#include "rmannotes.sl"

/*
 * tex_noise(): 
 */

surface
tex_perturb(float octaves	= 6,
		lacunarity	= 2,
		scale		= 5,
		brightness	= 0,
		contrast	= 3,
		distort		= 1;
	string	texmap		= "" )
{

	float i, size, ss, tt;
	float sum;
	color Ctex;
	size = scale;
    	point Psh;
    	
    	sum = 0.0;
    	for (i=0; i < octaves; i+=1)
    	{
    		sum += (( float noise(s*size, t*size)-0.5 ) * 2.0) / size;
    		size *= lacunarity;
    	}
	sum = ((sum + (brightness - 0.5)) * contrast) + 0.5;

    	ss = mod( (s + sum*distort), 1 );
    	tt = mod( (t + sum*distort), 1 );
    	
    	Psh = point(ss, tt, 0);

	Ctex = texture(texmap, xcomp(Psh), ycomp(Psh));

    	Ci = Ctex;
}