABBs are used to test whether a ray potentially hits an instance and traversing its associated BLAS is required. A significant amount of empty space can lead to unnecessary traversal through the BLAS. Geometries that move independently should usually be in their own BLASes. Merging them into a single BLAS can easily lead to an AABB with lots of empty space, and likely lead to unnecessary rebuilding of the BLAS instead of simply changing transformations of the independent instances.
Still annoying; material indexing is gonna be more difficult
Bindless turnout to be non-trivial in many ways, works only on Vulkan backend for now, with texture-array capt at 4096 unique textures.
More about Bindless problems: https://github.com/Try/Tempest/issues/36
