When b is not zero, this attribute causes that the xyz coordinates (or a transformation of them, see below) of geometric primitives are taken as texture coordinates.
If USEABSXYZTEXCS, see 6.4.15, was not set in an ancestor node, the local object coordinates are used, else the local object coordinates are first transformed into world coordinates, which afterwards are transformed into the coordinate system of this ancestor node.
In either case the resulting 3D texture coordinates can be further transformed via the matrix set by TEX3TRANSFORMS (see 6.3.2).
When b is zero, 2D texture coordinates are used. 2D texture coordinates can be created by nurbs surfaces and polygons but not by surfaces created with marching cube (these don't have a parametrization).
2D texture coordinates can be further transformed via the matrix set by TEX2TRANSFORMS (see 6.3.1).
b must be a number node.