{ RCSid $Id: noise.cal,v 1.3 2018/11/21 17:45:45 greg Exp $ }
{ 1-D Perlin Noise function }

frac(x):x-floor(x);

hermite(p0,p1,r0,r1,t) :	p0 * ((2*t-3)*t*t+1) +
				p1 * (-2*t+3)*t*t +
				r0 * (((t-2)*t+1)*t) +
				r1 * ((t-1)*t*t);

rand2a(x) : 1-2*rand(.69692*x);
rand2b(x) : 1-2*rand(.05393*x);

noise_1(xl,xd,xu) : hermite(
				rand2a(xl),
				rand2a(xu),
				rand2b(xl),
				rand2b(xu),
				xd);

noise(x) : noise_1(floor(x),frac(x),ceil(x));