The RenderMan Interface - Paul Bourke

{
}
float IdotN = I.N;
float k = 1 - eta*eta*(1 - IdotN*IdotN);
return k < 0 (0,0,0) : eta*I - (eta*IdotN + sqrt(k))*N;
Return the transmitted vector given an incident direction I, the normal vector N and
the relative index of refraction eta. eta is the ratio of the index of refraction in the volume
containing the incident vector to that of the volume being entered. This vector
is computed using Snell’s law. If the returned vector has zero length, then there is no
transmitted light because of total internal reflection.
fresnel( vector I, N; float eta; output float Kr, Kt; [output vector R, T] )
Return the reflection coefficient Kr and refraction (or transmission) coefficient Kt
given an incident direction I, the surface normal N, and the relative index of refraction
eta. eta is the ratio of the index of refraction in the volume containing the incident
vector to that of the volume being entered. These coefficients are computed using
the Fresnel formula. Optionally, this procedure also returns the reflected (R) and
transmitted (T ) vectors. The transmitted vector is computed using Snell’s law.
point transform( string tospace; point p )
point transform( string fromspace, tospace; point p )
point transform( matrix m; point p )
point transform( string fromspace; matrix m; point p )
vector vtransform( string tospace; vector v )
vector vtransform( string fromspace, tospace; vector v )
vector vtransform( matrix m; vector v )
vector vtransform( string fromspace; matrix m; vector v )
normal ntransform( string tospace; normal n )
normal ntransform( string fromspace, tospace; normal n )
normal ntransform( matrix m; normal n )
normal ntransform( string fromspace; matrix m; normal n )
The transform function transforms the point p from the coordinate system fromspace
to the coordinate system tospace. If fromspace is absent, it is assumed to be the ”current”
coordinate system. A transformation matrix may be given instead of a tospace
name. The vtransform and ntransform functions perform the equivalent coordinate
system transformations on vectors and normals, respectively.
float depth( point P )
Return the depth of the point P in camera coordinates. The depth is normalized to
lie between 0 (at the near clipping plane) and 1 (at the far clipping plane).
point
calculatenormal( point P )
{
return Du(P) ˆ Dv(P);
}
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