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root/radiance/ray/src/hd/rhdisp3.c
Revision: 3.1
Committed: Wed Nov 19 18:01:03 1997 UTC (26 years, 4 months ago) by gregl
Content type: text/plain
Branch: MAIN
Log Message:
Initial revision

File Contents

# Content
1 /* Copyright (c) 1997 Silicon Graphics, Inc. */
2
3 #ifndef lint
4 static char SCCSid[] = "$SunId$ SGI";
5 #endif
6
7 /*
8 * Holodeck beam support
9 */
10
11 #include "rholo.h"
12 #include "rhdisp.h"
13 #include "view.h"
14
15
16 int
17 npixels(vp, hr, vr, hp, bi) /* compute appropriate number to evaluate */
18 VIEW *vp;
19 int hr, vr;
20 HOLO *hp;
21 int bi;
22 {
23 GCOORD gc[2];
24 FVECT cp[4];
25 FVECT ip[4];
26 double d;
27 register int i;
28 /* compute cell corners in image */
29 if (!hdbcoord(gc, hp, bi))
30 error(CONSISTENCY, "bad beam index in npixels");
31 hdcell(cp, hp, gc+1);
32 for (i = 0; i < 4; i++) {
33 viewloc(ip[i], vp, cp[i]);
34 if (ip[i][2] < 0.)
35 return(0);
36 ip[i][0] *= (double)hr; /* scale by resolution */
37 ip[i][1] *= (double)vr;
38 }
39 /* compute quad area */
40 d = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
41 (ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
42 d += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
43 (ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
44 if (d < 0)
45 d = -d;
46 /* round off result */
47 return((int)(.5*d+.5));
48 }
49
50
51 /*
52 * The ray directions that define the pyramid in visit_cells() needn't
53 * be normalized, but they must be given in clockwise order as seen
54 * from the pyramid's apex (origin).
55 */
56 int
57 visit_cells(orig, pyrd, hp, vf, dp) /* visit cells within a pyramid */
58 FVECT orig, pyrd[4]; /* pyramid ray directions in clockwise order */
59 HOLO *hp;
60 int (*vf)();
61 char *dp;
62 {
63 int n = 0;
64 int inflags = 0;
65 FVECT gp, pn[4], lo, ld;
66 double po[4], lbeg, lend, d, t;
67 GCOORD gc;
68 register int i;
69 /* figure out whose side we're on */
70 hdgrid(gp, hp, orig);
71 for (i = 0; i < 3; i++) {
72 inflags |= (gp[i] > FTINY) << (i<<1);
73 inflags |= (gp[i] < hp->grid[i]-FTINY) << (i<<1 | 1);
74 }
75 /* compute pyramid planes */
76 for (i = 0; i < 4; i++) {
77 fcross(pn[i], pyrd[i], pyrd[(i+1)&03]);
78 po[i] = DOT(pn[i], orig);
79 }
80 /* traverse each wall */
81 for (gc.w = 0; gc.w < 6; gc.w++) {
82 if (!(inflags & 1<<gc.w)) /* origin on wrong side */
83 continue;
84 /* scanline algorithm */
85 for (gc.i[1] = hp->grid[((gc.w>>1)+2)%3]; gc.i[1]--; ) {
86 /* compute scanline */
87 gp[gc.w>>1] = gc.w&1 ? hp->grid[gc.w>>1] : 0;
88 gp[((gc.w>>1)+1)%3] = 0;
89 gp[((gc.w>>1)+2)%3] = gc.i[1] + 0.5;
90 hdworld(lo, hp, gp);
91 gp[((gc.w>>1)+1)%3] = 1;
92 hdworld(ld, hp, gp);
93 ld[0] -= lo[0]; ld[1] -= lo[1]; ld[2] -= lo[1];
94 /* find scanline limits */
95 lbeg = 0; lend = hp->grid[((gc.w>>1)+1)%3];
96 for (i = 0; i < 4; i++) {
97 t = DOT(pn[i], lo) - po[i];
98 d = -DOT(pn[i], ld);
99 if (d <= FTINY && d >= -FTINY) {
100 if (t < 0)
101 goto nextscan;
102 continue;
103 }
104 if (t > 0) {
105 if ((t /= d) < lend)
106 lend = t;
107 } else {
108 if ((t /= d) > lbeg)
109 lbeg = t;
110 }
111 }
112 i = lend + .5; /* visit cells on this scan */
113 for (gc.i[0] = lbeg + .5; gc.i[0] < i; gc.i[0]++)
114 n += (*vf)(&gc, dp);
115 nextscan:;
116 }
117 }
118 return(n);
119 }
120
121
122 int
123 addcell(gcp, cl) /* add a cell to a list */
124 GCOORD *gcp;
125 register int *cl;
126 {
127 copystruct((GCOORD *)(cl+1) + *cl, gcp);
128 (*cl)++;
129 return(1);
130 }
131
132
133 int
134 cellcmp(gcp1, gcp2) /* visit_cells() cell ordering */
135 register GCOORD *gcp1, *gcp2;
136 {
137 register int c;
138
139 if ((c = gcp1->w - gcp2->w))
140 return(c);
141 if ((c = gcp2->i[1] - gcp1->i[1])) /* wg1 is reverse-ordered */
142 return(c);
143 return(gcp1->i[0] - gcp2->i[0]);
144 }
145
146
147 int *
148 getviewcells(hp, vp) /* get ordered cell list for section view */
149 register HOLO *hp;
150 VIEW *vp;
151 {
152 FVECT org, dir[4];
153 int n;
154 register int *cl;
155 /* compute view pyramid */
156 if (vp->type == VT_PAR) goto viewerr;
157 if (viewray(org, dir[0], vp, 0., 0.) < -FTINY) goto viewerr;
158 if (viewray(org, dir[1], vp, 0., 1.) < -FTINY) goto viewerr;
159 if (viewray(org, dir[2], vp, 1., 1.) < -FTINY) goto viewerr;
160 if (viewray(org, dir[3], vp, 1., 0.) < -FTINY) goto viewerr;
161 /* allocate enough list space */
162 n = 2*( hp->grid[0]*hp->grid[1] +
163 hp->grid[0]*hp->grid[2] +
164 hp->grid[1]*hp->grid[2] );
165 cl = (int *)malloc(sizeof(int) + n*sizeof(GCOORD));
166 if (cl == NULL)
167 goto memerr;
168 *cl = 0;
169 /* add cells within pyramid */
170 visit_cells(org, dir, hp, addcell, cl);
171 if (!*cl) {
172 free((char *)cl);
173 return(NULL);
174 }
175 #if 0
176 /* We're just going to free this memory in a moment, and list is */
177 /* sorted automatically by visit_cells(), so we don't need this. */
178 if (*cl < n) { /* optimize memory use */
179 cl = (int *)realloc((char *)cl,
180 sizeof(int) + *cl*sizeof(GCOORD));
181 if (cl == NULL)
182 goto memerr;
183 }
184 /* sort the list */
185 qsort((char *)(cl+1), *cl, sizeof(GCOORD), cellcmp);
186 #endif
187 return(cl);
188 viewerr:
189 error(INTERNAL, "unusable view in getviewcells");
190 memerr:
191 error(SYSTEM, "out of memory in getviewcells");
192 }