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SPAkern Global Function bs3_surface_invdir

SPApar_dir bs3_surface_invdir(	SPAunit_vector const&	`dir`,
	SPApar_pos const&	`uv`,
	bs3_surface	`bs`)

Gets the direction in the parameter space of a surface at a given position that corresponds to a given object-space tangent direction.

Role: Usually, this routine will normalize the result of calling bs3_surface_unitvec.

Errors: Returns an empty SPApar_dir if the input surface is NULL.

Limitations: Results are not defined for points that do not lie on the surface.

Effect: Read-only

Parameters:

dir: given direction.
uv: given parameter point.
bs: given surface.

This object is included in the file: sp3srtn.hxx