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/* Copyright (c) 1996 Regents of the University of California */ |
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|
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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|
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/* |
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* Draw small sources into image in case we missed them. |
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*/ |
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|
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#include "ray.h" |
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|
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#include "view.h" |
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|
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#include "source.h" |
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|
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|
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#define CLIP_ABOVE 1 |
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#define CLIP_BELOW 2 |
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#define CLIP_RIGHT 3 |
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#define CLIP_LEFT 4 |
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|
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#define MAXVERT 10 |
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|
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|
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static int |
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inregion(p, cv, crit) /* check if vertex is in region */ |
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FLOAT p[2]; |
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double cv; |
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int crit; |
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{ |
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switch (crit) { |
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case CLIP_ABOVE: |
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return(p[1] < cv); |
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case CLIP_BELOW: |
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return(p[1] >= cv); |
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case CLIP_RIGHT: |
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return(p[0] < cv); |
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case CLIP_LEFT: |
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return(p[0] >= cv); |
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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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static |
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clipregion(a, b, cv, crit, r) /* find intersection with boundary */ |
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register FLOAT a[2], b[2]; |
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double cv; |
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int crit; |
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FLOAT r[2]; /* return value */ |
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{ |
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switch (crit) { |
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case CLIP_ABOVE: |
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case CLIP_BELOW: |
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r[1] = cv; |
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r[0] = a[0] + (cv-a[1])/(b[1]-a[1])*(b[0]-a[0]); |
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return; |
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case CLIP_RIGHT: |
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case CLIP_LEFT: |
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r[0] = cv; |
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r[1] = a[1] + (cv-a[0])/(b[0]-a[0])*(b[1]-a[1]); |
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return; |
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} |
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} |
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|
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|
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static int |
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hp_clip_poly(vl, nv, cv, crit, vlo) /* clip polygon to half-plane */ |
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FLOAT vl[][2]; |
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int nv; |
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double cv; |
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int crit; |
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FLOAT vlo[][2]; /* return value */ |
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{ |
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FLOAT *s, *p; |
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register int j, nvo; |
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|
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s = vl[nv-1]; |
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nvo = 0; |
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for (j = 0; j < nv; j++) { |
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p = vl[j]; |
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if (inregion(p, cv, crit)) { |
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if (!inregion(s, cv, crit)) |
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clipregion(s, p, cv, crit, vlo[nvo++]); |
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vlo[nvo][0] = p[0]; vlo[nvo++][1] = p[1]; |
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} else if (inregion(s, cv, crit)) |
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clipregion(s, p, cv, crit, vlo[nvo++]); |
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s = p; |
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} |
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return(nvo); |
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} |
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|
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|
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static int |
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box_clip_poly(vl, nv, xl, xr, yb, ya, vlo) /* clip polygon to box */ |
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FLOAT vl[MAXVERT][2]; |
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int nv; |
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double xl, xr, yb, ya; |
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FLOAT vlo[MAXVERT][2]; /* return value */ |
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{ |
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FLOAT vlt[MAXVERT][2]; |
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int nvt, nvo; |
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|
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nvt = hp_clip_poly(vl, nv, yb, CLIP_BELOW, vlt); |
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nvo = hp_clip_poly(vlt, nvt, ya, CLIP_ABOVE, vlo); |
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nvt = hp_clip_poly(vlo, nvo, xl, CLIP_LEFT, vlt); |
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nvo = hp_clip_poly(vlt, nvt, xr, CLIP_RIGHT, vlo); |
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|
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return(nvo); |
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} |
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|
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|
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static double |
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minw2(vl, nv, ar2) /* compute square of minimum width */ |
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FLOAT vl[][2]; |
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int nv; |
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double ar2; |
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{ |
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double d2, w2, w2min, w2max; |
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register FLOAT *p0, *p1, *p2; |
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int i, j; |
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/* find minimum for all widths */ |
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w2min = FHUGE; |
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p0 = vl[nv-1]; |
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for (i = 0; i < nv; i++) { /* for each edge */ |
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p1 = vl[i]; |
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d2 = (p1[0]-p0[0])*(p1[0]-p0[0]) + |
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(p1[1]-p0[1])*(p1[1]-p0[1])*ar2; |
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w2max = 0.; /* find maximum for this side */ |
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for (j = 1; j < nv-1; j++) { |
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p2 = vl[(i+j)%nv]; |
