/* Copyright (c) 1988 Regents of the University of California */ #ifndef lint static char SCCSid[] = "@(#)noise3.c 2.1 11/12/91 LBL"; #endif /* * noise3.c - noise functions for random textures. * * Credit for the smooth algorithm goes to Ken Perlin. * (ref. SIGGRAPH Vol 19, No 3, pp 287-96) * * 4/15/86 * 5/19/88 Added fractal noise function */ #define A 0 #define B 1 #define C 2 #define D 3 #define rand3a(x,y,z) frand(67*(x)+59*(y)+71*(z)) #define rand3b(x,y,z) frand(73*(x)+79*(y)+83*(z)) #define rand3c(x,y,z) frand(89*(x)+97*(y)+101*(z)) #define rand3d(x,y,z) frand(103*(x)+107*(y)+109*(z)) /* hermite */ #define hpoly1(t) ((2.0*t-3.0)*t*t+1.0) #define hpoly2(t) (-2.0*t+3.0)*t*t #define hpoly3(t) ((t-2.0)*t+1.0)*t #define hpoly4(t) (t-1.0)*t*t double *noise3(), fnoise3(), frand(); static interpolate(); static long xlim[3][2]; static double xarg[3]; #define EPSILON .0001 /* error allowed in fractal */ #define frand3(x,y,z) frand(17*(x)+23*(y)+29*(z)) double * noise3(xnew) /* compute the noise function */ register double xnew[3]; { extern double floor(); static double x[3] = {-100000.0, -100000.0, -100000.0}; static double f[4]; if (x[0]==xnew[0] && x[1]==xnew[1] && x[2]==xnew[2]) return(f); x[0] = xnew[0]; x[1] = xnew[1]; x[2] = xnew[2]; xlim[0][0] = floor(x[0]); xlim[0][1] = xlim[0][0] + 1; xlim[1][0] = floor(x[1]); xlim[1][1] = xlim[1][0] + 1; xlim[2][0] = floor(x[2]); xlim[2][1] = xlim[2][0] + 1; xarg[0] = x[0] - xlim[0][0]; xarg[1] = x[1] - xlim[1][0]; xarg[2] = x[2] - xlim[2][0]; interpolate(f, 0, 3); return(f); } static interpolate(f, i, n) double f[4]; register int i, n; { double f0[4], f1[4], hp1, hp2; if (n == 0) { f[A] = rand3a(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]); f[B] = rand3b(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]); f[C] = rand3c(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]); f[D] = rand3d(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]); } else { n--; interpolate(f0, i, n); interpolate(f1, i | 1<>= 1) == 0) return(fc); /* close enough */ branch = 0; for (i = 0; i < 3; i++) { /* do center */ v[i] = beg[i] + s; if (t[i] > v[i]) { branch |= 1<