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38 |
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#define EPSILON .0001 /* error allowed in fractal */ |
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< |
#define frand3(x,y,z) frand((long)((12.38*(x)-22.30*(y)-42.63*(z))/EPSILON)) |
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> |
#define frand3(x,y,z) frand(17*(x)+23*(y)+29*(z)) |
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42 |
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double fnoise3(); |
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double |
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fnoise3(p) /* compute fractal noise function */ |
168 |
< |
register double p[3]; |
168 |
> |
double p[3]; |
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{ |
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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; |
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register int i, j; |
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/* 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 |
> |
} |
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for (j = 0; j < 8; j++) { |
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for (i = 0; i < 3; i++) { |
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v[i] = beg[i]; |
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if (j & 1<<i) |
185 |
< |
v[i] += 1.0; |
185 |
> |
v[i] += s; |
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} |
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fval[j] = frand3(v[0],v[1],v[2]); |
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} |
185 |
– |
s = 1.0; |
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/* compute fractal */ |
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for ( ; ; ) { |
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< |
s *= 0.5; |
191 |
> |
s >>= 1; |
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branch = 0; |
190 |
– |
closing = 0; |
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for (i = 0; i < 3; i++) { /* do center */ |
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v[i] = beg[i] + s; |
195 |
< |
if (p[i] > v[i]) { |
195 |
> |
if (t[i] > v[i]) { |
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branch |= 1<<i; |
197 |
< |
if (p[i] - v[i] > EPSILON) |
196 |
< |
closing++; |
197 |
< |
} else if (v[i] - p[i] > EPSILON) |
198 |
< |
closing++; |
197 |
> |
} |
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} |
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fc = 0.0; |
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for (j = 0; j < 8; j++) |
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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) |
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return(fc); /* close enough */ |
205 |
+ |
fc += s*EPSILON*frand3(v[0],v[1],v[2]); |
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fval[~branch & 7] = fc; |
207 |
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for (i = 0; i < 3; i++) { /* do faces */ |
208 |
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if (branch & 1<<i) |
213 |
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for (j = 0; j < 8; j++) |
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if (~(j^branch) & 1<<i) |
215 |
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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]); |
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fval[~(branch^1<<i) & 7] = fc; |
218 |
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v[i] = beg[i] + s; |
219 |
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} |
230 |
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v[j] -= s; |
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fc = fval[branch & ~(1<<i)]; |
232 |
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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 |
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fval[branch^1<<i] = fc; |
235 |
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j = (i+1)%3; |
236 |
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v[j] = beg[j] + s; |