| 37 |
|
|
| 38 |
|
#define EPSILON .0001 /* error allowed in fractal */ |
| 39 |
|
|
| 40 |
< |
#define frand3(x,y,z) frand((long)((12.38*(x)-22.30*(y)-42.63*(z))/EPSILON)) |
| 40 |
> |
#define frand3(x,y,z) frand(17*(x)+23*(y)+29*(z)) |
| 41 |
|
|
| 42 |
|
double fnoise3(); |
| 43 |
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|
| 165 |
|
|
| 166 |
|
double |
| 167 |
|
fnoise3(p) /* compute fractal noise function */ |
| 168 |
< |
register double p[3]; |
| 168 |
> |
double p[3]; |
| 169 |
|
{ |
| 170 |
|
double floor(); |
| 171 |
< |
double v[3], beg[3], fval[8], s, fc; |
| 172 |
< |
int closing, branch; |
| 171 |
> |
long t[3], v[3], beg[3], s; |
| 172 |
> |
double fval[8], fc; |
| 173 |
> |
int branch; |
| 174 |
|
register int i, j; |
| 175 |
|
/* get starting cube */ |
| 176 |
< |
for (i = 0; i < 3; i++) |
| 177 |
< |
beg[i] = floor(p[i]); |
| 176 |
> |
s = (long)(1.0/EPSILON); |
| 177 |
> |
for (i = 0; i < 3; i++) { |
| 178 |
> |
t[i] = s*p[i]; |
| 179 |
> |
beg[i] = s*floor(p[i]); |
| 180 |
> |
} |
| 181 |
|
for (j = 0; j < 8; j++) { |
| 182 |
|
for (i = 0; i < 3; i++) { |
| 183 |
|
v[i] = beg[i]; |
| 184 |
|
if (j & 1<<i) |
| 185 |
< |
v[i] += 1.0; |
| 185 |
> |
v[i] += s; |
| 186 |
|
} |
| 187 |
|
fval[j] = frand3(v[0],v[1],v[2]); |
| 188 |
|
} |
| 185 |
– |
s = 1.0; |
| 189 |
|
/* compute fractal */ |
| 190 |
|
for ( ; ; ) { |
| 191 |
< |
s *= 0.5; |
| 191 |
> |
s >>= 1; |
| 192 |
|
branch = 0; |
| 190 |
– |
closing = 0; |
| 193 |
|
for (i = 0; i < 3; i++) { /* do center */ |
| 194 |
|
v[i] = beg[i] + s; |
| 195 |
< |
if (p[i] > v[i]) { |
| 195 |
> |
if (t[i] > v[i]) { |
| 196 |
|
branch |= 1<<i; |
| 197 |
< |
if (p[i] - v[i] > EPSILON) |
| 196 |
< |
closing++; |
| 197 |
< |
} else if (v[i] - p[i] > EPSILON) |
| 198 |
< |
closing++; |
| 197 |
> |
} |
| 198 |
|
} |
| 199 |
|
fc = 0.0; |
| 200 |
|
for (j = 0; j < 8; j++) |
| 201 |
|
fc += fval[j]; |
| 202 |
< |
fc = 0.125*fc + s*frand3(v[0],v[1],v[2]); |
| 203 |
< |
if (closing == 0) |
| 202 |
> |
fc *= 0.125; |
| 203 |
> |
if (s < 1) |
| 204 |
|
return(fc); /* close enough */ |
| 205 |
+ |
fc += s*EPSILON*frand3(v[0],v[1],v[2]); |
| 206 |
|
fval[~branch & 7] = fc; |
| 207 |
|
for (i = 0; i < 3; i++) { /* do faces */ |
| 208 |
|
if (branch & 1<<i) |
| 213 |
|
for (j = 0; j < 8; j++) |
| 214 |
|
if (~(j^branch) & 1<<i) |
| 215 |
|
fc += fval[j]; |
| 216 |
< |
fc = 0.25*fc + s*frand3(v[0],v[1],v[2]); |
| 216 |
> |
fc = 0.25*fc + s*EPSILON*frand3(v[0],v[1],v[2]); |
| 217 |
|
fval[~(branch^1<<i) & 7] = fc; |
| 218 |
|
v[i] = beg[i] + s; |
| 219 |
|
} |
| 230 |
|
v[j] -= s; |
| 231 |
|
fc = fval[branch & ~(1<<i)]; |
| 232 |
|
fc += fval[branch | 1<<i]; |
| 233 |
< |
fc = 0.5*fc + s*frand3(v[0],v[1],v[2]); |
| 233 |
> |
fc = 0.5*fc + s*EPSILON*frand3(v[0],v[1],v[2]); |
| 234 |
|
fval[branch^1<<i] = fc; |
| 235 |
|
j = (i+1)%3; |
| 236 |
|
v[j] = beg[j] + s; |
