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#ifndef lint
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static const char RCSid[] = "$Id: rhdisp3.c,v 3.17 2018/01/24 04:39:52 greg Exp $";
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#endif
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/*
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* Holodeck beam support 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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struct cellist {
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GCOORD *cl;
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int n;
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};
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int
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npixels(vp, hr, vr, hp, bi) /* compute appropriate nrays to evaluate */
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VIEW *vp;
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int hr, vr;
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HOLO *hp;
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int bi;
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{
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VIEW vrev;
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GCOORD gc[2];
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FVECT cp[4], ip[4], pf, pb;
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double af, ab, sf2, sb2, dfb2, df2, db2, penalty;
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int i;
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/* special case */
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if (hr <= 0 | vr <= 0)
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return(0);
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/* compute cell corners in image */
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if (!hdbcoord(gc, hp, bi))
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error(CONSISTENCY, "bad beam index in npixels");
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hdcell(cp, hp, gc+1); /* find cell on front image */
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for (i = 3; i--; ) /* compute front center */
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pf[i] = 0.5*(cp[0][i] + cp[2][i]);
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sf2 = 0.25*dist2(cp[0], cp[2]); /* compute half diagonal length */
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for (i = 0; i < 4; i++) { /* compute visible quad */
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if (viewloc(ip[i], vp, cp[i]) <= 0) {
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af = 0;
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goto getback;
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}
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ip[i][0] *= (double)hr; /* scale by resolution */
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ip[i][1] *= (double)vr;
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}
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/* compute front area */
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af = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
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(ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
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af += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
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(ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
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af *= af >= 0 ? 0.5 : -0.5;
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getback:
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vrev = *vp; /* compute reverse view */
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for (i = 0; i < 3; i++) {
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vrev.vdir[i] = -vp->vdir[i];
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vrev.vup[i] = -vp->vup[i];
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vrev.hvec[i] = -vp->hvec[i];
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vrev.vvec[i] = -vp->vvec[i];
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}
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hdcell(cp, hp, gc); /* find cell on back image */
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for (i = 3; i--; ) /* compute rear center */
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pb[i] = 0.5*(cp[0][i] + cp[2][i]);
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sb2 = 0.25*dist2(cp[0], cp[2]); /* compute half diagonal length */
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for (i = 0; i < 4; i++) { /* compute visible quad */
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if (viewloc(ip[i], &vrev, cp[i]) <= 0) {
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ab = 0;
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goto finish;
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}
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ip[i][0] *= (double)hr; /* scale by resolution */
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ip[i][1] *= (double)vr;
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}
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/* compute back area */
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ab = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
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(ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
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ab += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
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(ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
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ab *= ab >= 0 ? 0.5 : -0.5;
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finish: /* compute penalty based on dist. sightline - viewpoint */
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df2 = dist2(vp->vp, pf);
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db2 = dist2(vp->vp, pb);
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dfb2 = dist2(pf, pb);
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penalty = dfb2 + df2 - db2;
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penalty = df2 - 0.25*penalty*penalty/dfb2;
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if (df2 > db2) penalty /= df2 <= dfb2 ? sb2 : sb2*df2/dfb2;
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else penalty /= db2 <= dfb2 ? sf2 : sf2*db2/dfb2;
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if (penalty < 1.) penalty = 1.;
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/* round off smaller non-zero area */
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if (ab <= FTINY || (af > FTINY && af <= ab))
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return((int)(af/penalty + 0.5));
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return((int)(ab/penalty + 0.5));
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}
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/*
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* The ray directions that define the pyramid in visit_cells() needn't
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* be normalized, but they must be given in clockwise order as seen
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* from the pyramid's apex (origin).
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* If no cell centers fall within the domain, the closest cell is visited.
