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root/radiance/ray/src/ot/o_instance.c
Revision: 2.4
Committed: Sun Jul 27 22:12:03 2003 UTC (21 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.

File Contents

# Content
1 #ifndef lint
2 static const char RCSid[] = "$Id: o_instance.c,v 2.3 2003/03/11 17:08:55 greg Exp $";
3 #endif
4 /*
5 * o_instance.c - routines for creating octrees for other octrees
6 */
7
8 #include "standard.h"
9
10 #include "object.h"
11
12 #include "octree.h"
13
14 #include "instance.h"
15
16 #include "mesh.h"
17
18 #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 static int
44 o_cube(cu1, fxf, cu) /* determine if cubes intersect */
45 CUBE *cu1;
46 FULLXF *fxf;
47 CUBE *cu;
48 {
49 static int vstart[4] = {0, 3, 5, 6};
50 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 cumax[j] = (cumin[j] = cu1->cuorg[j]) + cu1->cusize;
58 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 multp3(v2, v1, fxf->b.xfm);
67 if ( (j = plocate(v2, cumin, cumax)) )
68 vout++;
69 vloc &= j;
70 }
71 if (vout == 0) /* all inside */
72 return(O_IN);
73 if (vout < 8) /* some inside */
74 return(O_HIT);
75 if (vloc) /* all to one side */
76 return(O_MISS);
77 /* 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 v1[j] = cu1->cuorg[j];
84 if (i & 1<<j)
85 v1[j] += cu1->cusize;
86 }
87 multp3(vert[i], v1, fxf->f.xfm);
88 if ( (j = plocate(vert[i], cumin, cumax)) )
89 vloc &= j;
90 else
91 return(O_HIT); /* vertex inside */
92 }
93 if (vloc) /* all to one side */
94 return(O_MISS);
95 /* 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 return(O_HIT); /* edge inside */
103 }
104
105 return(O_MISS); /* no intersection */
106 }
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 }