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root/radiance/ray/src/ot/o_cone.c
Revision: 2.4
Committed: Tue Mar 30 16:13:00 2004 UTC (20 years, 3 months ago) by schorsch
Content type: text/plain
Branch: MAIN
CVS Tags: rad3R6, rad3R6P1
Changes since 2.3: +3 -4 lines
Log Message:
Continued ANSIfication. There are only bits and pieces left now.

File Contents

# User Rev Content
1 greg 1.1 #ifndef lint
2 schorsch 2.4 static const char RCSid[] = "$Id: o_cone.c,v 2.3 2004/03/27 12:41:45 schorsch Exp $";
3 greg 1.1 #endif
4     /*
5     * o_cone.c - routines for intersecting cubes with cones.
6     *
7     * 2/3/86
8     */
9    
10     #include "standard.h"
11     #include "octree.h"
12     #include "object.h"
13     #include "cone.h"
14    
15     #define ROOT3 1.732050808
16    
17     /*
18     * The algorithm used to detect cube intersection with cones is
19     * recursive. First, we approximate the cube to be a sphere. Then
20     * we test for cone intersection with the sphere by testing the
21     * segment of the cone which is nearest the sphere's center.
22     * If the cone has points within the cube's bounding sphere,
23     * we must check for intersection with the cube. This is done with
24     * the 3D line clipper. The same cone segment is used in this test.
25     * If the clip fails, we still cannot be sure there is no intersection,
26     * so we subdivide the cube and recurse.
27     * If none of the sub-cubes intersect, then our cube does not intersect.
28     */
29    
30     extern double mincusize; /* minimum cube size */
31    
32 schorsch 2.3 static double findcseg(FVECT ep0, FVECT ep1, CONE *co, FVECT p);
33    
34 greg 1.1
35 schorsch 2.3
36 schorsch 2.4 extern int
37     o_cone( /* determine if cone intersects cube */
38 schorsch 2.3 OBJREC *o,
39     register CUBE *cu
40     )
41 greg 1.1 {
42     CONE *co;
43     FVECT ep0, ep1;
44 schorsch 2.3 #ifdef STRICT
45 greg 1.1 FVECT cumin, cumax;
46     CUBE cukid;
47 schorsch 2.3 register int j;
48     #endif
49 greg 1.1 double r;
50     FVECT p;
51 schorsch 2.3 register int i;
52 greg 1.1 /* get cone arguments */
53     co = getcone(o, 0);
54     /* get cube center */
55     r = cu->cusize * 0.5;
56     for (i = 0; i < 3; i++)
57     p[i] = cu->cuorg[i] + r;
58     r *= ROOT3; /* bounding radius for cube */
59    
60     if (findcseg(ep0, ep1, co, p) > 0.0) {
61     /* check min. distance to cone */
62     if (dist2lseg(p, ep0, ep1) > (r+FTINY)*(r+FTINY))
63 greg 1.2 return(O_MISS);
64 greg 1.1 #ifdef STRICT
65     /* get cube boundaries */
66     for (i = 0; i < 3; i++)
67     cumax[i] = (cumin[i] = cu->cuorg[i]) + cu->cusize;
68     /* closest segment intersects? */
69     if (clip(ep0, ep1, cumin, cumax))
70 greg 1.2 return(O_HIT);
71 greg 1.1 }
72     /* check sub-cubes */
73     cukid.cusize = cu->cusize * 0.5;
74     if (cukid.cusize < mincusize)
75 greg 1.2 return(O_HIT); /* cube too small */
76 greg 1.1 cukid.cutree = EMPTY;
77    
78     for (j = 0; j < 8; j++) {
79     for (i = 0; i < 3; i++) {
80     cukid.cuorg[i] = cu->cuorg[i];
81     if (1<<i & j)
82     cukid.cuorg[i] += cukid.cusize;
83     }
84     if (o_cone(o, &cukid))
85 greg 1.2 return(O_HIT); /* sub-cube intersects */
86 greg 1.1 }
87 greg 1.2 return(O_MISS); /* no intersection */
88 greg 1.1 #else
89     }
90 greg 1.2 return(O_HIT); /* assume intersection */
91 greg 1.1 #endif
92     }
93    
94    
95 schorsch 2.3 static double
96     findcseg( /* find line segment from cone closest to p */
97     FVECT ep0,
98     FVECT ep1,
99     register CONE *co,
100     FVECT p
101     )
102 greg 1.1 {
103     double d;
104     FVECT v;
105     register int i;
106     /* find direction from axis to point */
107     for (i = 0; i < 3; i++)
108     v[i] = p[i] - CO_P0(co)[i];
109     d = DOT(v, co->ad);
110     for (i = 0; i < 3; i++)
111     v[i] = v[i] - d*co->ad[i];
112     d = normalize(v);
113     if (d > 0.0) /* find endpoints of segment */
114     for (i = 0; i < 3; i++) {
115     ep0[i] = CO_R0(co)*v[i] + CO_P0(co)[i];
116     ep1[i] = CO_R1(co)*v[i] + CO_P1(co)[i];
117     }
118     return(d); /* return distance from axis */
119     }