This operator sends a ray from the position
P along the direction
specified by the direction
D, and returns the distance to the object
intersected or a negative number if not object found. The position and
normal of the intersected surface are returned in
The length of the
D vector represents the farthest distance considered
when checking for intersections.
If the position (
P) input is not connected, the global variable by the
same name will be used instead.