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w2 = (p1[0]-p0[0])*(p2[1]-p0[1]) - |
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(p1[1]-p0[1])*(p2[0]-p0[0]); |
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w2 = w2*w2*ar2/d2; /* triangle height squared */ |
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if (w2 > w2max) |
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w2max = w2; |
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} |
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if (w2max < w2min) /* global min. based on local max.'s */ |
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w2min = w2max; |
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p0 = p1; |
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} |
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return(w2min); |
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} |
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|
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|
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static |
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convex_center(vl, nv, cv) /* compute center of convex polygon */ |
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register FLOAT vl[][2]; |
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int nv; |
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FLOAT cv[2]; /* return value */ |
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{ |
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register int i; |
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/* simple average (suboptimal) */ |
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cv[0] = cv[1] = 0.; |
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for (i = 0; i < nv; i++) { |
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cv[0] += vl[i][0]; |
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cv[1] += vl[i][1]; |
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} |
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cv[0] /= (double)nv; |
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cv[1] /= (double)nv; |
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} |
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|
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|
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static double |
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poly_area(vl, nv) /* compute area of polygon */ |
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register FLOAT vl[][2]; |
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int nv; |
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{ |
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double a; |
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FLOAT v0[2], v1[2]; |
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register int i; |
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|
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a = 0.; |
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v0[0] = vl[1][0] - vl[0][0]; |
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v0[1] = vl[1][1] - vl[0][1]; |
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for (i = 2; i < nv; i++) { |
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v1[0] = vl[i][0] - vl[0][0]; |
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v1[1] = vl[i][1] - vl[0][1]; |
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a += v0[0]*v1[1] - v0[1]*v1[0]; |
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v0[0] = v1[0]; v0[1] = v1[1]; |
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} |
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return(a * (a >= 0. ? .5 : -.5)); |
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} |
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|
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|
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static int |
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convex_hull(vl, nv, vlo) /* compute polygon's convex hull */ |
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FLOAT vl[][2]; |
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int nv; |
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FLOAT vlo[][2]; /* return value */ |
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{ |
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int nvo, nvt; |
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FLOAT vlt[MAXVERT][2]; |
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double voa, vta; |
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register int i, j; |
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/* start with original polygon */ |
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for (i = nvo = nv; i--; ) { |
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vlo[i][0] = vl[i][0]; vlo[i][1] = vl[i][1]; |
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} |
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voa = poly_area(vlo, nvo); /* compute its area */ |
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for (i = 0; i < nvo; i++) { /* for each output vertex */ |
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for (j = 0; j < i; j++) { |
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vlt[j][0] = vlo[j][0]; vlt[j][1] = vlo[j][1]; |
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} |
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nvt = nvo - 1; /* make poly w/o vertex */ |
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for (j = i; j < nvt; j++) { |
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vlt[j][0] = vlo[j+1][0]; vlt[j][1] = vlo[j+1][1]; |
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} |
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vta = poly_area(vlt, nvt); |
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if (vta >= voa) { /* is simpler poly bigger? */ |
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voa = vta; /* then use it */ |
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for (j = nvo = nvt; j--; ) { |
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vlo[j][0] = vlt[j][0]; vlo[j][1] = vlt[j][1]; |
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} |
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i--; /* next adjust */ |
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} |
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} |
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return(nvo); |
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} |
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|
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|
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int |
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sourcepoly(vw, sn, sp) /* compute image polygon for source */ |
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VIEW *vw; |
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int sn; |
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FLOAT sp[MAXVERT][2]; |
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{ |
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static char cubeord[8][6] = {{1,3,2,6,4,5},{0,4,5,7,3,2}, |
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{0,1,3,7,6,4},{0,1,5,7,6,2}, |
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{0,2,6,7,5,1},{0,4,6,7,3,1}, |
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{0,2,3,7,5,4},{1,5,4,6,2,3}}; |
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register SRCREC *s = source + sn; |
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FVECT ap, ip; |
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FLOAT pt[6][2]; |
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int dir; |
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register int i, j; |
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|
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if (s->sflags & (SDISTANT|SFLAT)) { |
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if (s->sflags & SDISTANT && vw->type == VT_PAR) |
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return(0); /* all or nothing case */ |
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if (s->sflags & SFLAT) { |
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for (i = 0; i < 3; i++) |
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ap[i] = s->sloc[i] - vw->vp[i]; |
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if (DOT(ap, s->snorm) >= 0.) |
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return(0); /* source faces away */ |
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} |
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for (j = 0; j < 4; j++) { /* four corners */ |
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for (i = 0; i < 3; i++) { |
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ap[i] = s->sloc[i]; |
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if (j==1|j==2) ap[i] += s->ss[SU][i]; |
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else ap[i] -= s->ss[SU][i]; |
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if (j==2|j==3) ap[i] += s->ss[SV][i]; |
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else ap[i] -= s->ss[SV][i]; |
