src/ot/o_instance.c

#ifndef lint
static const char RCSid[] = "$Id: o_instance.c,v 2.3 2003/03/11 17:08:55 greg Exp $";
#endif
/*
 *  o_instance.c - routines for creating octrees for other octrees
 */

#include  "standard.h"

#include  "object.h"

#include  "octree.h"

#include  "instance.h"

#include  "mesh.h"

#include  "plocate.h"

/*
 *      To determine if two cubes intersect:
 *
 *      1) Check to see if any vertices of first cube are inside the
 *         second (intersection).
 *
 *      2) Check to see if all vertices of first are to one side of
 *         second (no intersection).
 *
 *      3) Perform 1 and 2 with roles reversed.
 *
 *      4) Check to see if any portion of any edge of second is inside
 *         first (intersection).
 *
 *      5) If test 4 fails, we have no intersection.
 *
 *      Note that if we were testing two boxes, we would need
 *  to check that neither had any edges inside the other to be sure.
 *      Since an octree is a volume rather than a surface, we will
 *  return a value of 2 if the cube is entirely within the octree.
 */


static int
o_cube(cu1, fxf, cu)                    /* determine if cubes intersect */
CUBE  *cu1;
FULLXF  *fxf;
CUBE  *cu;
{
        static int  vstart[4] = {0, 3, 5, 6};
        FVECT  cumin, cumax;
        FVECT  vert[8];
        FVECT  v1, v2;
        int  vloc, vout;
        register int  i, j;
                                        /* check if cube vertex in octree */
        for (j = 0; j < 3; j++)
                cumax[j] = (cumin[j] = cu1->cuorg[j]) + cu1->cusize;
        vloc = ABOVE | BELOW;
        vout = 0;
        for (i = 0; i < 8; i++) {
                for (j = 0; j < 3; j++) {
                        v1[j] = cu->cuorg[j];
                        if (i & 1<<j)
                                v1[j] += cu->cusize;
                }
                multp3(v2, v1, fxf->b.xfm);
                if ( (j = plocate(v2, cumin, cumax)) )
                        vout++;
                vloc &= j;
        }
        if (vout == 0)                  /* all inside */
                return(O_IN);
        if (vout < 8)                   /* some inside */
                return(O_HIT);
        if (vloc)                       /* all to one side */
                return(O_MISS);
                                        /* octree vertices in cube? */
        for (j = 0; j < 3; j++)
                cumax[j] = (cumin[j] = cu->cuorg[j]) + cu->cusize;
        vloc = ABOVE | BELOW;
        for (i = 0; i < 8; i++) {
                for (j = 0; j < 3; j++) {
                        v1[j] = cu1->cuorg[j];
                        if (i & 1<<j)
                                v1[j] += cu1->cusize;
                }
                multp3(vert[i], v1, fxf->f.xfm);
                if ( (j = plocate(vert[i], cumin, cumax)) )
                        vloc &= j;
                else
                        return(O_HIT);  /* vertex inside */
        }
        if (vloc)                       /* all to one side */
                return(O_MISS);
                                        /* check edges */
        for (i = 0; i < 4; i++)
                for (j = 0; j < 3; j++) {
                                                /* clip modifies vertices! */
                        VCOPY(v1, vert[vstart[i]]);
                        VCOPY(v2, vert[vstart[i] ^ 1<<j]);
                        if (clip(v1, v2, cumin, cumax))
                                return(O_HIT);          /* edge inside */
                }

        return(O_MISS);                 /* no intersection */
}


int
o_instance(o, cu)                       /* determine if instance intersects */
OBJREC  *o;
CUBE  *cu;
{
        INSTANCE  *ins;
                                        /* get octree bounds */
        ins = getinstance(o, IO_BOUNDS);
                                        /* call o_cube to do the work */
        return(o_cube(&ins->obj->scube, &ins->x, cu));
}


