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root/radiance/ray/src/hd/rhdisp3.c
Revision: 3.7
Committed: Wed Nov 26 20:12:19 1997 UTC (26 years, 4 months ago) by gregl
Content type: text/plain
Branch: MAIN
Changes since 3.6: +28 -13 lines
Log Message:
fixed bug in gridlines()

File Contents

# User Rev Content
1 gregl 3.1 /* Copyright (c) 1997 Silicon Graphics, Inc. */
2    
3     #ifndef lint
4     static char SCCSid[] = "$SunId$ SGI";
5     #endif
6    
7     /*
8 gregl 3.2 * Holodeck beam support for display process
9 gregl 3.1 */
10    
11     #include "rholo.h"
12     #include "rhdisp.h"
13     #include "view.h"
14    
15 gregl 3.4 struct cellist {
16     GCOORD *cl;
17     int n;
18     };
19 gregl 3.1
20 gregl 3.4
21 gregl 3.1 int
22     npixels(vp, hr, vr, hp, bi) /* compute appropriate number to evaluate */
23 gregl 3.5 register VIEW *vp;
24 gregl 3.1 int hr, vr;
25     HOLO *hp;
26     int bi;
27     {
28 gregl 3.5 VIEW vrev;
29 gregl 3.1 GCOORD gc[2];
30 gregl 3.5 FVECT cp[4], ip[4];
31     double af, ab;
32 gregl 3.1 register int i;
33     /* compute cell corners in image */
34     if (!hdbcoord(gc, hp, bi))
35     error(CONSISTENCY, "bad beam index in npixels");
36 gregl 3.5 hdcell(cp, hp, gc+1); /* find cell on front image */
37     for (i = 0; i < 4; i++) {
38     viewloc(ip[i], vp, cp[i]);
39     if (ip[i][2] < 0.) {
40     af = 0;
41     goto getback;
42 gregl 3.4 }
43 gregl 3.5 ip[i][0] *= (double)hr; /* scale by resolution */
44     ip[i][1] *= (double)vr;
45 gregl 3.4 }
46 gregl 3.5 /* compute front area */
47     af = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
48     (ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
49     af += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
50     (ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
51     if (af >= 0) af *= 0.5;
52     else af *= -0.5;
53     getback:
54     copystruct(&vrev, vp); /* compute reverse view */
55     for (i = 0; i < 3; i++) {
56     vrev.vdir[i] = -vp->vdir[i];
57     vrev.vup[i] = -vp->vup[i];
58     vrev.hvec[i] = -vp->hvec[i];
59     vrev.vvec[i] = -vp->vvec[i];
60     }
61     hdcell(cp, hp, gc); /* find cell on back image */
62 gregl 3.1 for (i = 0; i < 4; i++) {
63 gregl 3.5 viewloc(ip[i], &vrev, cp[i]);
64 gregl 3.1 if (ip[i][2] < 0.)
65 gregl 3.5 return((int)(af + 0.5));
66 gregl 3.1 ip[i][0] *= (double)hr; /* scale by resolution */
67     ip[i][1] *= (double)vr;
68     }
69 gregl 3.5 /* compute back area */
70     ab = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
71 gregl 3.1 (ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
72 gregl 3.5 ab += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
73 gregl 3.1 (ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
74 gregl 3.5 if (ab >= 0) ab *= 0.5;
75     else ab *= -0.5;
76     /* round off smaller area */
77     if (af <= ab)
78     return((int)(af + 0.5));
79     return((int)(ab + 0.5));
80 gregl 3.1 }
81    
82    
83     /*
84     * The ray directions that define the pyramid in visit_cells() needn't
85     * be normalized, but they must be given in clockwise order as seen
86     * from the pyramid's apex (origin).
