star-sf

commit 941277a1bc97837d22befd804c6de6368f099cb8
parent 8621fd538153443dd896cf59a3dffb07a8c94595
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Wed, 28 Sep 2016 19:09:12 +0200

Remove the reflectivity parameter from the microfacet BRDF

Diffstat:
M
src/ssf.h
 | 
1
-
M
src/ssf_microfacet_reflection.c
 | 
12
+++---------
M
src/test_ssf_microfacet_reflection.c
 | 
46
+++++++++++++++++++---------------------------

3 files changed, 22 insertions(+), 37 deletions(-)
diff --git a/src/ssf.h b/src/ssf.h
@@ -295,7 +295,6 @@ ssf_lambertian_reflection_setup
 res_T
 ssf_microfacet_reflection_setup
   (struct ssf_bxdf* data,
-   const double reflectivity,
    struct ssf_fresnel* fresnel,
    struct ssf_microfacet_distribution* distrib);
 
diff --git a/src/ssf_microfacet_reflection.c b/src/ssf_microfacet_reflection.c
@@ -20,7 +20,6 @@
 #include <rsys/double3.h>
 
 struct microfacet_reflection {
-  double reflectivity;
   struct ssf_fresnel* fresnel;
   struct ssf_microfacet_distribution* distrib;
 };
@@ -34,7 +33,6 @@ microfacet_reflection_init(struct mem_allocator* allocator, void* data)
   struct microfacet_reflection* bxdf = data;
   ASSERT(bxdf);
   (void)allocator;
-  bxdf->reflectivity = 0.0;
   bxdf->fresnel = NULL;
   bxdf->distrib = NULL;
   return RES_OK;
@@ -76,7 +74,7 @@ microfacet_reflection_eval
   G = MMIN((2*cos_wh_N*cos_wo_N)/cos_wh_wo, (2*cos_wh_N*cos_wi_N)/cos_wh_wo);
   G = MMIN(1, G);
 
-  return bxdf->reflectivity * F*D*G/(4*cos_wi_N*cos_wo_N);
+  return F*D*G/(4*cos_wi_N*cos_wo_N);
 }
 
 static FINLINE double
@@ -103,8 +101,7 @@ microfacet_reflection_sample
   ssf_microfacet_distribution_sample(bxdf->distrib, u, v, wo, N, wh, &pdf_wh);
   reflect(dir, wo, wh);
   *pdf = pdf_wh / (4.0*fabs(d3_dot(wo, wh))); /* TODO check this */
-  if(d3_dot(dir, N) <= 0.0) return 0.0;
-  R = microfacet_reflection_eval(bxdf, wo, N, dir);
+  R = d3_dot(dir, N) > 0 ? microfacet_reflection_eval(bxdf, wo, N, dir) : 0;
   d3_set(wi, dir);
   return R;
 }
@@ -149,19 +146,16 @@ const struct ssf_bxdf_type ssf_microfacet_reflection = {
 res_T
 ssf_microfacet_reflection_setup
   (struct ssf_bxdf* bxdf,
-   const double reflectivity,
    struct ssf_fresnel* fresnel,
    struct ssf_microfacet_distribution* distrib)
 {
   struct microfacet_reflection* microfacet;
-  if(!bxdf || reflectivity < 0 || reflectivity > 1 || !fresnel || !distrib)
+  if(!bxdf || !fresnel || !distrib)
     return RES_BAD_ARG;
   if(!BXDF_TYPE_EQ(&bxdf->type, &ssf_microfacet_reflection))
     return RES_BAD_ARG;
 
   microfacet = bxdf->data;
-  microfacet->reflectivity = reflectivity;
-
   if(microfacet->fresnel != fresnel) {
     if(microfacet->fresnel) SSF(fresnel_ref_put(fresnel));
     SSF(fresnel_ref_get(fresnel));
diff --git a/src/test_ssf_microfacet_reflection.c b/src/test_ssf_microfacet_reflection.c
@@ -38,48 +38,39 @@ main(int argc, char** argv)
   mem_init_proxy_allocator(&allocator, &mem_default_allocator);
   CHECK(ssf_bxdf_create(&allocator, &ssf_microfacet_reflection, &bxdf), RES_OK);
   CHECK(ssf_bxdf_create(&allocator, &bxdf_dummy, &dummy), RES_OK);
-  CHECK(ssf_fresnel_create
-    (&allocator, &ssf_fresnel_dielectric_dielectric, &F), RES_OK);
+  CHECK(ssf_fresnel_create(&allocator, &ssf_fresnel_no_op, &F), RES_OK);
   CHECK(ssf_microfacet_distribution_create
     (&allocator, &ssf_beckmann_distribution, &D), RES_OK);
 
