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root/radiance/ray/src/rt/m_bsdf.c
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Comparing ray/src/rt/m_bsdf.c (file contents):
Revision 2.34 by greg, Mon May 15 22:50:33 2017 UTC vs.
Revision 2.36 by greg, Tue May 16 20:06:40 2017 UTC

# Line 23 | Line 23 | static const char RCSid[] = "$Id$";
23   *  (opposite the surface normal) to bypass any intervening geometry.
24   *  Translation only affects scattered, non-source-directed samples.
25   *  A non-zero thickness has the further side-effect that an unscattered
26 < *  (view) ray will pass right through our material if it has any
27 < *  non-diffuse transmission, making the BSDF surface invisible.  This
28 < *  shows the proxied geometry instead. Thickness has the further
29 < *  effect of turning off reflection on the hidden side so that rays
30 < *  heading in the opposite direction pass unimpeded through the BSDF
26 > *  (view) ray will pass right through our material, making the BSDF
27 > *  surface invisible and showing the proxied geometry instead. Thickness
28 > *  has the further effect of turning off reflection on the reverse side so
29 > *  rays heading in the opposite direction pass unimpeded through the BSDF
30   *  surface.  A paired surface may be placed on the opposide side of
31   *  the detail geometry, less than this thickness away, if a two-way
32   *  proxy is desired.  Note that the sign of the thickness is important.
# Line 36 | Line 35 | static const char RCSid[] = "$Id$";
35   *  hides geometry in front of the surface when rays hit from behind,
36   *  and applies only the transmission and backside reflectance properties.
37   *  Reflection is ignored on the hidden side, as those rays pass through.
38 + *      When thickness is set to zero, shadow rays will be blocked unless
39 + *  a BTDF has a strong "through" component in the source direction.
40 + *  A separate test prevents over-counting by dropping specular & ambient
41 + *  samples that are too close to this "through" direction.  The same
42 + *  restriction applies for the proxy case (thickness != 0).
43   *      The "up" vector for the BSDF is given by three variables, defined
44   *  (along with the thickness) by the named function file, or '.' if none.
45   *  Together with the surface normal, this defines the local coordinate
# Line 43 | Line 47 | static const char RCSid[] = "$Id$";
47   *      We do not reorient the surface, so if the BSDF has no back-side
48   *  reflectance and none is given in the real arguments, a BSDF surface
49   *  with zero thickness will appear black when viewed from behind
50 < *  unless backface visibility is off.
50 > *  unless backface visibility is on, when it becomes invisible.
51   *      The diffuse arguments are added to components in the BSDF file,
52   *  not multiplied.  However, patterns affect this material as a multiplier
53   *  on everything except non-diffuse reflection.
# Line 59 | Line 63 | static const char RCSid[] = "$Id$";
63   /*
64   * Note that our reverse ray-tracing process means that the positions
65   * of incoming and outgoing vectors may be reversed in our calls
66 < * to the BSDF library.  This is fine, since the bidirectional nature
66 > * to the BSDF library.  This is usually fine, since the bidirectional nature
67   * of the BSDF (that's what the 'B' stands for) means it all works out.
68   */
69  
# Line 72 | Line 76 | typedef struct {
76          RREAL   toloc[3][3];    /* world to local BSDF coords */
77          RREAL   fromloc[3][3];  /* local BSDF coords to world */
78          double  thick;          /* surface thickness */
79 <        COLOR   cthru;          /* through component multiplier */
79 >        COLOR   cthru;          /* "through" component multiplier */
80          SDData  *sd;            /* loaded BSDF data */
81          COLOR   rdiff;          /* diffuse reflection */
82          COLOR   tdiff;          /* diffuse transmission */
# Line 80 | Line 84 | typedef struct {
84  
85   #define cvt_sdcolor(cv, svp)    ccy2rgb(&(svp)->spec, (svp)->cieY, cv)
86  
87 < /* Compute through component color */
87 > /* Compute "through" component color */
88   static void
89   compute_through(BSDFDAT *ndp)
90   {
# Line 130 | Line 134 | compute_through(BSDFDAT *ndp)
134                  tdir[0] = -ndp->vray[0] + dir2check[i][0]*srchrad;
135                  tdir[1] = -ndp->vray[1] + dir2check[i][1]*srchrad;
136                  tdir[2] = -ndp->vray[2];
137 <                if (normalize(tdir) == 0)
134 <                        continue;
137 >                normalize(tdir);
138                  ec = SDevalBSDF(&sv, tdir, ndp->vray, ndp->sd);
139                  if (ec)
140                          goto baderror;
# Line 148 | Line 151 | compute_through(BSDFDAT *ndp)
151                  goto baderror;
152          if (tomega > 1.5*dfp->minProjSA)
153                  return;                         /* not really a peak? */
154 <        if ((bright(vpeak) - ndp->sd->tLamb.cieY*(1./PI))*tomega <= .001)
155 <                return;                         /* < 0.1% transmission */
154 >        if ((bright(vpeak) - ndp->sd->tLamb.cieY*(1./PI))*tomega <= .007)
155 >                return;                         /* < 0.7% transmission */
156          for (i = 3; i--; )                      /* remove peak from average */
157                  colval(vsum,i) -= colval(vpeak,i);
158          --nsum;
# Line 184 | Line 187 | direct_specular_OK(COLOR cval, FVECT ldir, double omeg
187   {
188          int     nsamp, ok = 0;
189          FVECT   vsrc, vsmp, vjit;
190 <        double  tomega;
190 >        double  tomega, tomega2;
191          double  sf, tsr, sd[2];
192          COLOR   csmp, cdiff;
193          double  diffY;
# Line 249 | Line 252 | direct_specular_OK(COLOR cval, FVECT ldir, double omeg
252                          multisamp(sd, 2, (i + frandom())/(double)nsamp);
253                          vsmp[0] += (sd[0] - .5)*sf;
254                          vsmp[1] += (sd[1] - .5)*sf;
255 <                        if (normalize(vsmp) == 0) {
253 <                                --nsamp;
254 <                                continue;
255 <                        }
255 >                        normalize(vsmp);
256                  }
257                  bsdf_jitter(vjit, ndp, tsr);
258 <                                        /* compute BSDF */
258 >                                        /* check for variable resolution */
259 >                ec = SDsizeBSDF(&tomega2, vjit, vsmp, SDqueryMin, ndp->sd);
260 >                if (ec)
261 >                        goto baderror;
262 >                if (tomega2 < .12*tomega)
263 >                        continue;       /* not safe to include */
264 >                                        /* else compute BSDF */
265                  ec = SDevalBSDF(&sv, vjit, vsmp, ndp->sd);
266                  if (ec)
267                          goto baderror;
268 <                if (sv.cieY - diffY <= FTINY) {
263 <                        addcolor(cval, cdiff);
268 >                if (sv.cieY - diffY <= FTINY)
269                          continue;       /* no specular part */
265 –                }
270                  cvt_sdcolor(csmp, &sv);
271                  addcolor(cval, csmp);   /* else average it in */
272                  ++ok;
# Line 271 | Line 275 | direct_specular_OK(COLOR cval, FVECT ldir, double omeg
275                  setcolor(cval, .0, .0, .0);
276                  return(0);              /* no valid specular samples */
277          }
278 <        sf = 1./(double)nsamp;
278 >        sf = 1./(double)ok;
279          scalecolor(cval, sf);
280                                          /* subtract diffuse contribution */
281          for (i = 3*(diffY > FTINY); i--; )

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