Adds four new grid operator nodes that wrap OpenVDB's differential
operators. All nodes take a grid input and output a grid, potentially
with a different data type.
New nodes:
- Grid Curl: Calculate curl of vector field (Vec3 → Vec3)
- Grid Divergence: Calculate divergence of vector field (Vec3 → Float)
- Grid Gradient: Calculate gradient of scalar field (Float → Vec3)
- Grid Laplacian: Calculate Laplacian of scalar field (Float → Float)
These operators enable vector calculus operations on volume grids for
effects like flow analysis, vortex detection, etc.
Co-authored-by: Hans Goudey <hans@blender.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/146845