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#ifndef lint |
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static const char RCSid[] = "$Id: tmesh.c,v 2.5 2006/03/02 17:16:56 greg Exp $"; |
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#endif |
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/* |
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* Compute and print barycentric coordinates for triangle meshes |
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*/ |
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|
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#include <stdio.h> |
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#include "fvect.h" |
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#include "tmesh.h" |
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|
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|
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int |
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flat_tri( /* determine if triangle is flat */ |
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FVECT v1, |
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FVECT v2, |
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FVECT v3, |
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FVECT n1, |
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FVECT n2, |
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FVECT n3 |
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) |
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{ |
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double d1, d2, d3; |
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FVECT vt1, vt2, vn; |
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/* compute default normal */ |
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VSUB(vt1, v2, v1); |
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VSUB(vt2, v3, v2); |
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VCROSS(vn, vt1, vt2); |
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if (normalize(vn) == 0.0) |
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return(DEGEN); |
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/* compare to supplied normals */ |
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d1 = DOT(vn, n1); d2 = DOT(vn, n2); d3 = DOT(vn, n3); |
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if (d1 < 0 && d2 < 0 && d3 < 0) { |
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if (d1 > -COSTOL || d2 > -COSTOL || d3 > -COSTOL) |
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return(RVBENT); |
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return(RVFLAT); |
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} |
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if (d1 < COSTOL || d2 < COSTOL || d3 < COSTOL) |
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return(ISBENT); |
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return(ISFLAT); |
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} |
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|
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|
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int |
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comp_baryc( /* compute barycentric vectors */ |
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BARYCCM *bcm, |
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RREAL *v1, |
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RREAL *v2, |
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RREAL *v3 |
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) |
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{ |
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RREAL *vt; |
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FVECT va, vab, vcb; |
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double d; |
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int ax0, ax1; |
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int i; |
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/* compute major axis */ |
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VSUB(vab, v1, v2); |
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VSUB(vcb, v3, v2); |
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VCROSS(va, vab, vcb); |
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bcm->ax = (va[1]*va[1] > va[0]*va[0]); |
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if (va[2]*va[2] > va[bcm->ax]*va[bcm->ax]) bcm->ax = 2; |
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ax0 = (bcm->ax + 1)%3; |
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ax1 = (bcm->ax + 2)%3; |
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for (i = 0; i < 2; i++) { |
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vab[0] = v1[ax0] - v2[ax0]; |
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vcb[0] = v3[ax0] - v2[ax0]; |
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vab[1] = v1[ax1] - v2[ax1]; |
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vcb[1] = v3[ax1] - v2[ax1]; |
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d = vcb[0]*vcb[0] + vcb[1]*vcb[1]; |
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if (d <= FTINY*FTINY) |
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return(-1); |
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d = (vcb[0]*vab[0] + vcb[1]*vab[1])/d; |
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va[0] = vab[0] - vcb[0]*d; |
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va[1] = vab[1] - vcb[1]*d; |
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d = va[0]*va[0] + va[1]*va[1]; |
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if (d <= FTINY*FTINY) |
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return(-1); |
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d = 1.0/d; |
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bcm->tm[i][0] = va[0] *= d; |
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bcm->tm[i][1] = va[1] *= d; |
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bcm->tm[i][2] = -(v2[ax0]*va[0] + v2[ax1]*va[1]); |
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/* rotate vertices */ |
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vt = v1; |
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v1 = v2; |
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v2 = v3; |
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v3 = vt; |
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} |
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return(0); |
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} |
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|
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|
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void |
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eval_baryc( /* evaluate barycentric weights at p */ |
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RREAL wt[3], |
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FVECT p, |
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BARYCCM *bcm |
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) |
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{ |
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double u, v; |
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int i; |
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|
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if ((i = bcm->ax + 1) >= 3) i -= 3; |
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u = p[i]; |
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if (++i >= 3) i -= 3; |
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v = p[i]; |
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wt[0] = u*bcm->tm[0][0] + v*bcm->tm[0][1] + bcm->tm[0][2]; |
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wt[1] = u*bcm->tm[1][0] + v*bcm->tm[1][1] + bcm->tm[1][2]; |
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wt[2] = 1. - wt[1] - wt[0]; |
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} |
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|
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|
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int |
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get_baryc( /* compute barycentric weights at p */ |
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RREAL wt[3], |
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FVECT p, |
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FVECT v1, |
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FVECT v2, |
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FVECT v3 |
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) |
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{ |
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BARYCCM bcm; |
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|
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if (comp_baryc(&bcm, v1, v2, v3) < 0) |
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return(-1); |
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eval_baryc(wt, p, &bcm); |
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return(0); |
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} |
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|
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|
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#if 0 |
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int |
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get_baryc(wt, p, v1, v2, v3) /* compute barycentric weights at p */ |
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RREAL wt[3]; |
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FVECT p; |
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FVECT v1, v2, v3; |
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{ |
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FVECT ac, bc, pc, cros; |
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double normf; |
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/* area formula w/o 2-D optimization */ |
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VSUB(ac, v1, v3); |
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VSUB(bc, v2, v3); |
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VSUB(pc, p, v3); |
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VCROSS(cros, ac, bc); |
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normf = DOT(cros,cros) |
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if (normf <= 0.0) |
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return(-1); |
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normf = 1./sqrt(normf); |
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VCROSS(cros, bc, pc); |
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wt[0] = VLEN(cros) * normf; |
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VCROSS(cros, ac, pc); |
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wt[1] = VLEN(cros) * normf; |
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wt[2] = 1. - wt[1] - wt[0]; |
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return(0); |
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} |
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#endif |
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|
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|
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void |
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fput_baryc( /* put barycentric coord. vectors */ |
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BARYCCM *bcm, |
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RREAL com[][3], |
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int n, |
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FILE *fp |
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) |
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{ |
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double a, b; |
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int i; |
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|
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fprintf(fp, "%d\t%d\n", 1+3*n, bcm->ax); |
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for (i = 0; i < n; i++) { |
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a = com[i][0] - com[i][2]; |
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b = com[i][1] - com[i][2]; |
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fprintf(fp, "%14.8f %14.8f %14.8f\n", |
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bcm->tm[0][0]*a + bcm->tm[1][0]*b, |
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bcm->tm[0][1]*a + bcm->tm[1][1]*b, |
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bcm->tm[0][2]*a + bcm->tm[1][2]*b + com[i][2]); |
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} |
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} |
