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/* Copyright (c) 1986 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* o_face.c - routines for creating octrees for polygonal faces. |
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* |
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* 5) If test 4 fails, we have no intersection. |
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*/ |
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o_face(o, cu) /* determine if face intersects cube */ |
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OBJREC *o; |
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CUBE *cu; |
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int |
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o_face( /* determine if face intersects cube */ |
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OBJREC *o, |
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CUBE *cu |
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) |
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{ |
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FVECT cumin, cumax; |
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FVECT v1, v2; |
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/* get face arguments */ |
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f = getface(o); |
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if (f->area == 0.0) /* empty face */ |
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return(0); |
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return(O_MISS); |
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/* compute cube boundaries */ |
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for (j = 0; j < 3; j++) |
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cumax[j] = (cumin[j] = cu->cuorg[j]) + cu->cusize; |
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cumax[j] = (cumin[j] = cu->cuorg[j]-FTINY) |
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+ cu->cusize + 2.0*FTINY; |
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vloc = ABOVE | BELOW; /* check vertices */ |
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for (i = 0; i < f->nv; i++) |
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if (j = plocate(VERTEX(f,i), cumin, cumax)) |
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if ( (j = plocate(VERTEX(f,i), cumin, cumax)) ) |
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vloc &= j; |
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else |
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return(1); /* vertex inside */ |
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return(O_HIT); /* vertex inside */ |
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if (vloc) /* all to one side */ |
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return(0); |
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return(O_MISS); |
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for (i = 0; i < f->nv; i++) { /* check edges */ |
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if ((j = i + 1) >= f->nv) |
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VCOPY(v1, VERTEX(f,i)); /* clip modifies */ |
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VCOPY(v2, VERTEX(f,j)); /* the vertices! */ |
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if (clip(v1, v2, cumin, cumax)) |
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return(1); /* edge inside */ |
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return(O_HIT); /* edge inside */ |
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} |
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/* see if cube cuts plane */ |
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for (j = 0; j < 3; j++) |
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v1[j] = cumax[j]; |
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v2[j] = cumin[j]; |
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} |
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if ((d1 = DOT(v1, f->norm) - f->const) > FTINY) |
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return(0); |
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if ((d2 = DOT(v2, f->norm) - f->const) < -FTINY) |
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return(0); |
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if ((d1 = DOT(v1, f->norm) - f->offset) > FTINY) |
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return(O_MISS); |
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if ((d2 = DOT(v2, f->norm) - f->offset) < -FTINY) |
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return(O_MISS); |
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/* intersect face */ |
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for (j = 0; j < 3; j++) |
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v1[j] = (v1[j]*d2 - v2[j]*d1)/(d2 - d1); |
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if (inface(v1, f)) |
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return(1); |
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return(O_HIT); |
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return(0); /* no intersection */ |
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return(O_MISS); /* no intersection */ |
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} |
