The RenderMan Interface - Paul Bourke

These functions compute power and inverse power functions. pow returns x y , exp
returns e x . sqrt returns the positive square root of x, and inversesqrt(x) returns
1/sqrt(x). log with one argument returns the natural logarithm of x (x = log(exp(x))).
log with two arguments returns the logarithm in the specified base (x = log(pow(base,
x), base)).
float mod ( float a, b )
float abs ( float x )
float sign ( float x )
mod returns a value greater than 0 and less than or equal to b such that mod(a,b)
= a - n*b for some integer n. abs returns the absolute value of its argument and sign
returns -1 if its argument is negative, 1 if its argument is positive, and 0 if its argument
is zero.
type min (type a, b, ... )
type max ( type a, b, ... )
type clamp ( type a, min, max )
min takes a list of two or more arguments of identical type and returns the argument
with minimum value; max returns the argument with maximum value. clamp(a,min,max)
returns min if a is less than min, max if a is greater than max; otherwise it returns a.
The type may be any of float, point, vector, normal, or color. The variants that operate
on colors or point-like objects operate on a component-by-component basis (e.g.,
separately for x, y, and z).
float mix (float x, y; float alpha )
point mix (point x, y; float alpha )
vector mix (vector x, y; float alpha )
normal mix (normal x, y; float alpha )
color mix (color x, y; float alpha )
mix returns x · (1 − α) + y · α, that is, it performs a linear blend between values x
and y. The types of x and y must be identical, but may be any of float, point, vector,
normal, or color. The variants that operate on colors or point-like objects operate on
a component-by-component basis (e.g., separately for x, y, and z).
float floor ( float x )
float ceil ( float x )
float round ( float x )
floor returns the largest integer (expressed as a float) not greater than x. ceil returns
the smallest integer (expressed as a float) not smaller than x. round returns the integer
closest to x.
float step ( float min, value )
float smoothstep ( float min, max, value )
134