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root/radiance/ray/src/hd/rhdisp3.c
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Comparing ray/src/hd/rhdisp3.c (file contents):
Revision 3.9 by gregl, Tue Jan 6 15:08:50 1998 UTC vs.
Revision 3.10 by gwlarson, Tue Jul 7 11:07:42 1998 UTC

# Line 1 | Line 1
1 < /* Copyright (c) 1997 Silicon Graphics, Inc. */
1 > /* Copyright (c) 1998 Silicon Graphics, Inc. */
2  
3   #ifndef lint
4   static char SCCSid[] = "$SunId$ SGI";
# Line 19 | Line 19 | struct cellist {
19  
20  
21   int
22 < npixels(vp, hr, vr, hp, bi)     /* compute appropriate number to evaluate */
22 > npixels(vp, hr, vr, hp, bi)     /* compute appropriate nrays to evaluate */
23   register VIEW   *vp;
24   int     hr, vr;
25   HOLO    *hp;
# Line 27 | Line 27 | int    bi;
27   {
28          VIEW    vrev;
29          GCOORD  gc[2];
30 <        FVECT   cp[4], ip[4];
31 <        double  af, ab;
30 >        FVECT   cp[4], ip[4], pf, pb;
31 >        double  af, ab, sf2, sb2, dfb2, df2, db2, penalty;
32          register int    i;
33                                          /* compute cell corners in image */
34          if (!hdbcoord(gc, hp, bi))
35                  error(CONSISTENCY, "bad beam index in npixels");
36          hdcell(cp, hp, gc+1);           /* find cell on front image */
37 <        for (i = 0; i < 4; i++) {
37 >        for (i = 3; i--; )              /* compute front center */
38 >                pf[i] = 0.5*(cp[0][i] + cp[2][i]);
39 >        sf2 = 0.25*dist2(cp[0], cp[2]); /* compute half diagonal length */
40 >        for (i = 0; i < 4; i++) {       /* compute visible quad */
41                  viewloc(ip[i], vp, cp[i]);
42                  if (ip[i][2] < 0.) {
43                          af = 0;
# Line 48 | Line 51 | int    bi;
51                  (ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
52          af += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
53                  (ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
54 <        if (af >= 0) af *= 0.5;
52 <        else af *= -0.5;
54 >        af *= af >= 0 ? 0.5 : -0.5;
55   getback:
56          copystruct(&vrev, vp);          /* compute reverse view */
57          for (i = 0; i < 3; i++) {
# Line 59 | Line 61 | getback:
61                  vrev.vvec[i] = -vp->vvec[i];
62          }
63          hdcell(cp, hp, gc);             /* find cell on back image */
64 <        for (i = 0; i < 4; i++) {
64 >        for (i = 3; i--; )              /* compute rear center */
65 >                pb[i] = 0.5*(cp[0][i] + cp[2][i]);
66 >        sb2 = 0.25*dist2(cp[0], cp[2]); /* compute half diagonal length */
67 >        for (i = 0; i < 4; i++) {       /* compute visible quad */
68                  viewloc(ip[i], &vrev, cp[i]);
69 <                if (ip[i][2] < 0.)
70 <                        return((int)(af + 0.5));
69 >                if (ip[i][2] < 0.) {
70 >                        ab = 0;
71 >                        goto finish;
72 >                }
73                  ip[i][0] *= (double)hr; /* scale by resolution */
74                  ip[i][1] *= (double)vr;
75          }
# Line 71 | Line 78 | getback:
78                  (ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
79          ab += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
80                  (ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
81 <        if (ab >= 0) ab *= 0.5;
82 <        else ab *= -0.5;
83 <                                        /* round off smaller area */
84 <        if (af <= ab)
85 <                return((int)(af + 0.5));
86 <        return((int)(ab + 0.5));
81 >        ab *= ab >= 0 ? 0.5 : -0.5;
82 > finish:         /* compute penalty based on dist. sightline - viewpoint */
83 >        df2 = dist2(vp->vp, pf);
84 >        db2 = dist2(vp->vp, pb);
85 >        dfb2 = dist2(pf, pb);
86 >        penalty = dfb2 + df2 - db2;
87 >        penalty = df2 - 0.25*penalty*penalty/dfb2;
88 >        if (df2 > db2)  penalty /= df2 <= dfb2 ? sb2 : sb2*df2/dfb2;
89 >        else            penalty /= db2 <= dfb2 ? sf2 : sf2*db2/dfb2;
90 >        if (penalty < 1.) penalty = 1.;
91 >                                        /* round off smaller non-zero area */
92 >        if (ab <= FTINY || (af > FTINY && af <= ab))
93 >                return((int)(af/penalty + 0.5));
94 >        return((int)(ab/penalty + 0.5));
95   }
96  
97  

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