In a nutshell: DirectX 12 is getting better at ray tracing according to Microsoft. The DXR 1.0 API, which brought us that cool Star Wars Raytracing tech demo (below) last year, is moving to version 1.1 with features that provide greater efficiency and more flexibility. It is currently in testing, but should be available next year. DX12 will also have a slew of other features as well.
On Tuesday, Microsoft unveiled a whole new suite of features that will be in DirectX 12. The additions include Raytracing tier 1.1, Mesh Shader, Sampler Feedback, and more. Support is currently only available in preview builds for the Windows Insider Program, specifically 20H1, indicating a possible public release in the first half of 2020.
The DirectX Raytracing SDK (DXR tier 1.0) rolled out last year. Since then, game developers and GPU vendors, including Nvidia and Epic Games, have been making it tick, showing off photorealistic scenes rendered in real-time.
Working with developers and manufacturers, Microsoft has improved DXR tier 1.1. A list of enhancements includes:
- Support for adding extra shaders to an existing Raytracing PSO, which greatly increases efficiency of dynamic PSO additions.
- Support for ExecuteIndirect for Raytracing, which enables adaptive algorithms where the number of rays is decided on the GPU execution timeline.
- Inline Raytracing, which provides more direct control of the ray traversal algorithm and shader scheduling.
“DXR tier 1.1 is a superset of tier 1.0,” explained Microsoft. “Game developers should start building their raytracing solution based on the existing tier 1.0 APIs, then move up to tier 1.1 once they can better evaluate the benefit of tier 1.1 to their games.”
Mesh Shader is another new addition.
"[The DirectX Mesh Shader] is the next generation of GPU geometry processing,” claims the company.
It replaces the current input assembler, vertex shader, hull shader, tessellator, domain shader, and geometry shader. The feature will add efficiency and flexibility to the geometry pipeline (see above comparison).
“Mesh shaders can enhance performance by allowing geometry to be pre-culled without having to output new index buffers to memory, whereas triangles are currently only culled by fixed function hardware after the vertex shader has completed execution,” said the post.
DirectX Sampler Feedback allows games to generate a “Feedback Map” during rendering. This map will help games load only the textures needed for the most detailed MIP levels. Games, especially those with 4K assets, will have faster load times with lower memory pressure. Having Sampler Feedback improves texture streaming so that only the data that is needed is loaded into the stream. It also helps make texture-space shading more efficient by removing redundancies.
DirectX 12 will have several other features that Microsoft promised to provide technical details in the coming weeks along with all the features' specs