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#include "rtotypes.h" |
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extern int |
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int |
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o_face( /* compute intersection with polygonal face */ |
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OBJREC *o, |
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register RAY *r |
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RAY *r |
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) |
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{ |
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double rdot; /* direction . normal */ |
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double t; /* distance to intersection */ |
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FVECT pisect; /* intersection point */ |
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register FACE *f; /* face record */ |
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FACE *f; /* face record */ |
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f = getface(o); |
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/* |
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* First, we find the distance to the plane containing the |
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* face. If this distance is less than zero or greater |
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* than a previous intersection, we return. Otherwise, |
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* face. If the plane is parallel to our ray, or the |
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* previous hit was better, we return. Otherwise, |
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* we determine whether in fact the ray intersects the |
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* face. The ray intersects the face if the |
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* point of intersection with the plane of the face |
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*/ |
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/* compute dist. to plane */ |
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rdot = -DOT(r->rdir, f->norm); |
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if (rdot <= FTINY && rdot >= -FTINY) /* ray parallels plane */ |
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t = FHUGE; |
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else |
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t = (DOT(r->rorg, f->norm) - f->offset) / rdot; |
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if ((rdot <= FTINY) & (rdot >= -FTINY)) /* ray parallels plane */ |
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return(0); |
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t = (DOT(r->rorg, f->norm) - f->offset) / rdot; |
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if (t <= FTINY || t >= r->rot) /* not good enough */ |
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if (rayreject(o, r, t, rdot)) /* previous hit is better? */ |
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return(0); |
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/* compute intersection */ |
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VSUM(pisect, r->rorg, r->rdir, t); |
