src/rt/o_face.c

/* Copyright (c) 1990 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  o_face.c - compute ray intersection with faces.
 *
 *     8/29/85
 */

#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:	2.1
Committed:	Tue Nov 12 17:09:17 1991 UTC (32 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.4:	+0 -0 lines
Log Message:	updated revision number for release 2.0
#	User	Rev	Content
1	greg	1.4	/* Copyright (c) 1990 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* o_face.c - compute ray intersection with faces.
9			*
10			* 8/29/85
11			*/
12
13			#include "ray.h"
14
15			#include "face.h"
16
17
18			o_face(o, r) /* compute intersection with polygonal face */
19			OBJREC *o;
20			register RAY *r;
21			{
22			double rdot; /* direction . normal */
23			double t; /* distance to intersection */
24			FVECT pisect; /* intersection point */
25			register FACE f; / face record */
26			register int i;
27
28			f = getface(o);
29
30			/*
31			* First, we find the distance to the plane containing the
32			* face. If this distance is less than zero or greater
33			* than a previous intersection, we return. Otherwise,
34			* we determine whether in fact the ray intersects the
35			* face. The ray intersects the face if the
36			* point of intersection with the plane of the face
37			* is inside the face.
38			*/
39			/* compute dist. to plane */
40			rdot = -DOT(r->rdir, f->norm);
41			if (rdot <= FTINY && rdot >= -FTINY) /* ray parallels plane */
42			t = FHUGE;
43			else
44	greg	1.2	t = (DOT(r->rorg, f->norm) - f->offset) / rdot;
45	greg	1.1
46			if (t <= FTINY \|\| t >= r->rot) /* not good enough */
47			return(0);
48			/* compute intersection */
49			for (i = 0; i < 3; i++)
50			pisect[i] = r->rorg[i] + r->rdir[i]*t;
51
52	greg	1.3	if (!inface(pisect, f)) /* ray intersects face? */
53			return(0);
54	greg	1.1
55	greg	1.3	r->ro = o;
56			r->rot = t;
57			VCOPY(r->rop, pisect);
58			VCOPY(r->ron, f->norm);
59			r->rod = rdot;
60	greg	1.4	r->rox = NULL;
61	greg	1.3
62	greg	1.1	return(1); /* hit */
63			}