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if (s->sflags & SDISTANT) { |
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ap[i] *= 1. + vw->vfore; |
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ap[i] += vw->vp[i]; |
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} |
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} |
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viewloc(ip, vw, ap); /* find image point */ |
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if (ip[2] <= 0.) |
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return(0); /* in front of view */ |
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sp[j][0] = ip[0]; sp[j][1] = ip[1]; |
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} |
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return(4); |
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} |
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/* identify furthest corner */ |
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for (i = 0; i < 3; i++) |
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ap[i] = s->sloc[i] - vw->vp[i]; |
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dir = (DOT(ap,s->ss[SU])>0.) | |
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(DOT(ap,s->ss[SV])>0.)<<1 | |
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(DOT(ap,s->ss[SW])>0.)<<2 ; |
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/* order vertices based on this */ |
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for (j = 0; j < 6; j++) { |
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for (i = 0; i < 3; i++) { |
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ap[i] = s->sloc[i]; |
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if (cubeord[dir][j] & 1) ap[i] += s->ss[SU][i]; |
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else ap[i] -= s->ss[SU][i]; |
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if (cubeord[dir][j] & 2) ap[i] += s->ss[SV][i]; |
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else ap[i] -= s->ss[SV][i]; |
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if (cubeord[dir][j] & 4) ap[i] += s->ss[SW][i]; |
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else ap[i] -= s->ss[SW][i]; |
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} |
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viewloc(ip, vw, ap); /* find image point */ |
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if (ip[2] <= 0.) |
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return(0); /* in front of view */ |
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pt[j][0] = ip[0]; pt[j][1] = ip[1]; |
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} |
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return(convex_hull(pt, 6, sp)); /* make sure it's convex */ |
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} |
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|
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|
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/* add sources smaller than rad to computed subimage */ |
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drawsources(vw, xr, yr, pic, zbf, x0, xsiz, y0, ysiz, rad) |
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VIEW *vw; /* full image view */ |
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int xr, yr; /* full image dimensions */ |
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COLOR *pic[]; /* subimage pixel value array */ |
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float *zbf[]; /* subimage distance array (opt.) */ |
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int x0, xsiz, y0, ysiz; /* origin and size of subimage */ |
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int rad; /* source sample size */ |
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{ |
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int sn; |
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FLOAT spoly[MAXVERT][2], ppoly[MAXVERT][2]; |
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int nsv, npv; |
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int xmin, xmax, ymin, ymax, x, y, i; |
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FLOAT cxy[2]; |
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double pa; |
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RAY sr; |
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/* loop through all sources */ |
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for (sn = 0; sn < nsources; sn++) { |
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/* compute image polygon for source */ |
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if (!(nsv = sourcepoly(vw, sn, spoly))) |
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continue; |
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/* big enough for standard sampling? */ |
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if (minw2(spoly, nsv, vw->vn2/vw->hn2) > (double)rad*rad/xr/xr) |
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continue; |
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/* clip source poly to subimage */ |
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nsv = box_clip_poly(spoly, nsv, |
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(double)x0/xr, (double)(x0+xsiz)/xr, |
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(double)y0/yr, (double)(y0+ysiz)/yr, spoly); |
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if (!nsv) |
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continue; |
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/* find common subimage (BBox) */ |
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xmin = x0 + xsiz; xmax = x0; |
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ymin = y0 + ysiz; ymax = y0; |
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for (i = 0; i < nsv; i++) { |
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if ((double)xmin/xr > spoly[i][0]) |
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xmin = spoly[i][0]*xr + FTINY; |
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if ((double)xmax/xr < spoly[i][0]) |
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xmax = spoly[i][0]*xr - FTINY; |
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if ((double)ymin/yr > spoly[i][1]) |
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ymin = spoly[i][1]*yr + FTINY; |
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if ((double)ymax/yr < spoly[i][1]) |
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ymax = spoly[i][1]*yr - FTINY; |
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} |
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/* evaluate each pixel in BBox */ |
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for (y = ymin; y <= ymax; y++) |
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for (x = xmin; x <= xmax; x++) { |
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/* subarea for pixel */ |
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npv = box_clip_poly(spoly, nsv, |
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(double)x/xr, (x+1.)/xr, |
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(double)y/yr, (y+1.)/yr, ppoly); |
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if (!npv) |
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continue; /* no overlap */ |
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convex_center(ppoly, npv, cxy); |
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if ((sr.rmax = viewray(sr.rorg, sr.rdir, vw, |
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cxy[0], cxy[1])) < -FTINY) |
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continue; /* not in view */ |
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if (source[sn].sflags & SSPOT && |
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spotout(&sr, source[sn].sl.s)) |
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continue; /* outside spot */ |
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rayorigin(&sr, NULL, SHADOW, 1.0); |
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sr.rsrc = sn; |
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rayvalue(&sr); /* compute value */ |
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if (bright(sr.rcol) <= FTINY) |
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continue; /* missed/blocked */ |
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/* modify pixel */ |
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if (zbf[y-y0] != NULL && |
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sr.rt < zbf[y-y0][x-x0]) |
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zbf[y-y0][x-x0] = sr.rt; |
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pa = poly_area(ppoly, npv); |
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scalecolor(sr.rcol, pa*xr*yr); |
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scalecolor(pic[y-y0][x-x0], (1.-pa*xr*yr)); |
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addcolor(pic[y-y0][x-x0], sr.rcol); |
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} |
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} |
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} |
