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/* Copyright (c) 1997 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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* 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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#include "holo.h"
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float hd_depthmap[DCINF-DCLIN];
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static double logstep;
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static int wg0[6] = {1,1,2,2,0,0};
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static int wg1[6] = {2,2,0,0,1,1};
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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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FVECT AxB;
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double d;
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register FLOAT *v;
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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(AxB, hp->xv[(i+1)%3], v=hp->xv[(i+2)%3]);
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VCOPY(hp->wn[i], AxB);
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if (normalize(hp->wn[i]) == 0.)
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error(USER, "degenerate holodeck section");
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hp->wo[i<<1] = DOT(hp->wn[i],hp->orig);
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hp->wo[i<<1|1] = hp->wo[i<<1] + DOT(hp->wn[i],hp->xv[i]);
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fcross(hp->gv[i][0], v, AxB);
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d = DOT(v,v) / DOT(hp->gv[i][0],hp->gv[i][0]) *
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hp->grid[(i+1)%3];
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for (j = 0; j < 3; j++)
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hp->gv[i][0][j] *= d;
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fcross(hp->gv[i][1], AxB, v=hp->xv[(i+1)%3]);
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d = DOT(v,v) / DOT(hp->gv[i][1],hp->gv[i][1]) *
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hp->grid[(i+2)%3];
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for (j = 0; j < 3; j++)
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hp->gv[i][1][j] *= 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[wg0[j]] * hp->grid[wg1[j]];
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hp->wi[i] *= hp->grid[wg0[i-1]] * hp->grid[wg1[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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HOLO *
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hdalloc(hproto) /* allocate and set holodeck section based on grid */
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HDGRID *hproto;
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{
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HOLO hdhead;
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register HOLO *hp;
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int n;
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/* copy grid to temporary header */
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bcopy((char *)hproto, (char *)&hdhead, sizeof(HDGRID));
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/* compute grid vectors and sizes */
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hdcompgrid(&hdhead);
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/* allocate header with directory */
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n = sizeof(HOLO)+nbeams(&hdhead)*sizeof(BEAMI);
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if ((hp = (HOLO *)malloc(n)) == NULL)
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return(NULL);
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/* copy header information */
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copystruct(hp, &hdhead);
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/* allocate and clear beam list */
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hp->bl = (BEAM **)malloc((nbeams(hp)+1)*sizeof(BEAM *)+sizeof(BEAM));
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if (hp->bl == NULL) {
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free((char *)hp);
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return(NULL);
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}
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bzero((char *)hp->bl, (nbeams(hp)+1)*sizeof(BEAM *)+sizeof(BEAM));
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hp->bl[0] = (BEAM *)(hp->bl+nbeams(hp)+1); /* set blglob(hp) */
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hp->fd = -1;
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hp->dirty = 0;
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hp->priv = NULL;
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/* clear beam directory */
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bzero((char *)hp->bi, (nbeams(hp)+1)*sizeof(BEAMI));
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return(hp); /* all is well */
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}
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hdbcoord(gc, hp, i) /* compute beam coordinates from index */
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BCOORD gc; /* 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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BCOORD g2;
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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[wg0[j]] * hp->grid[wg1[j]];
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while (++j < 5) {
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n = n2 * hp->grid[wg0[j]] * hp->grid[wg1[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[wg0[j]] * hp->grid[wg1[j]];
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n = i / n2;
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gc[0].i[1] = n / hp->grid[wg0[gc[0].w]];
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gc[0].i[0] = n - gc[0].i[1]*hp->grid[wg0[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[wg0[gc[1].w]];
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gc[1].i[0] = i - gc[1].i[1]*hp->grid[wg0[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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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 BCOORD gc;
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{
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BCOORD g2;
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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[wg0[j]] * hp->grid[wg1[j]];
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i *= hp->grid[wg0[gc[0].w]] * hp->grid[wg1[gc[0].w]];
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i += hp->wi[gc[0].w];
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i += (hp->grid[wg0[gc[0].w]]*gc[0].i[1] + gc[0].i[0]) *
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hp->grid[wg0[gc[1].w]] * hp->grid[wg1[gc[1].w]] ;