int
o_mesh(o, cu)                           /* determine if mesh intersects */
OBJREC  *o;
CUBE  *cu;
{
        MESHINST        *mip;
                                        /* get mesh bounds */
        mip = getmeshinst(o, IO_BOUNDS);
                                        /* call o_cube to do the work */
        return(o_cube(&mip->msh->mcube, &mip->x, cu));
}
Revision:	2.4
Committed:	Sun Jul 27 22:12:03 2003 UTC (22 years, 3 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 2.3:	+3 -3 lines
Log Message:	Added grouping parens to reduce ambiguity warnings.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.4	static const char RCSid[] = "$Id: o_instance.c,v 2.3 2003/03/11 17:08:55 greg Exp $";
3	greg	1.1	#endif
4			/*
5	greg	2.3	* o_instance.c - routines for creating octrees for other octrees
6	greg	1.1	*/
7
8			#include "standard.h"
9
10			#include "object.h"
11	greg	2.2
12			#include "octree.h"
13	greg	1.1
14			#include "instance.h"
15
16	greg	2.3	#include "mesh.h"
17
18	greg	1.1	#include "plocate.h"
19
20			/*
21			* To determine if two cubes intersect:
22			*
23			* 1) Check to see if any vertices of first cube are inside the
24			* second (intersection).
25			*
26			* 2) Check to see if all vertices of first are to one side of
27			* second (no intersection).
28			*
29			* 3) Perform 1 and 2 with roles reversed.
30			*
31			* 4) Check to see if any portion of any edge of second is inside
32			* first (intersection).
33			*
34			* 5) If test 4 fails, we have no intersection.
35			*
36			* Note that if we were testing two boxes, we would need
37			* to check that neither had any edges inside the other to be sure.
38			* Since an octree is a volume rather than a surface, we will
39			* return a value of 2 if the cube is entirely within the octree.
40			*/
41
42
43	greg	2.3	static int
44			o_cube(cu1, fxf, cu) /* determine if cubes intersect */
45			CUBE *cu1;
46			FULLXF *fxf;
47	greg	1.1	CUBE *cu;
48			{
49	greg	1.2	static int vstart[4] = {0, 3, 5, 6};
50	greg	1.1	FVECT cumin, cumax;
51			FVECT vert[8];
52			FVECT v1, v2;
53			int vloc, vout;
54			register int i, j;
55			/* check if cube vertex in octree */
56			for (j = 0; j < 3; j++)
57	greg	2.3	cumax[j] = (cumin[j] = cu1->cuorg[j]) + cu1->cusize;
58	greg	1.1	vloc = ABOVE \| BELOW;
59			vout = 0;
60			for (i = 0; i < 8; i++) {
61			for (j = 0; j < 3; j++) {
62			v1[j] = cu->cuorg[j];
63			if (i & 1<<j)
64			v1[j] += cu->cusize;
65			}
66	greg	2.3	multp3(v2, v1, fxf->b.xfm);
67	schorsch	2.4	if ( (j = plocate(v2, cumin, cumax)) )
68	greg	1.1	vout++;
69			vloc &= j;
70			}
71			if (vout == 0) /* all inside */
72	greg	1.3	return(O_IN);
73	greg	1.1	if (vout < 8) /* some inside */
74	greg	1.3	return(O_HIT);
75	greg	1.1	if (vloc) /* all to one side */
76	greg	1.3	return(O_MISS);
77	greg	1.1	/* octree vertices in cube? */
78			for (j = 0; j < 3; j++)
79			cumax[j] = (cumin[j] = cu->cuorg[j]) + cu->cusize;
80			vloc = ABOVE \| BELOW;
81			for (i = 0; i < 8; i++) {
82			for (j = 0; j < 3; j++) {
83	greg	2.3	v1[j] = cu1->cuorg[j];
84	greg	1.1	if (i & 1<<j)
85	greg	2.3	v1[j] += cu1->cusize;
86	greg	1.1	}
87	greg	2.3	multp3(vert[i], v1, fxf->f.xfm);
88	schorsch	2.4	if ( (j = plocate(vert[i], cumin, cumax)) )
89	greg	1.1	vloc &= j;
90			else
91	greg	1.3	return(O_HIT); /* vertex inside */
92	greg	1.1	}
93			if (vloc) /* all to one side */
94	greg	1.3	return(O_MISS);
95	greg	1.1	/* check edges */
96			for (i = 0; i < 4; i++)
97			for (j = 0; j < 3; j++) {
98			/* clip modifies vertices! */
99			VCOPY(v1, vert[vstart[i]]);
100			VCOPY(v2, vert[vstart[i] ^ 1<<j]);
101			if (clip(v1, v2, cumin, cumax))
102	greg	1.3	return(O_HIT); /* edge inside */
103	greg	1.1	}
104
105	greg	1.3	return(O_MISS); /* no intersection */
106	greg	2.3	}
107
108
109			int
110			o_instance(o, cu) /* determine if instance intersects */
111			OBJREC *o;
112			CUBE *cu;
113			{
114			INSTANCE *ins;
115			/* get octree bounds */
116			ins = getinstance(o, IO_BOUNDS);
117			/* call o_cube to do the work */
118			return(o_cube(&ins->obj->scube, &ins->x, cu));
119			}
120
121
122			int
123			o_mesh(o, cu) /* determine if mesh intersects */
124			OBJREC *o;
125			CUBE *cu;
126			{
127			MESHINST *mip;
128			/* get mesh bounds */
129			mip = getmeshinst(o, IO_BOUNDS);
130			/* call o_cube to do the work */
131			return(o_cube(&mip->msh->mcube, &mip->x, cu));
132	greg	1.1	}