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/* Copyright (c) 1998 Silicon Graphics, Inc. */ |
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|
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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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/* |
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* Routines for converting holodeck coordinates, etc. |
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* |
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* 10/22/97 GWLarson |
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*/ |
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|
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#include "holo.h" |
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|
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float hd_depthmap[DCINF-DCLIN]; |
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|
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int hdwg0[6] = {1,1,2,2,0,0}; |
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int hdwg1[6] = {2,2,0,0,1,1}; |
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|
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static double logstep; |
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|
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|
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hdcompgrid(hp) /* compute derived grid vector and index */ |
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register HOLO *hp; |
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{ |
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double d; |
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register int i, j; |
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/* initialize depth map */ |
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if (hd_depthmap[0] < 1.) { |
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d = 1. + .5/DCLIN; |
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for (i = 0; i < DCINF-DCLIN; i++) { |
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hd_depthmap[i] = d; |
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d *= 1. + 1./DCLIN; |
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} |
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logstep = log(1. + 1./DCLIN); |
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} |
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/* compute grid coordinate vectors */ |
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for (i = 0; i < 3; i++) { |
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fcross(hp->wg[i], hp->xv[(i+1)%3], hp->xv[(i+2)%3]); |
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d = DOT(hp->wg[i],hp->xv[i]); |
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if (d <= FTINY & d >= -FTINY) |
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error(USER, "degenerate holodeck section"); |
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d = hp->grid[i] / d; |
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hp->wg[i][0] *= d; hp->wg[i][1] *= d; hp->wg[i][2] *= d; |
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} |
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/* compute linear depth range */ |
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hp->tlin = VLEN(hp->xv[0]) + VLEN(hp->xv[1]) + VLEN(hp->xv[2]); |
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/* compute wall super-indices from grid */ |
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hp->wi[0] = 1; /**** index values begin at 1 ****/ |
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for (i = 1; i < 6; i++) { |
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hp->wi[i] = 0; |
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for (j = i; j < 6; j++) |
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hp->wi[i] += hp->grid[hdwg0[j]] * hp->grid[hdwg1[j]]; |
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hp->wi[i] *= hp->grid[hdwg0[i-1]] * hp->grid[hdwg1[i-1]]; |
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hp->wi[i] += hp->wi[i-1]; |
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} |
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} |
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|
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|
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hdbcoord(gc, hp, i) /* compute beam coordinates from index */ |
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GCOORD gc[2]; /* returned */ |
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register HOLO *hp; |
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register int i; |
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{ |
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register int j, n; |
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int n2, reverse; |
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GCOORD g2[2]; |
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/* check range */ |
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if (i < 1 | i > nbeams(hp)) |
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return(0); |
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if (reverse = i >= hp->wi[5]) |
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i -= hp->wi[5] - 1; |
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for (j = 0; j < 5; j++) /* find w0 */ |
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if (hp->wi[j+1] > i) |
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break; |
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i -= hp->wi[gc[0].w=j]; |
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/* find w1 */ |
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n2 = hp->grid[hdwg0[j]] * hp->grid[hdwg1[j]]; |
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while (++j < 5) { |
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n = n2 * hp->grid[hdwg0[j]] * hp->grid[hdwg1[j]]; |
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if (n > i) |
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break; |
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i -= n; |
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} |
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gc[1].w = j; |
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/* find position on w0 */ |
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n2 = hp->grid[hdwg0[j]] * hp->grid[hdwg1[j]]; |
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n = i / n2; |
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gc[0].i[1] = n / hp->grid[hdwg0[gc[0].w]]; |
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gc[0].i[0] = n - gc[0].i[1]*hp->grid[hdwg0[gc[0].w]]; |
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i -= n*n2; |
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/* find position on w1 */ |
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gc[1].i[1] = i / hp->grid[hdwg0[gc[1].w]]; |
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gc[1].i[0] = i - gc[1].i[1]*hp->grid[hdwg0[gc[1].w]]; |
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if (reverse) { |
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copystruct(g2, gc+1); |
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copystruct(gc+1, gc); |
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copystruct(gc, g2); |
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} |
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return(1); /* we're done */ |
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} |
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|
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|
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int |
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hdbindex(hp, gc) /* compute index from beam coordinates */ |
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register HOLO *hp; |
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register GCOORD gc[2]; |
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{ |
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GCOORD g2[2]; |
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int reverse; |
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register int i, j; |
