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/* Copyright (c) 1998 Silicon Graphics, Inc. */
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#ifndef lint
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static char SCCSid[] = "$SunId$ SGI";
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#endif
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/*
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* Holodeck beam tracking for display process
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*/
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#include "rholo.h"
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#include "rhdisp.h"
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#include "rhdriver.h"
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#include "random.h"
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#ifndef MAXDIST
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#define MAXDIST 42 /* maximum distance outside section */
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#endif
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#ifndef NVSAMPS
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#define NVSAMPS 16384 /* number of ray samples per view */
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#endif
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#ifndef MEYERNG
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#define MEYERNG 0.2 /* target mean eye range (rel. to grid) */
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#endif
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#ifndef MAXTODO
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#define MAXTODO 3 /* maximum sections to look at */
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#endif
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#ifndef MAXDRAT
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#define MAXDRAT 3.0 /* maximum distance ratio btwn. cand. sect. */
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#endif
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#define CBEAMBLK 1024 /* cbeam allocation block size */
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static struct beamcomp {
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int hd; /* holodeck section number */
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int bi; /* beam index */
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int4 nr; /* number of samples desired */
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} *cbeam = NULL; /* current beam list */
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VIEWPOINT cureye; /* current eye position */
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static int ncbeams = 0; /* number of sorted beams in cbeam */
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static int xcbeams = 0; /* extra (unregistered) beams past ncbeams */
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static int maxcbeam = 0; /* size of cbeam array */
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int
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newcbeam() /* allocate new entry at end of cbeam array */
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{
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int i;
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if ((i = ncbeams + xcbeams++) >= maxcbeam) { /* grow array */
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maxcbeam += CBEAMBLK;
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if (cbeam == NULL)
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cbeam = (struct beamcomp *)malloc(
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maxcbeam*sizeof(struct beamcomp) );
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else
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cbeam = (struct beamcomp *)realloc( (char *)cbeam,
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maxcbeam*sizeof(struct beamcomp) );
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if (cbeam == NULL)
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error(SYSTEM, "out of memory in newcbeam");
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}
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return(i);
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}
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int
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cbeamcmp(cb1, cb2) /* compare two cbeam entries for sort: keep orphans */
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register struct beamcomp *cb1, *cb2;
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{
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register int c;
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if ((c = cb1->bi - cb2->bi)) /* sort on beam index first */
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return(c);
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return(cb1->hd - cb2->hd); /* use hd to resolve matches */
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}
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int
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cbeamcmp2(cb1, cb2) /* compare two cbeam entries for sort: no orphans */
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register struct beamcomp *cb1, *cb2;
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{
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register int c;
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if (!cb1->nr) /* put orphans at the end, unsorted */
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return(cb2->nr);
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if (!cb2->nr)
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return(-1);
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if ((c = cb1->bi - cb2->bi)) /* sort on beam index first */
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return(c);
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return(cb1->hd - cb2->hd); /* use hd to resolve matches */
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}
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int
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findcbeam(hd, bi) /* find the specified beam in our sorted list */
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int hd, bi;
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{
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struct beamcomp cb;
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register struct beamcomp *p;
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if (ncbeams <= 0)
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return(-1);
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cb.hd = hd; cb.bi = bi; cb.nr = 0;
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p = (struct beamcomp *)bsearch((char *)&cb, (char *)cbeam, ncbeams,
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sizeof(struct beamcomp), cbeamcmp);
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if (p == NULL)
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return(-1);
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return(p - cbeam);
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}
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int
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getcbeam(hd, bi) /* get the specified beam, allocating as necessary */
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register int hd;
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int bi;
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{
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register int n;
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/* first, look in sorted list */
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if ((n = findcbeam(hd, bi)) >= 0)
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return(n);
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/* linear search through xcbeams to be sure */
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for (n = ncbeams+xcbeams; n-- > ncbeams; )
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if (cbeam[n].bi == bi && cbeam[n].hd == hd)
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return(n);
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/* check legality */
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if (hd < 0 | hd >= HDMAX || hdlist[hd] == NULL)
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error(INTERNAL, "illegal holodeck number in getcbeam");
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if (bi < 1 | bi > nbeams(hdlist[hd]))
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error(INTERNAL, "illegal beam index in getcbeam");
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n = newcbeam(); /* allocate and assign */
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cbeam[n].nr = 0; cbeam[n].hd = hd; cbeam[n].bi = bi;
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return(n);
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}
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cbeamsort(adopt) /* sort our beam list, possibly turning out orphans */
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int adopt;
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{
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register int i;
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if (!(ncbeams += xcbeams))
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return;
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xcbeams = 0;
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qsort((char *)cbeam, ncbeams, sizeof(struct beamcomp),
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adopt ? cbeamcmp : cbeamcmp2);
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if (adopt)
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return;
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for (i = ncbeams; i--; ) /* identify orphans */
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if (cbeam[i].nr)
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break;
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xcbeams = ncbeams - ++i; /* put orphans after ncbeams */
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ncbeams = i;
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}
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cbeamop(op, bl, n) /* update beams on server list */
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int op;
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register struct beamcomp *bl;
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int n;
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{
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register PACKHEAD *pa;
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register int i;
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if (n <= 0)
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return;
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pa = (PACKHEAD *)malloc(n*sizeof(PACKHEAD));
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if (pa == NULL)
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error(SYSTEM, "out of memory in cbeamop");
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for (i = 0; i < n; i++) {
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pa[i].hd = bl[i].hd;
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pa[i].bi = bl[i].bi;
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pa[i].nr = bl[i].nr;
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pa[i].nc = 0;
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}
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serv_request(op, n*sizeof(PACKHEAD), (char *)pa);
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free((char *)pa);
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}
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static int
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comptodo(tdl, vw) /* compute holodeck sections in view */
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int tdl[MAXTODO+1];
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VIEW *vw;
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{
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int n = 0;
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FVECT gp, dv;
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double dist2[MAXTODO+1], thisdist2;
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register int i, j;
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/* find closest MAXTODO sections */
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for (i = 0; hdlist[i]; i++) {
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hdgrid(gp, hdlist[i], vw->vp);
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for (j = 0; j < 3; j++)
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if (gp[j] < 0.)