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i += hp->grid[wg0[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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hdlseg(lseg, hp, i) /* 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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int i;
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{
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BCOORD gc;
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register int k;
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if (!hdbcoord(gc, hp, i)) /* compute grid coordinates */
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return(0);
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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][wg0[gc[k].w]] = gc[k].i[0];
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lseg[k][wg1[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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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 unsigned c;
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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 = (unsigned)(log(d/tl)/logstep) + DCLIN;
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return(c > DCINF ? DCINF : c);
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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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register HOLO *hp;
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register BCOORD gc;
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BYTE r[2][2];
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{
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FVECT p[2];
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register int i;
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register FLOAT *v;
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double d;
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/* compute entry and exit points */
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for (i = 0; i < 2; i++) {
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VCOPY(p[i], hp->orig);
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if (gc[i].w & 1) {
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v = hp->xv[gc[i].w>>1];
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p[i][0] += *v++; p[i][1] += *v++; p[i][2] += *v;
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}
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d = ( gc[i].i[0] + (1./256.)*(r[i][0]+.5) ) /
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hp->grid[wg0[gc[i].w]];
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v = hp->xv[wg0[gc[i].w]];
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p[i][0] += d * *v++; p[i][1] += d * *v++; p[i][2] += d * *v;
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d = (gc[i].i[1] + (1./256.)*(r[i][1]+.5)) /
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hp->grid[wg1[gc[i].w]];
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v = hp->xv[wg1[gc[i].w]];
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p[i][0] += d * *v++; p[i][1] += d * *v++; p[i][2] += d * *v;
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}
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VCOPY(ro, p[0]); /* assign ray origin and direction */
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rd[0] = p[1][0] - p[0][0];
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rd[1] = p[1][1] - p[0][1];
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rd[2] = p[1][2] - p[0][2];
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return(normalize(rd)); /* return maximum inside distance */
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}
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double
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hdinter(gc, r, hp, ro, rd) /* compute ray intersection with section */
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register BCOORD gc; /* returned */
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BYTE r[2][2]; /* returned */
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register HOLO *hp;
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FVECT ro, rd; /* rd should be normalized */
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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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for (i = 0; i < 3; i++) { /* for each wall pair */
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d = -DOT(rd, hp->wn[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(ro, hp->wn[i]); /* ray distances */
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d0 = (d1 - hp->wo[i<<1]) / d;
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d1 = (d1 - hp->wo[i<<1|1]) / d;
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if (d0 < d1) { /* 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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for (i = 0; i < 3; i++) {
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p[0][i] = ro[i] + rd[i]*t0;
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p[1][i] = ro[i] + rd[i]*t1;
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}
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/* now, compute grid coordinates */
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for (i = 0; i < 2; i++) {
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vt[0] = p[i][0] - hp->orig[0];
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vt[1] = p[i][1] - hp->orig[1];
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vt[2] = p[i][2] - hp->orig[2];
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if (gc[i].w & 1) {
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v = hp->xv[gc[i].w>>1];
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vt[0] -= *v++; vt[1] -= *v++; vt[2] -= *v;
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}
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v = hp->gv[gc[i].w>>1][0];
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d = DOT(vt, v);
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if (d < 0. || (gc[i].i[0] = d) >= hp->grid[wg0[gc[i].w]])
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return(FHUGE); /* outside wall */
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r[i][0] = 256. * (d - gc[i].i[0]);
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v = hp->gv[gc[i].w>>1][1];
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d = DOT(vt, v);
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if (d < 0. || (gc[i].i[1] = d) >= hp->grid[wg1[gc[i].w]])
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return(FHUGE); /* outside wall */
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r[i][1] = 256. * (d - gc[i].i[1]);
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}
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/* return distance from entry point */
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vt[0] = ro[0] - p[0][0];
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vt[1] = ro[1] - p[0][1];
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vt[2] = ro[2] - p[0][2];
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return(DOT(vt,rd));
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}
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