Add a simple node to compute the intersection, difference, or union
between SDF grids. This should be the first new use case for the
new volume grid nodes that wasn't possible before.
For naming and multi-inputs, the node uses the same design as the
mesh boolean node. We considered splitting each operation into a
separate node, but though most users considered these different
"modes" of the same operation.
One thing to keep in mind is that it's important for the grids to
have exactly the same transform. If they have different transforms,
the second grid must be resampled to match the first, because the
OpenVDB CSG tools have that requirement. Resampling is expensive
(for SDF grids it means a grid -> mesh -> grid round trip) and should
be avoided.
Pull Request: https://projects.blender.org/blender/blender/pulls/118879
0c3763ddda