This operator sends a ray starting at origin
P and in the direction
specified by the normalized vector
I. The resulting color, opacity and
alpha will be returned.
The Bias parameter is typically a small number used to prevent self-refraction. The Max Contribution parameter is used to give the renderer an idea of how much the refracted light will contribute to the final pixel color, but has no effect on the results of this operator.
In order to prevent the renderer from computing standard transparency
(i.e. non-refracted transparency), the Of variable must be set to 1,1,1
to make the surface opaque. The
Af variable can be set to any value.
I are not connected, the global variables by the same
names will be used instead, and a local copy of the global
will be normalized inside this operator before the computation begins.