ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/radiance/ray/src/ot/o_face.c
Revision: 2.5
Committed: Tue Mar 30 16:13:00 2004 UTC (19 years, 10 months ago) by schorsch
Content type: text/plain
Branch: MAIN
CVS Tags: rad5R4, rad5R2, rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1, rad5R3, HEAD
Changes since 2.4: +2 -3 lines
Log Message:
Continued ANSIfication. There are only bits and pieces left now.

File Contents

# Content
1 #ifndef lint
2 static const char RCSid[] = "$Id: o_face.c,v 2.4 2004/03/27 12:41:45 schorsch Exp $";
3 #endif
4 /*
5 * o_face.c - routines for creating octrees for polygonal faces.
6 *
7 * 8/27/85
8 */
9
10 #include "standard.h"
11
12 #include "octree.h"
13
14 #include "object.h"
15
16 #include "face.h"
17
18 #include "plocate.h"
19
20 /*
21 * The algorithm for determining a face's intersection
22 * with a cube is relatively straightforward:
23 *
24 * 1) Check to see if any vertices are inside the cube
25 * (intersection).
26 *
27 * 2) Check to see if all vertices are to one side of
28 * cube (no intersection).
29 *
30 * 3) Check to see if any portion of any edge is inside
31 * cube (intersection).
32 *
33 * 4) Check to see if the cube cuts the plane of the
34 * face and one of its edges passes through
35 * the face (intersection).
36 *
37 * 5) If test 4 fails, we have no intersection.
38 */
39
40 int
41 o_face( /* determine if face intersects cube */
42 OBJREC *o,
43 CUBE *cu
44 )
45 {
46 FVECT cumin, cumax;
47 FVECT v1, v2;
48 double d1, d2;
49 int vloc;
50 register FACE *f;
51 register int i, j;
52 /* get face arguments */
53 f = getface(o);
54 if (f->area == 0.0) /* empty face */
55 return(O_MISS);
56 /* compute cube boundaries */
57 for (j = 0; j < 3; j++)
58 cumax[j] = (cumin[j] = cu->cuorg[j]-FTINY)
59 + cu->cusize + 2.0*FTINY;
60
61 vloc = ABOVE | BELOW; /* check vertices */
62 for (i = 0; i < f->nv; i++)
63 if ( (j = plocate(VERTEX(f,i), cumin, cumax)) )
64 vloc &= j;
65 else
66 return(O_HIT); /* vertex inside */
67
68 if (vloc) /* all to one side */
69 return(O_MISS);
70
71 for (i = 0; i < f->nv; i++) { /* check edges */
72 if ((j = i + 1) >= f->nv)
73 j = 0; /* wrap around */
74 VCOPY(v1, VERTEX(f,i)); /* clip modifies */
75 VCOPY(v2, VERTEX(f,j)); /* the vertices! */
76 if (clip(v1, v2, cumin, cumax))
77 return(O_HIT); /* edge inside */
78 }
79 /* see if cube cuts plane */
80 for (j = 0; j < 3; j++)
81 if (f->norm[j] > 0.0) {
82 v1[j] = cumin[j];
83 v2[j] = cumax[j];
84 } else {
85 v1[j] = cumax[j];
86 v2[j] = cumin[j];
87 }
88 if ((d1 = DOT(v1, f->norm) - f->offset) > FTINY)
89 return(O_MISS);
90 if ((d2 = DOT(v2, f->norm) - f->offset) < -FTINY)
91 return(O_MISS);
92 /* intersect face */
93 for (j = 0; j < 3; j++)
94 v1[j] = (v1[j]*d2 - v2[j]*d1)/(d2 - d1);
95 if (inface(v1, f))
96 return(O_HIT);
97
98 return(O_MISS); /* no intersection */
99 }