Below is a list of features supported and unsupported in this phase one release of XPU
General
- XPU currently requires a CUDA-compatible GPU to be installed, even if the intention is to run only in CPU mode.
- Behavior of XPU when it runs out of memory on your GPU: XPU will crash if it runs out of memory on your GPU. If you are running XPU inside of Maya, Houdini, or Blender, this will bring down your application as well. Be sure to save often. We are going to work to mitigate the two biggest causes of this condition.
- Releasing a license: It is possible to get XPU into a situation where it doesn't release the license back to the RenderMan license server. If this happens and you end up using all of your licenses, just restart your application (Maya, Houdini, Katana, or Blender) and you will be able to continue your work.
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| Geometry | RIS | XPU | Notes |
|---|---|---|---|
Subdivision Surfaces | ✅ | ✅ | Catmull-Clark only |
Polygonal Surfaces | ✅ | ✅ | |
Nurbs | ✅ | ❌ | |
Curves | ✅ | ✅ | |
Points | ✅ | ✅ | Some features not available |
| Quadrics and Blobbies | ✅ | ❌ | |
| Procedurals | ✅ | ❌ | |
| Nested Instancing | ✅ | ✅ | Known Limitation: Varying attributes to drive differences in materials per-instance is not yet supported. Only 4 levels of nested instancing are supported. |
| Watertight dicing | ✅ | ✅ | XPU cannot opt out of watertight dicing |
...
| Pipeline | RIS | XPU | Notes |
|---|---|---|---|
AOVs and LPEs | ✅ | ❌ | |
EXR, TIFF | ✅ | ✅ | |
Deep Output | ✅ | ❌ | |
Matte, Holdouts | ✅ | ❌ | |
| PxrCamera | ✅ | ❌ | |
| Crop windows | ✅ | ❌ | |
| Advanced DOF controls (bokeh, etc) | ✅ | ❌ |
- XPU currently only outputs EXR or TIFF frames.
- Adaptive sampling is yet to be implemented.
- Motion blur has not been fully implemented. Transformation motion blur is fully functional, but deformation motion blur of geometry is not supported.
- Trace Subsets have not been implemented. This impacts the subsurfaceSubset feature of PxrSurface.
- Only some geometric built-in AOVs are available under the same name as they are available for RIS.
- Multi-camera, multi-frame is not yet supported.
- The built-in curvature calculation is different to RIS, which results in differences in specular mollification.
- The "weighted" option for the pixelfiltermode parameter to the Hider is not yet supported.
- Baking - either at the pattern level via PxrBakeTexture or at the renderer level to bake global illumination is not yet supported.
- Cached presence or opacity is not supported in XPU. XPU renders of transparent surfaces may be sharper as a result (they will not be biased by the micropolygon size).