-  CHECK(ssf_beckmann_distribution_setup(D, 0.7), RES_OK);
+  CHECK(ssf_beckmann_distribution_setup(D, 0.9), RES_OK);
 
-  CHECK(ssf_fresnel_dielectric_dielectric_setup(F, 0.7, 1.3), RES_OK);
-
-  CHECK(ssf_microfacet_reflection_setup(NULL, -1, NULL, NULL), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, -1, NULL, NULL), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(NULL, 0.123, NULL, NULL), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, 0.123, NULL, NULL), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(NULL, -1, F, NULL), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, -1, F, NULL), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(NULL, 0.123, F, NULL), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, 0.123, F, NULL), RES_BAD_ARG);
-
-  CHECK(ssf_microfacet_reflection_setup(NULL, -1, NULL, D), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, -1, NULL, D), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(NULL, 0.123, NULL, D), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, 0.123, NULL, D), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(NULL, -1, F, D), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, -1, F, D), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(NULL, 0.123, F, D), RES_BAD_ARG);
-  CHECK(ssf_microfacet_reflection_setup(bxdf, 0.123, F, D), RES_OK);
+  CHECK(ssf_microfacet_reflection_setup(NULL, NULL, NULL), RES_BAD_ARG);
+  CHECK(ssf_microfacet_reflection_setup(bxdf, NULL, NULL), RES_BAD_ARG);
+  CHECK(ssf_microfacet_reflection_setup(NULL, F, NULL), RES_BAD_ARG);
+  CHECK(ssf_microfacet_reflection_setup(bxdf, F, NULL), RES_BAD_ARG);
+  CHECK(ssf_microfacet_reflection_setup(NULL, NULL, D), RES_BAD_ARG);
+  CHECK(ssf_microfacet_reflection_setup(bxdf, NULL, D), RES_BAD_ARG);
+  CHECK(ssf_microfacet_reflection_setup(NULL, F, D), RES_BAD_ARG);
+  CHECK(ssf_microfacet_reflection_setup(bxdf, F, D), RES_OK);
 
   /* Numerically evaluate rho */
   d3(N, 0, 1, 0);
-  d3_normalize(wo, d3(wo, rand_canonic(), rand_canonic(), rand_canonic()));
   sum = sum_sqr = 0;
+  ran_hemisphere_cos(N, wo, NULL);
   FOR_EACH(i, 0, NSTEPS) {
-    const double u = rand_canonic();
-    const double v = rand_canonic();
-    const double R = ssf_bxdf_sample(bxdf, u, v, wo, N, wi, &pdf);
-    const double weight = R * d3_dot(wi, N) / pdf;
+    double R;
+    double weight;
+    ran_hemisphere_cos(N, wi, &pdf);
+    R = ssf_bxdf_eval(bxdf, wo, N, wi);
+    weight = R * d3_dot(wi, N) / pdf;
     sum += weight;
     sum_sqr += weight*weight;
   }
+
   E = sum / (double)NSTEPS;
   V = sum_sqr / (double)NSTEPS - E*E;
   SE = sqrt(V/(double)NSTEPS);
+  printf("%g +/- %g\n", E, SE);
   CHECK(eq_eps(E, ssf_bxdf_rho(bxdf, wo, N), SE), 1);
 
   CHECK(ssf_bxdf_ref_put(bxdf), RES_OK);
@@ -92,3 +83,4 @@ main(int argc, char** argv)
   CHECK(mem_allocated_size(), 0);
   return 0;
 }
+