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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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* Routines for tracking beam compuatations |
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*/ |
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|
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#include "rholo.h" |
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|
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|
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#define abs(x) ((x) > 0 ? (x) : -(x)) |
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#define sgn(x) ((x) > 0 ? 1 : (x) < 0 ? -1 : 0) |
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|
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|
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static PACKHEAD *complist; /* list of beams to compute */ |
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static int complen; /* length of complist */ |
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static int listpos; /* current list position for next_pack */ |
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static int lastin; /* last ordered position in list */ |
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|
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|
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int |
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weightf(hp, x0, x1, x2) /* voxel weighting function */ |
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register HOLO *hp; |
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register int x0, x1, x2; |
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{ |
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switch (vlet(OCCUPANCY)) { |
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case 'U': /* uniform weighting */ |
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return(1); |
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case 'C': /* center weighting (crude) */ |
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x0 += x0 - hp->grid[0] + 1; |
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x0 = abs(x0)*hp->grid[1]*hp->grid[2]; |
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x1 += x1 - hp->grid[1] + 1; |
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x1 = abs(x1)*hp->grid[0]*hp->grid[2]; |
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x2 += x2 - hp->grid[2] + 1; |
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x2 = abs(x2)*hp->grid[0]*hp->grid[1]; |
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return(hp->grid[0]*hp->grid[1]*hp->grid[2] - |
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(x0+x1+x2)/3); |
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default: |
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badvalue(OCCUPANCY); |
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} |
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} |
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|
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|
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/* The following is by Daniel Cohen, taken from Graphics Gems IV, p. 368 */ |
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long |
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lineweight(hp, x, y, z, dx, dy, dz) /* compute weights along a line */ |
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HOLO *hp; |
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int x, y, z, dx, dy, dz; |
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{ |
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long wres = 0; |
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int n, sx, sy, sz, exy, exz, ezy, ax, ay, az, bx, by, bz; |
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|
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sx = sgn(dx); sy = sgn(dy); sz = sgn(dz); |
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ax = abs(dx); ay = abs(dy); az = abs(dz); |
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bx = 2*ax; by = 2*ay; bz = 2*az; |
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exy = ay-ax; exz = az-ax; ezy = ay-az; |
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n = ax+ay+az + 1; /* added increment to visit last */ |
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while (n--) { |
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wres += weightf(hp, x, y, z); |
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if (exy < 0) { |
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if (exz < 0) { |
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x += sx; |
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exy += by; exz += bz; |
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} else { |
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z += sz; |
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exz -= bx; ezy += by; |
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} |
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} else { |
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if (ezy < 0) { |
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z += sz; |
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exz -= bx; ezy += by; |
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} else { |
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y += sy; |
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exy -= bx; ezy -= bz; |
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} |
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} |
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} |
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return(wres); |
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} |
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|
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|
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int |
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beamcmp(b0, b1) /* comparison for descending compute order */ |
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register PACKHEAD *b0, *b1; |
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{ |
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return( b1->nr*(bnrays(hdlist[b0->hd],b0->bi)+1) - |
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b0->nr*(bnrays(hdlist[b1->hd],b1->bi)+1) ); |
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} |
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|
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|
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init_global() /* initialize global ray computation */ |
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{ |
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long wtotal = 0; |
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int i, j; |
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int lseg[2][3]; |
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double frac; |
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register int k; |
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/* allocate beam list */ |
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complen = 0; |
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for (j = 0; hdlist[j] != NULL; j++) |
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complen += nbeams(hdlist[j]); |
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complist = (PACKHEAD *)malloc(complen*sizeof(PACKHEAD)); |
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if (complist == NULL) |
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error(SYSTEM, "out of memory in init_global"); |
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/* compute beam weights */ |
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k = 0; |
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for (j = 0; hdlist[j] != NULL; j++) |
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for (i = nbeams(hdlist[j]); i > 0; i--) { |
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hdlseg(lseg, hdlist[j], i); |
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complist[k].hd = j; |
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complist[k].bi = i; |
