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In Katana, you can specify the surface orientation (normal direc= tion) of objects using the PrmanObjectStatements node.
The handedness of a coordinate system is referred to as its orientation.= The initial "camera" coordinate system is left-handed: x points right, y p= oint up, and z points in. Transformations, however, can flip the orientatio= n of the current coordinate system. An example of a transformation that doe= s not preserve orientation is a reflection.
Similarly, geometric primitives have an orientation, which determines wh= ether their surface normals are defined using a right-handed or left-handed= rule in their object coordinate system. RfK assume right-handed orientatio= n: x points right, y point up, and z points out. Positive rotation is counterclockwise. If a primi= tive is inside-out, its normal will be computed so that it points in the op= posite direction. This has implications for culling, shading, and solids (n= ested dielectrics for example). The outside surface of a primitive is the s= ide from which the normal points outward; the inside surface is the opposit= e side. The interior of a solid is the volume that is adjacent to the insid= e surface and the exterior is the region adjacent to the outside.
If the current orientation is not the same as the orientation of the cur= rent coordinate system, geometric primitives are turned inside out, and the= ir normals are automatically flipped.
Below the teapot create macro is rendered with sides =3D 1, meaning only= single sided. Black teapots indicates the object normals are inward facing= , by default PxrSurface does not shade the inside of non-transmissive objec= ts.
Sides options: