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SPAkern Global Function bs3_surface_perp

void bs3_surface_perp(	SPAposition const&	`point`,
	bs3_surface	`bs`,
	SPAposition&	`foot`,
	SPAunit_vector&	`norm`,
	SPApar_pos const&	`uv_guess`	`= (SPApar_pos )NULL_REF`,
	SPApar_pos&	`uv_actual`	`= (SPApar_pos )NULL_REF`,
	SPApar_box const&	`var`	`= (SPApar_box )NULL_REF` )

Gets the intersection with the surface and the normal to the surface of a perpendicular dropped from a point to the surface.

Role: If an initial guess of the parameter values for the foot of the perpendicular is given, it is assumed to be close to the desired position, allowing faster processing.

For an open surface, there may be no perpendicular at all if the given point is beyond the boundary. In this case, a perpendicular will be dropped to a boundary edge, even though this is not perpendicular to the surface itself. If there is no perpendicular to the edges, then one of the corners will be returned as the foot. The normal direction will always be the normal to the surface at the foot.

Errors: Returns without setting any arguments if the input surface is NULL.

Effect: Read-only

Parameters:

point: given point.
bs: given surface.
foot: returned foot of perpendicular.
norm: returned normal.
uv_guess: returned guess uv if known.
uv_actual: returned actual uv used.
var: var.

This object is included in the file: sp3srtn.hxx