POV-Ray

The request is difficult to implement with the current code as it was never meant to be as universally useful as it turned out to be. The solution will have to be part of the 4.0 parser rewrite, and one good option will be to base the new function parser on llvm.

If there is a parser rewrite in the future, functions returning vectors/colors could also be implemented (vectors as input are easily separated into components already, but functions returning vectors are now almost inexistent). A standing workaround is
function { pigment { function {} color_map{} }}
which is ugly.

Such functions would simplify all existing syntax. Splines actually already behave as vector-valued functions of one parameter. Now, one could also specify parametric curves (vector-valued functions with 1 parameter), parametric surfaces (2 parameters) or patterns (3 parameters), or more parameters, if you need more variables. One could then have

parametric {

v_function { my_function(u,v) }
translate my_other_function(parameter1,parameter2)
texture {
   pigment {
      v_function { my_color_function(x,y,z) }
   }
   normal {
      v_function { my_normal_function(x+y+z,0) }
   }
}

}

This would also enable using pigments and functions interchangeably: users could define their own color patterns, or use existing patterns as functions (now this is patched through builtin functions in "functions.inc"). The vector-valued functions could provide a one-shot solution for displacement warps, normal maps (they would be normalized first by the code), or other

Is there any particular reason that patterns and functions are now treated differently by povray?

Now tracked on github as issue #190.