Background Information and Techniques - Computer Animation: Algorithms and Techniques - page 467

{
float *table ¼ valueTab;
int i;
srand(seed);
for (i ¼ 0; i < TABSIZE; i þþ )
*(table þþ ) ¼ 1.0 -2.0*RANDNBR;
}
/* ¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼ */
/* LATTICE function */
/* returns a value corresponding to the lattice point */
float lattice(int ix, int iy, int iz)
{
return valueTab[INDEX(ix,iy,iz)];
}
/* ¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼¼ */
/* NOISE function */
float noise(float x, float y, float z)
{
int ix,iy,iz;
int i,j,k;
float fx,fy,fz;
float xknots[4],yknots[4],zknots[4];
static int initialized ¼ 0;
if (!initialized) {
valueTableInit(665);
initialized ¼ 1;
}
ix ¼ FLOOR(x);
fx ¼ x - ix;
iy ¼ FLOOR(y);
fy ¼ y - iy;
iz ¼ FLOOR(z);
fz ¼ z-iz;
for (k ¼ -1; k <¼ 2; k þþ ){
for (j ¼ -1; j <¼ 2; j þþ ){
for (i ¼ -1; i <¼ 2; i þþ )[i þ 1] ¼ lattice(ix þ i,iy þ j,iz þ k);
yknots[j þ 1] ¼ spline(fx,xknots);
}
zknots[k þ 1] ¼ spline(fy,yknots);
}
return spline(fz,zknots);
}
#define FP00 -0.5
#define FP01 1.5
#define FP02 -1.5
#define FP03 0.5
#define FP10 1.0