Typically, when VOPs cook geometry, the SOPs will try to do the right thing with the
normal attribute. That is, if the
P attribute is modified, the
normal attribute will usually be out of date. The right thing is usually to re-compute the point normals whenever
P changes (provided the VEX code doesn’t modify
N on its own).
However, in some cases, you may want finer control over how the
normal attribute is handled. There are three possible choices provided:
No modification to N:
The VEX code will leave the
Re-compute N if P changes (default):
The VEX code will recompute the
Nattribute, if the
Pattribute is changed.
Forcibly recompute N:
The VEX code will recompute normals, regardless of whether