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*/
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int
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visit_cells(orig, pyrd, hp, vf, dp) /* visit cells within a pyramid */
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FVECT orig, pyrd[4]; /* pyramid ray directions in clockwise order */
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HOLO *hp;
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int (*vf)();
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char *dp;
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{
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int ncalls = 0, n = 0;
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int inflags = 0;
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FVECT gp, pn[4], lo, ld;
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double po[4], lbeg, lend, d, t;
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GCOORD gc, gc2[2];
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int i;
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/* figure out whose side we're on */
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hdgrid(gp, hp, orig);
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for (i = 0; i < 3; i++) {
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inflags |= (gp[i] > FTINY) << (i<<1);
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inflags |= (gp[i] < hp->grid[i]-FTINY) << (i<<1 | 1);
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}
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/* compute pyramid planes */
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for (i = 0; i < 4; i++) {
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fcross(pn[i], pyrd[i], pyrd[(i+1)&03]);
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po[i] = DOT(pn[i], orig);
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}
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/* traverse each wall */
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for (gc.w = 0; gc.w < 6; gc.w++) {
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if (!(inflags & 1<<gc.w)) /* origin on wrong side */
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continue;
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/* scanline algorithm */
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for (gc.i[1] = hp->grid[hdwg1[gc.w]]; gc.i[1]--; ) {
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/* compute scanline */
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gp[gc.w>>1] = gc.w&1 ? hp->grid[gc.w>>1] : 0;
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gp[hdwg0[gc.w]] = 0;
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gp[hdwg1[gc.w]] = gc.i[1] + 0.5;
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hdworld(lo, hp, gp);
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gp[hdwg0[gc.w]] = 1;
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hdworld(ld, hp, gp);
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ld[0] -= lo[0]; ld[1] -= lo[1]; ld[2] -= lo[2];
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/* find scanline limits */
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lbeg = 0; lend = hp->grid[hdwg0[gc.w]];
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for (i = 0; i < 4; i++) {
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t = DOT(pn[i], lo) - po[i];
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d = -DOT(pn[i], ld);
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if (d > FTINY) { /* <- plane */
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if ((t /= d) < lend)
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lend = t;
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} else if (d < -FTINY) { /* plane -> */
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if ((t /= d) > lbeg)
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lbeg = t;
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} else if (t < 0) { /* outside */
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lend = -1;
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break;
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}
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}
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if (lbeg >= lend)
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continue;
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i = lend + .5; /* visit cells on this scan */
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for (gc.i[0] = lbeg + .5; gc.i[0] < i; gc.i[0]++) {
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n += (*vf)(&gc, dp);
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ncalls++;
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}
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}
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}
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if (ncalls) /* got one at least */
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return(n);
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/* else find closest cell */
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VSUM(ld, pyrd[0], pyrd[1], 1.);
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VSUM(ld, ld, pyrd[2], 1.);
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VSUM(ld, ld, pyrd[3], 1.);
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#if 0
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if (normalize(ld) == 0.0) /* technically not necessary */
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return(0);
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#endif
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d = hdinter(gc2, NULL, &t, hp, orig, ld);
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if (d >= FHUGE || t <= 0.)
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return(0);
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return((*vf)(gc2+1, dp)); /* visit it */
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}
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sect_behind(hp, vp) /* check if section is "behind" viewpoint */
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HOLO *hp;
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VIEW *vp;
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{
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FVECT hcent;
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/* compute holodeck section center */
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VSUM(hcent, hp->orig, hp->xv[0], 0.5);
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VSUM(hcent, hcent, hp->xv[1], 0.5);
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VSUM(hcent, hcent, hp->xv[2], 0.5);
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/* behind if center is behind */
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return(DOT(vp->vdir,hcent) < DOT(vp->vdir,vp->vp));
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}
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viewpyramid(org, dir, hp, vp) /* compute view pyramid */
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FVECT org, dir[4];
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HOLO *hp;
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VIEW *vp;
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{
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int i;
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/* check view type */
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if (vp->type == VT_PAR)
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return(0);
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/* in front or behind? */
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if (!sect_behind(hp, vp)) {
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if (viewray(org, dir[0], vp, 0., 0.) < -FTINY)
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return(0);
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if (viewray(org, dir[1], vp, 0., 1.) < -FTINY)
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return(0);
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if (viewray(org, dir[2], vp, 1., 1.) < -FTINY)
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return(0);
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if (viewray(org, dir[3], vp, 1., 0.) < -FTINY)
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return(0);
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return(1);
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} /* reverse pyramid */
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if (viewray(org, dir[3], vp, 0., 0.) < -FTINY)
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return(0);
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if (viewray(org, dir[2], vp, 0., 1.) < -FTINY)
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return(0);
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if (viewray(org, dir[1], vp, 1., 1.) < -FTINY)
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return(0);
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if (viewray(org, dir[0], vp, 1., 0.) < -FTINY)
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return(0);
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for (i = 0; i < 3; i++) {
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dir[0][i] = -dir[0][i];
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dir[1][i] = -dir[1][i];
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dir[2][i] = -dir[2][i];
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dir[3][i] = -dir[3][i];
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}
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return(-1);
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}
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int
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addcell(gcp, cl) /* add a cell to a list */
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GCOORD *gcp;
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struct cellist *cl;
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{
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*(cl->cl+cl->n) = *gcp;
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cl->n++;
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return(1);
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}
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int
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cellcmp(gcp1, gcp2) /* visit_cells() cell ordering */
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GCOORD *gcp1, *gcp2;
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{
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int c;
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if ((c = gcp1->w - gcp2->w))
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return(c);
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if ((c = gcp2->i[1] - gcp1->i[1])) /* wg1 is reverse-ordered */
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return(c);
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return(gcp1->i[0] - gcp2->i[0]);
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}
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GCOORD *
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getviewcells(np, hp, vp) /* get ordered cell list for section view */
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int *np; /* returned number of cells (negative if reversed) */
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HOLO *hp;
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VIEW *vp;
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{
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FVECT org, dir[4];
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int orient;
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struct cellist cl;
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/* compute view pyramid */
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*np = 0;
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orient = viewpyramid(org, dir, hp, vp);
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if (!orient)
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return(NULL);
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/* allocate enough list space */
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cl.n = 2*( hp->grid[0]*hp->grid[1] +
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hp->grid[0]*hp->grid[2] +
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hp->grid[1]*hp->grid[2] );
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cl.cl = (GCOORD *)malloc(cl.n*sizeof(GCOORD));
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if (cl.cl == NULL)
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goto memerr;
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cl.n = 0; /* add cells within pyramid */
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visit_cells(org, dir, hp, addcell, (char *)&cl);
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if (!cl.n) {
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free((void *)cl.cl);
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return(NULL);
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}
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*np = cl.n * orient;
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#if 0
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/* We're just going to free this memory in a moment, and list is
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* sorted automatically by visit_cells(), so we don't need this.