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/* check ordering and limits */ |
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if (reverse = gc[0].w > gc[1].w) { |
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copystruct(g2, gc+1); |
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copystruct(g2+1, gc); |
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gc = g2; |
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} else if (gc[0].w == gc[1].w) |
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return(0); |
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if (gc[0].w < 0 | gc[1].w > 5) |
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return(0); |
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i = 0; /* compute index */ |
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for (j = gc[0].w+1; j < gc[1].w; j++) |
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i += hp->grid[hdwg0[j]] * hp->grid[hdwg1[j]]; |
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i *= hp->grid[hdwg0[gc[0].w]] * hp->grid[hdwg1[gc[0].w]]; |
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i += hp->wi[gc[0].w]; |
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i += (hp->grid[hdwg0[gc[0].w]]*gc[0].i[1] + gc[0].i[0]) * |
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hp->grid[hdwg0[gc[1].w]] * hp->grid[hdwg1[gc[1].w]] ; |
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i += hp->grid[hdwg0[gc[1].w]]*gc[1].i[1] + gc[1].i[0]; |
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if (reverse) |
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i += hp->wi[5] - 1; |
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return(i); |
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} |
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|
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|
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hdcell(cp, hp, gc) /* compute cell coordinates */ |
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register FVECT cp[4]; /* returned (may be passed as FVECT cp[2][2]) */ |
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register HOLO *hp; |
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register GCOORD *gc; |
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{ |
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register FLOAT *v; |
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double d; |
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/* compute common component */ |
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VCOPY(cp[0], hp->orig); |
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if (gc->w & 1) { |
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v = hp->xv[gc->w>>1]; |
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cp[0][0] += v[0]; cp[0][1] += v[1]; cp[0][2] += v[2]; |
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} |
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v = hp->xv[hdwg0[gc->w]]; |
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d = (double)gc->i[0] / hp->grid[hdwg0[gc->w]]; |
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VSUM(cp[0], cp[0], v, d); |
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v = hp->xv[hdwg1[gc->w]]; |
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d = (double)gc->i[1] / hp->grid[hdwg1[gc->w]]; |
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VSUM(cp[0], cp[0], v, d); |
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/* compute x1 sums */ |
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v = hp->xv[hdwg0[gc->w]]; |
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d = 1.0 / hp->grid[hdwg0[gc->w]]; |
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VSUM(cp[1], cp[0], v, d); |
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VSUM(cp[3], cp[0], v, d); |
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/* compute y1 sums */ |
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v = hp->xv[hdwg1[gc->w]]; |
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d = 1.0 / hp->grid[hdwg1[gc->w]]; |
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VSUM(cp[2], cp[0], v, d); |
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VSUM(cp[3], cp[3], v, d); |
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} |
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|
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|
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hdlseg(lseg, hp, gc) /* compute line segment for beam */ |
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register int lseg[2][3]; |
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register HOLO *hp; |
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GCOORD gc[2]; |
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{ |
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register int k; |
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|
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for (k = 0; k < 2; k++) { /* compute end points */ |
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lseg[k][gc[k].w>>1] = gc[k].w&1 ? hp->grid[gc[k].w>>1]-1 : 0 ; |
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lseg[k][hdwg0[gc[k].w]] = gc[k].i[0]; |
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lseg[k][hdwg1[gc[k].w]] = gc[k].i[1]; |
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} |
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return(1); |
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} |
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|
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|
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unsigned |
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hdcode(hp, d) /* compute depth code for d */ |
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HOLO *hp; |
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double d; |
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{ |
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double tl = hp->tlin; |
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register long c; |
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|
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if (d <= 0.) |
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return(0); |
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if (d >= .99*FHUGE) |
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return(DCINF); |
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if (d < tl) |
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return((unsigned)(d*DCLIN/tl)); |
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c = (long)(log(d/tl)/logstep) + DCLIN; |
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return(c > DCINF ? (unsigned)DCINF : (unsigned)c); |
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} |
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|
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|
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hdgrid(gp, hp, wp) /* compute grid coordinates */ |
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FVECT gp; /* returned */ |
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register HOLO *hp; |
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FVECT wp; |
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{ |
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FVECT vt; |
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|
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VSUB(vt, wp, hp->orig); |
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gp[0] = DOT(vt, hp->wg[0]); |
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gp[1] = DOT(vt, hp->wg[1]); |
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gp[2] = DOT(vt, hp->wg[2]); |
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} |
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|
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|
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hdworld(wp, hp, gp) /* compute world coordinates */ |
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register FVECT wp; |
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register HOLO *hp; |
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FVECT gp; |
