solstice-solver

commit df14b2c60b327164f71f0ce73de87849977923ef
parent 56d72fdef2d5755e21f4d511c770940415694516
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Tue, 18 Apr 2017 13:33:35 +0200

Do not reject sample the bounce directions in the path tracer

If the sample direction does not point on the right surface side wrt the
sampled BSDF component, set the radiative path weight to zero.

Diffstat:
M
src/ssol_draw_pt.c
 | 
29
+++++++++++------------------

1 file changed, 11 insertions(+), 18 deletions(-)
diff --git a/src/ssol_draw_pt.c b/src/ssol_draw_pt.c
@@ -150,9 +150,6 @@ Li(struct ssol_scene* scn,
   enum ssol_side_flag side;
   int russian_roulette = 0;
   int type;
-  int reject_sample;
-  int nfailures;
-  const int MAX_FAILURES = 10;
   res_T res = RES_OK;
   ASSERT(scn && view && org && dir && val);
 
@@ -230,22 +227,18 @@ Li(struct ssol_scene* scn,
     }
 
     /* Sampling a bounce direction */
-    nfailures = 0;
-    do {
-      reject_sample = 0;
-      R = ssf_bsdf_sample(ctx->bsdf, ctx->rng, wo, frag.Ns, wi, &type, &pdf);
-      ASSERT(0 <= R && R <= 1);
-      cos_wi_Ng = d3_dot(wi, frag.Ng);
-      if(((type & SSF_TRANSMISSION) && cos_wi_Ng > 0)
-      || ((type & SSF_REFLECTION)   && cos_wi_Ng < 0)) {
-        /* Reject inconsistent direction due to normal perturbation exepted if
-         * no other direction can be generated */
-        R = 0;
-        reject_sample = (++nfailures < MAX_FAILURES && !(type & SSF_SPECULAR));
-      }
-    } while(reject_sample);
-    f3_set_d3(ray_dir, wi);
+    R = ssf_bsdf_sample(ctx->bsdf, ctx->rng, wo, frag.Ns, wi, &type, &pdf);
+    ASSERT(0 <= R && R <= 1);
+
+    /* Due to the shading normal, the sampled direction may point in the wrong
+     * direction wrt the sampled BSDF component. */
+    cos_wi_Ng = d3_dot(frag.Ng, wi);
+    if((cos_wi_Ng > 0 && (type & SSF_TRANSMISSION))
+    || (cos_wi_Ng < 0 && (type & SSF_REFLECTION))) {
+      R = 0;
+    }
 
+    f3_set_d3(ray_dir, wi);
     if(type & SSF_TRANSMISSION) material_get_next_medium(mtl, &medium, &medium);
 
     if(!russian_roulette) {