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root/radiance/ray/src/ot/o_cone.c
Revision: 1.2
Committed: Sat Oct 14 11:19:30 1989 UTC (34 years, 4 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 1.1: +6 -6 lines
Log Message:
Defined return values for intersection functions.
Changed order of call to addobject to rotate O_IN objects.

File Contents

# Content
1 /* Copyright (c) 1986 Regents of the University of California */
2
3 #ifndef lint
4 static char SCCSid[] = "$SunId$ LBL";
5 #endif
6
7 /*
8 * o_cone.c - routines for intersecting cubes with cones.
9 *
10 * 2/3/86
11 */
12
13 #include "standard.h"
14
15 #include "octree.h"
16
17 #include "object.h"
18
19 #include "cone.h"
20
21 #define ROOT3 1.732050808
22
23 /*
24 * The algorithm used to detect cube intersection with cones is
25 * recursive. First, we approximate the cube to be a sphere. Then
26 * we test for cone intersection with the sphere by testing the
27 * segment of the cone which is nearest the sphere's center.
28 * If the cone has points within the cube's bounding sphere,
29 * we must check for intersection with the cube. This is done with
30 * the 3D line clipper. The same cone segment is used in this test.
31 * If the clip fails, we still cannot be sure there is no intersection,
32 * so we subdivide the cube and recurse.
33 * If none of the sub-cubes intersect, then our cube does not intersect.
34 */
35
36 extern double mincusize; /* minimum cube size */
37
38
39 o_cone(o, cu) /* determine if cone intersects cube */
40 OBJREC *o;
41 register CUBE *cu;
42 {
43 double dist2lseg(), findcseg();
44 CONE *co;
45 FVECT ep0, ep1;
46 FVECT cumin, cumax;
47 CUBE cukid;
48 double r;
49 FVECT p;
50 register int i, j;
51 /* get cone arguments */
52 co = getcone(o, 0);
53 /* get cube center */
54 r = cu->cusize * 0.5;
55 for (i = 0; i < 3; i++)
56 p[i] = cu->cuorg[i] + r;
57 r *= ROOT3; /* bounding radius for cube */
58
59 if (findcseg(ep0, ep1, co, p) > 0.0) {
60 /* check min. distance to cone */
61 if (dist2lseg(p, ep0, ep1) > (r+FTINY)*(r+FTINY))
62 return(O_MISS);
63 #ifdef STRICT
64 /* get cube boundaries */
65 for (i = 0; i < 3; i++)
66 cumax[i] = (cumin[i] = cu->cuorg[i]) + cu->cusize;
67 /* closest segment intersects? */
68 if (clip(ep0, ep1, cumin, cumax))
69 return(O_HIT);
70 }
71 /* check sub-cubes */
72 cukid.cusize = cu->cusize * 0.5;
73 if (cukid.cusize < mincusize)
74 return(O_HIT); /* cube too small */
75 cukid.cutree = EMPTY;
76
77 for (j = 0; j < 8; j++) {
78 for (i = 0; i < 3; i++) {
79 cukid.cuorg[i] = cu->cuorg[i];
80 if (1<<i & j)
81 cukid.cuorg[i] += cukid.cusize;
82 }
83 if (o_cone(o, &cukid))
84 return(O_HIT); /* sub-cube intersects */
85 }
86 return(O_MISS); /* no intersection */
87 #else
88 }
89 return(O_HIT); /* assume intersection */
90 #endif
91 }
92
93
94 double
95 findcseg(ep0, ep1, co, p) /* find line segment from cone closest to p */
96 FVECT ep0, ep1;
97 register CONE *co;
98 FVECT p;
99 {
100 double d;
101 FVECT v;
102 register int i;
103 /* find direction from axis to point */
104 for (i = 0; i < 3; i++)
105 v[i] = p[i] - CO_P0(co)[i];
106 d = DOT(v, co->ad);
107 for (i = 0; i < 3; i++)
108 v[i] = v[i] - d*co->ad[i];
109 d = normalize(v);
110 if (d > 0.0) /* find endpoints of segment */
111 for (i = 0; i < 3; i++) {
112 ep0[i] = CO_R0(co)*v[i] + CO_P0(co)[i];
113 ep1[i] = CO_R1(co)*v[i] + CO_P1(co)[i];
114 }
115 return(d); /* return distance from axis */
116 }