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{ |
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register double d; |
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|
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d = gp[0]/hp->grid[0]; |
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VSUM(wp, hp->orig, hp->xv[0], d); |
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|
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d = gp[1]/hp->grid[1]; |
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VSUM(wp, wp, hp->xv[1], d); |
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|
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d = gp[2]/hp->grid[2]; |
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VSUM(wp, wp, hp->xv[2], d); |
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} |
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|
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|
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double |
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hdray(ro, rd, hp, gc, r) /* compute ray within a beam */ |
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FVECT ro, rd; /* returned */ |
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HOLO *hp; |
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GCOORD gc[2]; |
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BYTE r[2][2]; |
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{ |
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FVECT cp[4], p[2]; |
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register int i, j; |
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double d0, d1; |
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/* compute entry and exit points */ |
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for (i = 0; i < 2; i++) { |
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hdcell(cp, hp, gc+i); |
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d0 = (1./256.)*(r[i][0]+.5); |
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d1 = (1./256.)*(r[i][1]+.5); |
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for (j = 0; j < 3; j++) |
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p[i][j] = (1.-d0-d1)*cp[0][j] + |
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d0*cp[1][j] + d1*cp[2][j]; |
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} |
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VCOPY(ro, p[0]); /* assign ray origin and direction */ |
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VSUB(rd, p[1], p[0]); |
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return(normalize(rd)); /* return maximum inside distance */ |
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} |
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|
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|
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double |
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hdinter(gc, r, ed, hp, ro, rd) /* compute ray intersection with section */ |
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register GCOORD gc[2]; /* returned */ |
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BYTE r[2][2]; /* returned (optional) */ |
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double *ed; /* returned (optional) */ |
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register HOLO *hp; |
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FVECT ro, rd; /* normalization of rd affects distances */ |
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{ |
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FVECT p[2], vt; |
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double d, t0, t1, d0, d1; |
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register FLOAT *v; |
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register int i; |
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/* first, intersect walls */ |
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gc[0].w = gc[1].w = -1; |
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t0 = -FHUGE; t1 = FHUGE; |
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VSUB(vt, ro, hp->orig); |
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for (i = 0; i < 3; i++) { /* for each wall pair */ |
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d = -DOT(rd, hp->wg[i]); /* plane distance */ |
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if (d <= FTINY && d >= -FTINY) /* check for parallel */ |
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continue; |
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d1 = DOT(vt, hp->wg[i]); /* ray distances */ |
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d0 = d1 / d; |
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d1 = (d1 - hp->grid[i]) / d; |
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if (d < 0) { /* check against best */ |
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if (d0 > t0) { |
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t0 = d0; |
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gc[0].w = i<<1; |
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} |
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if (d1 < t1) { |
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t1 = d1; |
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gc[1].w = i<<1 | 1; |
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} |
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} else { |
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if (d1 > t0) { |
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t0 = d1; |
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gc[0].w = i<<1 | 1; |
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} |
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if (d0 < t1) { |
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t1 = d0; |
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gc[1].w = i<<1; |
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} |
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} |
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} |
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if (gc[0].w < 0 | gc[1].w < 0) /* paranoid check */ |
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return(FHUGE); |
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/* compute intersections */ |
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VSUM(p[0], ro, rd, t0); |
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VSUM(p[1], ro, rd, t1); |
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/* now, compute grid coordinates */ |
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for (i = 0; i < 2; i++) { |
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VSUB(vt, p[i], hp->orig); |
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v = hp->wg[hdwg0[gc[i].w]]; |
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d = DOT(vt, v); |
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if (d < 0 || d >= hp->grid[hdwg0[gc[i].w]]) |
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return(FHUGE); /* outside wall */ |
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gc[i].i[0] = d; |
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if (r != NULL) |
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r[i][0] = 256. * (d - gc[i].i[0]); |
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v = hp->wg[hdwg1[gc[i].w]]; |
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d = DOT(vt, v); |
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if (d < 0 || d >= hp->grid[hdwg1[gc[i].w]]) |
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return(FHUGE); /* outside wall */ |
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gc[i].i[1] = d; |
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if (r != NULL) |
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r[i][1] = 256. * (d - gc[i].i[1]); |
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} |
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if (ed != NULL) /* assign distance to exit point */ |
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*ed = t1; |
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return(t0); /* return distance to entry point */ |
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} |
