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gregl |
3.1 |
/* 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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* Holodeck beam support |
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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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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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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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hdcell(cp, hp, gc+1); |
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for (i = 0; i < 4; i++) { |
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viewloc(ip[i], vp, 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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* 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[1]; |
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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 && d >= -FTINY) { |
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if (t < 0) |
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goto nextscan; |
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continue; |
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} |
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if (t > 0) { |
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if ((t /= d) < lend) |
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lend = t; |
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} else { |
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if ((t /= d) > lbeg) |
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lbeg = t; |
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} |
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} |
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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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nextscan:; |
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} |
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} |
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return(n); |
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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 int *cl; |
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{ |
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copystruct((GCOORD *)(cl+1) + *cl, gcp); |
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(*cl)++; |
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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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register GCOORD *gcp1, *gcp2; |
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{ |
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register 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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int * |
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getviewcells(hp, vp) /* get ordered cell list for section view */ |
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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 n; |
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register int *cl; |
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/* compute view pyramid */ |
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if (vp->type == VT_PAR) goto viewerr; |
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if (viewray(org, dir[0], vp, 0., 0.) < -FTINY) goto viewerr; |
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if (viewray(org, dir[1], vp, 0., 1.) < -FTINY) goto viewerr; |
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if (viewray(org, dir[2], vp, 1., 1.) < -FTINY) goto viewerr; |
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if (viewray(org, dir[3], vp, 1., 0.) < -FTINY) goto viewerr; |
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/* allocate enough list space */ |
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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 = (int *)malloc(sizeof(int) + n*sizeof(GCOORD)); |
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if (cl == NULL) |
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goto memerr; |
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*cl = 0; |
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/* add cells within pyramid */ |
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visit_cells(org, dir, hp, addcell, cl); |
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if (!*cl) { |
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free((char *)cl); |
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return(NULL); |
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} |
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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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if (*cl < n) { /* optimize memory use */ |
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cl = (int *)realloc((char *)cl, |
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sizeof(int) + *cl*sizeof(GCOORD)); |
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if (cl == NULL) |
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goto memerr; |
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} |
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/* sort the list */ |
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qsort((char *)(cl+1), *cl, sizeof(GCOORD), cellcmp); |
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#endif |
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return(cl); |
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viewerr: |
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error(INTERNAL, "unusable view in getviewcells"); |
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memerr: |
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error(SYSTEM, "out of memory in getviewcells"); |
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} |