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dv[j] = -gp[j];
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else if (gp[j] > hdlist[i]->grid[j])
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dv[j] = gp[j] - hdlist[i]->grid[j];
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else
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dv[j] = 0.;
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thisdist2 = DOT(dv,dv);
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for (j = n; j > 0 && thisdist2 < dist2[j-1]; j--) {
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tdl[j] = tdl[j-1];
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dist2[j] = dist2[j-1];
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}
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tdl[j] = i;
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dist2[j] = thisdist2;
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if (n < MAXTODO)
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n++;
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}
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/* watch for bad move */
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if (n && dist2[0] > MAXDIST*MAXDIST) {
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error(COMMAND, "move past outer limits");
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return(0);
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}
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/* avoid big differences */
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for (j = 1; j < n; j++)
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if (dist2[j] > MAXDRAT*MAXDRAT*dist2[j-1])
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n = j;
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tdl[n] = -1;
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return(n);
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}
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int
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addview(hd, vw, rad, hres, vres) /* add view for section */
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int hd;
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VIEW *vw;
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double rad;
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int hres, vres;
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{
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int sampquant, samptot = 0;
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int h, v, shr, svr;
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GCOORD gc[2];
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FVECT rorg, rdir;
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/* compute sampling grid */
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if (hres|vres && hres*vres <= NVSAMPS) {
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shr = hres; svr = vres;
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sampquant = 1;
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} else {
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shr = sqrt(NVSAMPS/viewaspect(vw)) + .5;
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svr = (NVSAMPS + shr/2)/shr;
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sampquant = (hres*vres + shr*svr/2)/(shr*svr);
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}
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/* intersect sample rays with section */
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for (v = svr; v--; )
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for (h = shr; h--; ) {
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if (viewray(rorg, rdir, vw, (v+frandom())/svr,
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(h+frandom())/shr) < -FTINY)
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continue;
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if (rad > FTINY) {
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rorg[0] += (1.-2.*frandom())*rad;
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rorg[1] += (1.-2.*frandom())*rad;
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rorg[2] += (1.-2.*frandom())*rad;
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}
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if (hdinter(gc, NULL, NULL, hdlist[hd], rorg, rdir)
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>= 0.99*FHUGE)
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continue;
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cbeam[getcbeam(hd,hdbindex(hdlist[hd],gc))].nr +=
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sampquant;
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samptot += sampquant;
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}
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return(samptot);
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}
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beam_init(fresh) /* clear beam list for new view(s) */
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int fresh;
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{
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register int i;
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if (fresh) /* discard old beams? */
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ncbeams = xcbeams = 0;
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else /* else clear sample requests */
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for (i = ncbeams+xcbeams; i--; )
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cbeam[i].nr = 0;
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cureye.rng = 0.;
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}
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int *
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beam_view(vn, hr, vr) /* add beam view (if advisable) */
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VIEW *vn;
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int hr, vr;
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{
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static int todo[MAXTODO+1];
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int n;
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double er, eravg, d;
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register HOLO *hp;
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register int i;
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/* find nearby sections */
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if (!(n = comptodo(todo, vn)))
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return(NULL);
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/* sort current beam list */
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cbeamsort(1);
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/* add view to nearby sections */
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eravg = 0.;
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for (i = 0; i < n; i++) {
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hp = hdlist[todo[i]];
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if (MEYERNG > FTINY)
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er = MEYERNG/3. / VLEN(hp->wg[0]) +
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MEYERNG/3. / VLEN(hp->wg[1]) +
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MEYERNG/3. / VLEN(hp->wg[2]) ;
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else
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er = 0.;
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if (!addview(todo[i], vn, 0.25*er, hr, vr)) {
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register int j; /* whoops! */
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n--; /* delete from list */
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for (j = i--; j <= n; j++)
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todo[j] = todo[j+1];
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} else
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eravg += er;
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}
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if (eravg <= FTINY)
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return(todo);
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/* compute average eye range */
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eravg /= (double)n;
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/* add to current eye position */
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if (cureye.rng <= FTINY) {
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VCOPY(cureye.vpt, vn->vp);
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cureye.rng = eravg;
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} else if ((d = sqrt(dist2(vn->vp,cureye.vpt))) + eravg > cureye.rng) {
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for (i = 3; i--; )
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cureye.vpt[i] = 0.5*(cureye.vpt[i] + vn->vp[i]);
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cureye.rng = 0.5*(cureye.rng + eravg + d);
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}
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return(todo);
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}
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int
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beam_sync(all) /* update beam list on server */
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int all;
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{
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/* set new eye position */
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serv_request(DR_VIEWPOINT, sizeof(VIEWPOINT), (char *)&cureye);
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/* sort list (put orphans at end) */
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cbeamsort(all < 0);
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/* send beam request */
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if (all)
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cbeamop(DR_NEWSET, cbeam, ncbeams);
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else
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cbeamop(DR_ADJSET, cbeam, ncbeams+xcbeams);
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xcbeams = 0; /* truncate our list */
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return(ncbeams);
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}
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