The RenderMan Interface - Paul Bourke

A.4 Volume Shaders
A.4.1
Depth cue shader
volume
depthcue(
float mindistance = 0, maxdistance = 1;
color background = 0;)
{
float d;
d = clamp((depth(P) - mindistance) /
(maxdistance - mindistance), 0.0, 1.0);
Ci = mix(Ci, background, d);
Oi = mix(Oi, color(1, 1, 1), d);
}
A.4.2
Fog shader
volume
fog(float distance = 1; color background = 0;)
{
float d;
d = 1 - exp(-length(I) / distance);
Ci = mix(Ci, background, d);
Oi = mix(Oi, color(1, 1, 1), d);
}
A.5 Displacement Shaders
A.5.1
Bumpy shader
displacement
bumpy(
float Km = 1;
string texturename = ””;)
{
float amp = Km * float texture(texturename, s, t);
P += amp * normalize(N);
N = calculatenormal(P);
}
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