The RenderMan Interface - Paul Bourke

homogeneous two-dimensional mapping from parameter space to texture space. Special
cases of this mapping occur when the transformation reduces to a scale and an offset, which
is often used to piece patches together, or to an affine transformation, which is used to map
a collection of triangles onto a common planar texture.
The graphics state maintains a current set of texture coordinates. The correspondence between
these texture coordinates and the corners of the unit square is given by the following table.
Surface Parameters Texture Coordinates
(u,v)
(s,t)
(0,0) (s 1 , t 1 )
(1,0) (s 2 , t 2 )
(0,1) (s 3 , t 3 )
(1,1) (s 4 , t 4 )
By default, the texture coordinates at each corner are the same as the surface parameters
(s=u, t=v). Note that texture coordinates can also be explicitly attached to geometric primitives.
Note also that polygonal primitives are not parametric, and the current set of texture
coordinates do not apply to them.
RiTextureCoordinates ( RtFloat s1, RtFloat t1, RtFloat s2, RtFloat t2,
RtFloat s3, RtFloat t3, RtFloat s4, RtFloat t4 )
Set the current set of texture coordinates to the values passed as arguments according
to the above table.
RIB BINDING
TextureCoordinates s1 t1 s2 t2 s3 t3 s4 t4
TextureCoordinates [s1 t1 s2 t2 s3 t3 s4 t4]
EXAMPLE
RiTextureCoordinates (0.0, 0.0, 2.0, -0.5, -0.5, 1.75, 3.0, 3.0);
SEE ALSO
texture() and bump() in the Shading Language
4.2.3 Light sources
The graphics state maintains a current light source list. The lights in this list illuminate
subsequent surfaces. By making this list an attribute different light sources can be used to
illuminate different surfaces. Light sources can be added to this list by turning them on
and removed from this list by turning them off. Note that popping to a previous graphics
state also has the effect of returning the current light list to its previous value. Initially the
graphics state does not contain any lights.
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