87     */
88     int
89     visit_cells(orig, pyrd, hp, vf, dp) /* visit cells within a pyramid */
90     FVECT orig, pyrd[4]; /* pyramid ray directions in clockwise order */
91     HOLO *hp;
92     int (*vf)();
93     char *dp;
94     {
95     int n = 0;
96     int inflags = 0;
97     FVECT gp, pn[4], lo, ld;
98     double po[4], lbeg, lend, d, t;
99     GCOORD gc;
100     register int i;
101     /* figure out whose side we're on */
102     hdgrid(gp, hp, orig);
103     for (i = 0; i < 3; i++) {
104     inflags |= (gp[i] > FTINY) << (i<<1);
105     inflags |= (gp[i] < hp->grid[i]-FTINY) << (i<<1 | 1);
106     }
107     /* compute pyramid planes */
108     for (i = 0; i < 4; i++) {
109     fcross(pn[i], pyrd[i], pyrd[(i+1)&03]);
110     po[i] = DOT(pn[i], orig);
111     }
112     /* traverse each wall */
113     for (gc.w = 0; gc.w < 6; gc.w++) {
114     if (!(inflags & 1<<gc.w)) /* origin on wrong side */
115     continue;
116     /* scanline algorithm */
117     for (gc.i[1] = hp->grid[((gc.w>>1)+2)%3]; gc.i[1]--; ) {
118     /* compute scanline */
119     gp[gc.w>>1] = gc.w&1 ? hp->grid[gc.w>>1] : 0;
120     gp[((gc.w>>1)+1)%3] = 0;
121     gp[((gc.w>>1)+2)%3] = gc.i[1] + 0.5;
122     hdworld(lo, hp, gp);
123     gp[((gc.w>>1)+1)%3] = 1;
124     hdworld(ld, hp, gp);
125 gregl 3.2 ld[0] -= lo[0]; ld[1] -= lo[1]; ld[2] -= lo[2];
126 gregl 3.1 /* find scanline limits */
127     lbeg = 0; lend = hp->grid[((gc.w>>1)+1)%3];
128     for (i = 0; i < 4; i++) {
129     t = DOT(pn[i], lo) - po[i];
130     d = -DOT(pn[i], ld);
131 gregl 3.2 if (d > FTINY) { /* <- plane */
132 gregl 3.1 if ((t /= d) < lend)
133     lend = t;
134 gregl 3.2 } else if (d < -FTINY) { /* plane -> */
135 gregl 3.1 if ((t /= d) > lbeg)
136     lbeg = t;
137 gregl 3.3 } else if (t < 0) { /* outside */
138     lend = -1;
139     break;
140     }
141 gregl 3.1 }
142 gregl 3.3 if (lbeg >= lend)
143     continue;
144 gregl 3.1 i = lend + .5; /* visit cells on this scan */
145     for (gc.i[0] = lbeg + .5; gc.i[0] < i; gc.i[0]++)
146     n += (*vf)(&gc, dp);
147     }
148     }
149     return(n);
150     }
151    
152    
153 gregl 3.4 sect_behind(hp, vp) /* check if section is "behind" viewpoint */
154     register HOLO *hp;
155     register VIEW *vp;
156     {
157     FVECT hcent;
158     /* compute holodeck section center */
159     VSUM(hcent, hp->orig, hp->xv[0], 0.5);
160     VSUM(hcent, hcent, hp->xv[1], 0.5);
161     VSUM(hcent, hcent, hp->xv[2], 0.5);
162     /* behind if center is behind */
163     return(DOT(vp->vdir,hcent) < DOT(vp->vdir,vp->vp));
164     }
165    
166    
167     viewpyramid(org, dir, hp, vp) /* compute view pyramid */
168     FVECT org, dir[4];
169     HOLO *hp;
170     VIEW *vp;
171     {
172     register int i;
173     /* check view type */
174     if (vp->type == VT_PAR)
175     return(0);
176     /* in front or behind? */
177     if (!sect_behind(hp, vp)) {
178     if (viewray(org, dir[0], vp, 0., 0.) < -FTINY)
179     return(0);
180     if (viewray(org, dir[1], vp, 0., 1.) < -FTINY)
181     return(0);
182     if (viewray(org, dir[2], vp, 1., 1.) < -FTINY)
183     return(0);
184     if (viewray(org, dir[3], vp, 1., 0.) < -FTINY)
185     return(0);
186     return(1);
187     } /* reverse pyramid */
188     if (viewray(org, dir[3], vp, 0., 0.) < -FTINY)
189     return(0);
190     if (viewray(org, dir[2], vp, 0., 1.) < -FTINY)
191     return(0);
192     if (viewray(org, dir[1], vp, 1., 1.) < -FTINY)
193     return(0);
194     if (viewray(org, dir[0], vp, 1., 0.) < -FTINY)
195     return(0);
196     for (i = 0; i < 3; i++) {
197     dir[0][i] = -dir[0][i];
198     dir[1][i] = -dir[1][i];
199     dir[2][i] = -dir[2][i];
200     dir[3][i] = -dir[3][i];
201     }
202     return(-1);
203     }
204    
205    
206 gregl 3.1 int
207     addcell(gcp, cl) /* add a cell to a list */
208     GCOORD *gcp;
209 gregl 3.4 register struct cellist *cl;
210 gregl 3.1 {
211 gregl 3.4 copystruct(cl->cl+cl->n, gcp);
212     cl->n++;
213 gregl 3.1 return(1);
214     }
215    
216    
217     int
218     cellcmp(gcp1, gcp2) /* visit_cells() cell ordering */
219     register GCOORD *gcp1, *gcp2;
220     {
221     register int c;
222    
223     if ((c = gcp1->w - gcp2->w))
224     return(c);
225     if ((c = gcp2->i[1] - gcp1->i[1])) /* wg1 is reverse-ordered */
226     return(c);
227     return(gcp1->i[0] - gcp2->i[0]);
228     }
229    
230    
231 gregl 3.4 GCOORD *
232     getviewcells(np, hp, vp) /* get ordered cell list for section view */
233     int *np; /* returned number of cells (negative if reversed) */
234 gregl 3.1 register HOLO *hp;
235     VIEW *vp;
236     {
237     FVECT org, dir[4];
238 gregl 3.4 int orient;
239     struct cellist cl;
240 gregl 3.1 /* compute view pyramid */
241 gregl 3.4 *np = 0;
242     orient = viewpyramid(org, dir, hp, vp);
243     if (!orient)
244     return(NULL);
245 gregl 3.1 /* allocate enough list space */
246 gregl 3.4 cl.n = 2*( hp->grid[0]*hp->grid[1] +
247     hp->grid[0]*hp->grid[2] +
248     hp->grid[1]*hp->grid[2] );
249     cl.cl = (GCOORD *)malloc(cl.n*sizeof(GCOORD));
250     if (cl.cl == NULL)
251 gregl 3.1 goto memerr;
252 gregl 3.4 cl.n = 0; /* add cells within pyramid */
253     visit_cells(org, dir, hp, addcell, &cl);
254     if (!cl.n) {
255     free((char *)cl.cl);
256 gregl 3.1 return(NULL);
257     }
258 gregl 3.4 *np = cl.n * orient;
259 gregl 3.1 #if 0
260 gregl 3.2 /* We're just going to free this memory in a moment, and list is
261     * sorted automatically by visit_cells(), so we don't need this.
