src/rt/o_face.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 *  o_face.c - compute ray intersection with faces.
 */

#include "copyright.h"

#include  "ray.h"

#include  "face.h"


o_face(o, r)            /* compute intersection with polygonal face */
OBJREC  *o;
register RAY  *r;
{
        double  rdot;           /* direction . normal */
        double  t;              /* distance to intersection */
        FVECT  pisect;          /* intersection point */
        register FACE  *f;      /* face record */
        register int  i;

        f = getface(o);
                
        /*
         *  First, we find the distance to the plane containing the
         *  face.  If this distance is less than zero or greater
         *  than a previous intersection, we return.  Otherwise,
         *  we determine whether in fact the ray intersects the
         *  face.  The ray intersects the face if the
         *  point of intersection with the plane of the face
         *  is inside the face.
         */
                                                /* compute dist. to plane */
        rdot = -DOT(r->rdir, f->norm);
        if (rdot <= FTINY && rdot >= -FTINY)    /* ray parallels plane */
                t = FHUGE;
        else
                t = (DOT(r->rorg, f->norm) - f->offset) / rdot;
        
        if (t <= FTINY || t >= r->rot)          /* not good enough */
                return(0);
                                                /* compute intersection */
        for (i = 0; i < 3; i++)
                pisect[i] = r->rorg[i] + r->rdir[i]*t;

        if (!inface(pisect, f))                 /* ray intersects face? */
                return(0);

        r->ro = o;
        r->rot = t;
        VCOPY(r->rop, pisect);
        VCOPY(r->ron, f->norm);
        r->rod = rdot;
        r->rox = NULL;

        return(1);                              /* hit */
}
Revision:	2.3
Committed:	Tue Feb 25 02:47:23 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.2:	+1 -56 lines
Log Message:	Replaced inline copyright notice with #include "copyright.h"
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.2	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5			* o_face.c - compute ray intersection with faces.
6	greg	2.2	*/
7
8	greg	2.3	#include "copyright.h"
9	greg	1.1
10			#include "ray.h"
11
12			#include "face.h"
13
14
15			o_face(o, r) /* compute intersection with polygonal face */
16			OBJREC *o;
17			register RAY *r;
18			{
19			double rdot; /* direction . normal */
20			double t; /* distance to intersection */
21			FVECT pisect; /* intersection point */
22			register FACE f; / face record */
23			register int i;
24
25			f = getface(o);
26
27			/*
28			* First, we find the distance to the plane containing the
29			* face. If this distance is less than zero or greater
30			* than a previous intersection, we return. Otherwise,
31			* we determine whether in fact the ray intersects the
32			* face. The ray intersects the face if the
33			* point of intersection with the plane of the face
34			* is inside the face.
35			*/
36			/* compute dist. to plane */
37			rdot = -DOT(r->rdir, f->norm);
38			if (rdot <= FTINY && rdot >= -FTINY) /* ray parallels plane */
39			t = FHUGE;
40			else
41	greg	1.2	t = (DOT(r->rorg, f->norm) - f->offset) / rdot;
42	greg	1.1
43			if (t <= FTINY \|\| t >= r->rot) /* not good enough */
44			return(0);
45			/* compute intersection */
46			for (i = 0; i < 3; i++)
47			pisect[i] = r->rorg[i] + r->rdir[i]*t;
48
49	greg	1.3	if (!inface(pisect, f)) /* ray intersects face? */
50			return(0);
51	greg	1.1
52	greg	1.3	r->ro = o;
53			r->rot = t;
54			VCOPY(r->rop, pisect);
55			VCOPY(r->ron, f->norm);
56			r->rod = rdot;
57	greg	1.4	r->rox = NULL;
58	greg	1.3
59	greg	1.1	return(1); /* hit */
60			}