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complist[k].nr = lineweight( hdlist[j], |
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lseg[0][0], lseg[0][1], lseg[0][2], |
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lseg[1][0] - lseg[0][0], |
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lseg[1][1] - lseg[0][1], |
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lseg[1][2] - lseg[0][2] ); |
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wtotal += complist[k++].nr; |
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} |
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/* adjust weights */ |
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if (vdef(DISKSPACE)) { |
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frac = 1024.*1024.*vflt(DISKSPACE) / (wtotal*sizeof(RAYVAL)); |
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if (frac < 0.95 | frac > 1.05) |
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while (k--) |
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complist[k].nr = frac * complist[k].nr; |
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} |
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listpos = 0; lastin = -1; |
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} |
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|
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|
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mergeclists(cdest, cl1, n1, cl2, n2) /* merge two sorted lists */ |
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PACKHEAD *cdest; |
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PACKHEAD *cl1, *cl2; |
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int n1, n2; |
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{ |
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int cmp; |
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|
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while (n1 | n2) { |
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if (!n1) cmp = 1; |
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else if (!n2) cmp = -1; |
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else cmp = beamcmp(cl1, cl2); |
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if (cmp > 0) { |
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copystruct(cdest, cl2); |
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cl2++; n2--; |
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} else { |
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copystruct(cdest, cl1); |
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cl1++; n1--; |
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} |
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cdest++; |
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} |
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} |
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|
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|
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sortcomplist() /* fix our list order */ |
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{ |
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PACKHEAD *list2; |
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/* empty queue */ |
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done_packets(flush_queue()); |
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if (lastin < 0) /* flag to sort entire list */ |
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qsort((char *)complist, complen, sizeof(PACKHEAD), beamcmp); |
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else if (listpos) { /* else sort and merge sublist */ |
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list2 = (PACKHEAD *)malloc(listpos*sizeof(PACKHEAD)); |
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if (list2 == NULL) |
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error(SYSTEM, "out of memory in sortcomplist"); |
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bcopy((char *)complist,(char *)list2,listpos*sizeof(PACKHEAD)); |
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qsort((char *)list2, listpos, sizeof(PACKHEAD), beamcmp); |
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mergeclists(complist, list2, listpos, |
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complist+listpos, complen-listpos); |
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free((char *)list2); |
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} |
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listpos = 0; lastin = complen-1; |
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} |
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|
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|
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/* |
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* The following routine works on the assumption that the bundle weights are |
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* more or less evenly distributed, such that computing a packet causes |
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* a given bundle to move way down in the computation order. We keep |
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* track of where the computed bundle with the highest priority would end |
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* up, and if we get further in our compute list than this, we resort the |
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* list and start again from the beginning. We have to flush the queue |
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* each time we sort, to ensure that we are not disturbing the order. |
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* If our major assumption is violated, and we have a very steep |
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* descent in our weights, then we will end up resorting much more often |
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* than necessary, resulting in frequent flushing of the queue. Since |
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* a merge sort is used, the sorting costs will be minimal. |
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*/ |
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next_packet(p) /* prepare packet for computation */ |
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register PACKET *p; |
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{ |
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int ncomp; |
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register int i; |
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|
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if (complen <= 0) |
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return(0); |
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if (listpos > lastin) /* time to sort the list */ |
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sortcomplist(); |
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p->hd = complist[listpos].hd; |
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p->bi = complist[listpos].bi; |
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ncomp = bnrays(hdlist[p->hd],p->bi); |
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p->nr = complist[listpos].nr - ncomp; |
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if (p->nr <= 0) |
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return(0); |
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if (p->nr > RPACKSIZ) |
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p->nr = RPACKSIZ; |
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ncomp += p->nr; /* find where this one would go */ |
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while (lastin > listpos && complist[listpos].nr * |
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(bnrays(hdlist[complist[lastin].hd],complist[lastin].bi)+1) |
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> complist[lastin].nr * (ncomp+1)) |
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lastin--; |
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listpos++; |
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return(1); |
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} |
