Previously with adaptive subdivision this happened to work with the N
attribute, but that was not meant to be undisplaced. This adds a new
undisplaced_N attribute specifically for this purpose.
For backwards compatibility in Blender 4.5, this also keeps N undisplaced.
But that will be changed in 5.0.
Pull Request: https://projects.blender.org/blender/blender/pulls/142090
* Perform attribute interpolation as part of dicing.
* Remove temporary subd uv and face index attributes.
On a MacBook M3 with 12 P-cores and 4 E-cores, these changes overall give
a 10x-14x speedup on various scenes. Note that splitting is still single
threaded and can be expensive, and UV subdivision can be optimized more.
Pull Request: https://projects.blender.org/blender/blender/pulls/136411
* Add SubdAttributeInterpolation class for linear attribute interpolation.
* Dicing computes ptex UV and face ID for interpolation.
* Simplify mesh storage of subd primitive counts
* Remove kernel code for subd attribute interpolation
* Remove patch table packing and upload
The old optimization adds a fair amount of complexity to the kernel, affecting
performance even when not using the feature. It's also not that useful as it
does not work for UVs that needs special interpolation. With this simpler code
it should be easier to make it feature complete.
Pull Request: https://projects.blender.org/blender/blender/pulls/135681
