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greg |
1.1 |
#ifndef lint
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greg |
2.8 |
static const char RCSid[] = "$Id: o_face.c,v 2.7 2014/07/08 18:25:00 greg Exp $";
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greg |
1.1 |
#endif
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/*
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* o_face.c - compute ray intersection with faces.
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greg |
2.2 |
*/
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greg |
2.3 |
#include "copyright.h"
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greg |
1.1 |
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#include "ray.h"
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#include "face.h"
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schorsch |
2.5 |
#include "rtotypes.h"
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greg |
1.1 |
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greg |
2.7 |
int
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schorsch |
2.5 |
o_face( /* compute intersection with polygonal face */
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OBJREC *o,
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greg |
2.7 |
RAY *r
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schorsch |
2.5 |
)
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greg |
1.1 |
{
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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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greg |
2.7 |
FACE *f; /* face record */
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greg |
1.1 |
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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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greg |
2.8 |
* 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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greg |
1.1 |
* 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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* is inside 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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greg |
2.8 |
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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greg |
1.1 |
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greg |
2.8 |
if (rayreject(o, r, t)) /* previous hit is better? */
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greg |
1.1 |
return(0);
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/* compute intersection */
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greg |
2.6 |
VSUM(pisect, r->rorg, r->rdir, t);
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greg |
1.1 |
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greg |
1.3 |
if (!inface(pisect, f)) /* ray intersects face? */
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return(0);
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greg |
1.1 |
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greg |
1.3 |
r->ro = o;
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r->rot = t;
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VCOPY(r->rop, pisect);
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VCOPY(r->ron, f->norm);
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r->rod = rdot;
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greg |
2.4 |
r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
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r->uv[0] = r->uv[1] = 0.0;
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greg |
1.4 |
r->rox = NULL;
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greg |
1.3 |
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greg |
1.1 |
return(1); /* hit */
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}
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