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*/
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/* optimize memory use */
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cl.cl = (GCOORD *)realloc((void *)cl.cl, cl.n*sizeof(GCOORD));
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if (cl.cl == NULL)
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goto memerr;
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/* sort the list */
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qsort((char *)cl.cl, cl.n, sizeof(GCOORD), cellcmp);
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#endif
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return(cl.cl);
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memerr:
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error(SYSTEM, "out of memory in getviewcells");
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}
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void
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gridlines( /* run through holodeck section grid lines */
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void (*f)(FVECT wp[2])
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)
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{
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| 309 |
int hd, w, i;
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int g0, g1;
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FVECT wp[2], mov;
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double d;
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/* do each wall on each section */
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for (hd = 0; hdlist[hd] != NULL; hd++)
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for (w = 0; w < 6; w++) {
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g0 = hdwg0[w];
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g1 = hdwg1[w];
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d = 1.0/hdlist[hd]->grid[g0];
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mov[0] = d * hdlist[hd]->xv[g0][0];
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mov[1] = d * hdlist[hd]->xv[g0][1];
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mov[2] = d * hdlist[hd]->xv[g0][2];
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if (w & 1) {
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| 323 |
VSUM(wp[0], hdlist[hd]->orig,
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hdlist[hd]->xv[w>>1], 1.);
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| 325 |
VSUM(wp[0], wp[0], mov, 1.);
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| 326 |
} else
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| 327 |
VCOPY(wp[0], hdlist[hd]->orig);
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| 328 |
VSUM(wp[1], wp[0], hdlist[hd]->xv[g1], 1.);
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| 329 |
for (i = hdlist[hd]->grid[g0]; ; ) { /* g0 lines */
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| 330 |
(*f)(wp);
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| 331 |
if (!--i) break;
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| 332 |
wp[0][0] += mov[0]; wp[0][1] += mov[1];
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| 333 |
wp[0][2] += mov[2]; wp[1][0] += mov[0];
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| 334 |
wp[1][1] += mov[1]; wp[1][2] += mov[2];
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| 335 |
}
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| 336 |
d = 1.0/hdlist[hd]->grid[g1];
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| 337 |
mov[0] = d * hdlist[hd]->xv[g1][0];
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| 338 |
mov[1] = d * hdlist[hd]->xv[g1][1];
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| 339 |
mov[2] = d * hdlist[hd]->xv[g1][2];
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| 340 |
if (w & 1)
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| 341 |
VSUM(wp[0], hdlist[hd]->orig,
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| 342 |
hdlist[hd]->xv[w>>1], 1.);
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| 343 |
else
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| 344 |
VSUM(wp[0], hdlist[hd]->orig, mov, 1.);
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| 345 |
VSUM(wp[1], wp[0], hdlist[hd]->xv[g0], 1.);
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| 346 |
for (i = hdlist[hd]->grid[g1]; ; ) { /* g1 lines */
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| 347 |
(*f)(wp);
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| 348 |
if (!--i) break;
|
| 349 |
wp[0][0] += mov[0]; wp[0][1] += mov[1];
|
| 350 |
wp[0][2] += mov[2]; wp[1][0] += mov[0];
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| 351 |
wp[1][1] += mov[1]; wp[1][2] += mov[2];
|
| 352 |
}
|
| 353 |
}
|
| 354 |
}
|
