The RenderMan Interface - Paul Bourke

the exterior is the region adjacent to the outside. This is discussed further in the section on
Geometric Primitives.
The current orientation of primitives is maintained as part of the graphics state independent
of the orientation of the current coordinate system. The current orientation is initially set
to match the orientation of the initial coordinate system, and always flips whenever the
orientation of the current coordinate system flips. It can also be modified directly with
RiOrientation and RiReverseOrientation. If the current orientation is not the same as the
orientation of the current coordinate system, geometric primitives are turned inside out,
and their normals are automatically flipped.
RiOrientation ( RtToken orientation )
This procedure sets the current orientation to be either ”outside” (to match the current
coordinate system), ”inside” (to be the opposite of the current coordinate system), ”lh”
(for explicit left-handed orientation) or ”rh” (for explicit right-handed orientation).
RIB BINDING
Orientation orientation
EXAMPLE
Orientation ”lh”
SEE ALSO
ReverseOrientation
RiReverseOrientation ()
Causes the current orientation to be toggled. If the orientation was right-handed it is
now left-handed, and vice versa.
RIB BINDING
ReverseOrientation-
EXAMPLE
RiReverseOrientation ();
SEE ALSO
RiOrientation
Objects can be two-sided or one-sided. Both the inside and the outside surface of two-sided
objects are visible, whereas only the outside surface of a one-sided object is visible. If the
outside of a one-sided surface faces the viewer, the surface is said to be frontfacing, and if
the outside surface faces away from the viewer, the surface is backfacing. Normally closed
surfaces should be defined as one-sided and open surfaces should be defined as two-sided.
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