This patch unifies the anti-aliasing of plane deforms between the CPU
and GPU compositors. The CPU used a multi-sample approach, where the
mask was computed 8 times with a jitter, then averaged to get smooth
edges. The GPU relied on the anisotropic filtering with zero boundaries
to smooth the edges.
Furthermore, the CPU implementation ignored the anti-aliasing for the
deformed image and also relied anisotropic filtering like the GPU, so
its outputs were different.
To unify both implementation, we use the existing SMAA anti-aliasing
algorithm instead, and use the anti-aliased mask for the image output as
well. This affects both the Corner Pin and Plane Deform nodes.
A consequence of this change for the Plane Deform node is that motion
blur will appear to have less samples, that's because it was sampled
8-times more in the previous implementation. But users can just increase
the samples in the node to account for that.
Pull Request: https://projects.blender.org/blender/blender/pulls/118853
Omar Emara
1bff17cc99