262     */
263 gregl 3.4 /* optimize memory use */
264     cl.cl = (GCOORD *)realloc((char *)cl.cl, cl.n*sizeof(GCOORD));
265     if (cl.cl == NULL)
266     goto memerr;
267 gregl 3.1 /* sort the list */
268 gregl 3.4 qsort((char *)cl.cl, cl.n, sizeof(GCOORD), cellcmp);
269 gregl 3.1 #endif
270 gregl 3.4 return(cl.cl);
271 gregl 3.1 memerr:
272     error(SYSTEM, "out of memory in getviewcells");
273     }
274 gregl 3.6
275    
276     gridlines(f) /* run through holodeck section grid lines */
277     int (*f)();
278     {
279     register int hd, w, i;
280     int g0, g1;
281 gregl 3.7 FVECT wp[2], mov;
282 gregl 3.6 double d;
283     /* do each wall on each section */
284     for (hd = 0; hdlist[hd] != NULL; hd++)
285     for (w = 0; w < 6; w++) {
286     g0 = ((w>>1)+1)%3;
287     g1 = ((w>>1)+2)%3;
288 gregl 3.7 d = 1.0/hdlist[hd]->grid[g0];
289     mov[0] = d * hdlist[hd]->xv[g0][0];
290     mov[1] = d * hdlist[hd]->xv[g0][1];
291     mov[2] = d * hdlist[hd]->xv[g0][2];
292     if (w & 1) {
293 gregl 3.6 VSUM(wp[0], hdlist[hd]->orig,
294     hdlist[hd]->xv[w>>1], 1.);
295 gregl 3.7 VSUM(wp[0], wp[0], mov, 1.);
296     } else
297     VCOPY(wp[0], hdlist[hd]->orig);
298     VSUM(wp[1], wp[0], hdlist[hd]->xv[g1], 1.);
299     for (i = hdlist[hd]->grid[g0]; ; ) { /* g0 lines */
300 gregl 3.6 (*f)(wp);
301 gregl 3.7 if (!--i) break;
302     wp[0][0] += mov[0]; wp[0][1] += mov[1];
303     wp[0][2] += mov[2]; wp[1][0] += mov[0];
304     wp[1][1] += mov[1]; wp[1][2] += mov[2];
305 gregl 3.6 }
306 gregl 3.7 d = 1.0/hdlist[hd]->grid[g1];
307     mov[0] = d * hdlist[hd]->xv[g1][0];
308     mov[1] = d * hdlist[hd]->xv[g1][1];
309     mov[2] = d * hdlist[hd]->xv[g1][2];
310     if (w & 1)
311 gregl 3.6 VSUM(wp[0], hdlist[hd]->orig,
312     hdlist[hd]->xv[w>>1], 1.);
313 gregl 3.7 else
314     VSUM(wp[0], hdlist[hd]->orig, mov, 1.);
315     VSUM(wp[1], wp[0], hdlist[hd]->xv[g0], 1.);
316     for (i = hdlist[hd]->grid[g1]; ; ) { /* g1 lines */
317 gregl 3.6 (*f)(wp);
318 gregl 3.7 if (!--i) break;
319     wp[0][0] += mov[0]; wp[0][1] += mov[1];
320     wp[0][2] += mov[2]; wp[1][0] += mov[0];
321     wp[1][1] += mov[1]; wp[1][2] += mov[2];
322 gregl 3.6 }
323     }
324     }