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/* Copyright (c) 1997 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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* Holodeck beam support for display process |
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*/ |
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|
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#include "rholo.h" |
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#include "rhdisp.h" |
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#include "view.h" |
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|
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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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|
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|
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int |
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npixels(vp, hr, vr, hp, bi) /* compute appropriate number 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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static VIEW vdo, vlast; |
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static HOLO *hplast; |
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GCOORD gc[2]; |
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FVECT cp[4]; |
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FVECT ip[4]; |
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double d; |
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register int i; |
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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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/* has holodeck or view changed? */ |
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if (hp != hplast || bcmp((char *)vp, (char *)&vlast, sizeof(VIEW))) { |
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copystruct(&vdo, vp); |
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if (sect_behind(hp, &vdo)) { /* reverse view sense */ |
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vdo.vdir[0] = -vdo.vdir[0]; |
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vdo.vdir[1] = -vdo.vdir[1]; |
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vdo.vdir[2] = -vdo.vdir[2]; |
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setview(&vdo); |
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} |
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hplast = hp; |
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copystruct(&vlast, vp); |
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} |
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hdcell(cp, hp, gc+1); /* find cell on image */ |
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for (i = 0; i < 4; i++) { |
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viewloc(ip[i], &vdo, cp[i]); |
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if (ip[i][2] < 0.) |
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return(0); |
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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 quad area */ |
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d = (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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d += (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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if (d < 0) |
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d = -d; |
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/* round off result */ |
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return((int)(.5*d+.5)); |
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} |
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|
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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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*/ |
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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 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; |
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register 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[((gc.w>>1)+2)%3]; 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[((gc.w>>1)+1)%3] = 0; |
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gp[((gc.w>>1)+2)%3] = gc.i[1] + 0.5; |
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hdworld(lo, hp, gp); |
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gp[((gc.w>>1)+1)%3] = 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[((gc.w>>1)+1)%3]; |
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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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} |
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} |
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return(n); |
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} |
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|
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|
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sect_behind(hp, vp) /* check if section is "behind" viewpoint */ |
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register HOLO *hp; |
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register 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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|
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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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register 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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|
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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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register struct cellist *cl; |
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{ |
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copystruct(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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|
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|
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int |
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cellcmp(gcp1, gcp2) /* visit_cells() cell ordering */ |
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register GCOORD *gcp1, *gcp2; |
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{ |
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register int c; |
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|
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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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|
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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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register 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, &cl); |
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if (!cl.n) { |
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free((char *)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((char *)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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} |
