star-sf

commit 10753a1d0273347d724a231060fa3737fb3c8893
parent 069846d48c0a19086eea3953008e9a1fa6797682
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Thu,  2 Mar 2017 11:48:22 +0100

Handle the total internal reflection for the thin specular dielectric BxDF

Diffstat:
M
src/ssf_thin_specular_dielectric.c
 | 
11
++++++-----
M
src/test_ssf_thin_specular_dielectric.c
 | 
8
++++++++

2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/src/ssf_thin_specular_dielectric.c b/src/ssf_thin_specular_dielectric.c
@@ -68,20 +68,21 @@ thin_specular_dielectric_sample
   double tau, tau_sqr;
   ASSERT(bxdf && rng && wi && N && wo);
   ASSERT(d3_is_normalized(wo) && d3_is_normalized(N));
+  ASSERT(d3_dot(wo, N) > -1.e-6);
   (void)rng;
 
   eta = bsdf->eta_i / bsdf->eta_t;
-  if(!refract(wt, wo, N, eta)) {
-    d3_splat(wi, 0); /* TODO handle this case */
-    return 0;
+  if(!refract(wt, wo, N, eta)) { /* Total internal reflection */
+    reflect(wi, wo, N);
+    return 1;
   }
   fresnel = bsdf->fresnel;
 
-  cos_wo_N = d3_dot(wo, N);
+  cos_wo_N = MMAX(0.0, d3_dot(wo, N));
   SSF(fresnel_dielectric_dielectric_setup(fresnel, bsdf->eta_i, bsdf->eta_t));
   rho1 = ssf_fresnel_eval(fresnel, cos_wo_N);
 
-  cos_wt_N = d3_dot(wt, d3_minus(tmp, N));
+  cos_wt_N = MMAX(0.0, d3_dot(wt, d3_minus(tmp, N)));
   SSF(fresnel_dielectric_dielectric_setup(fresnel, bsdf->eta_t, bsdf->eta_i));
   rho2 = ssf_fresnel_eval(fresnel, cos_wt_N);
 
diff --git a/src/test_ssf_thin_specular_dielectric.c b/src/test_ssf_thin_specular_dielectric.c
@@ -101,6 +101,14 @@ main(int argc, char** argv)
   CHECK(IS_INF(pdf), 1);
   CHECK(d3_eq_eps(wi, d3(tmp, -wo[0], wo[1], 0), 1.e-6), 1);
 
+  /* Check total internal reflection, i.e. no transmission */
+  d3_normalize(wo, d3(wo, 1, 0.0000001, 0));
+  /*CHECK(ssf_thin_specular_dielectric_setup(bsdf, 0, 1.4, 1.0, 1), RES_OK);*/
+  R = ssf_bxdf_sample(bsdf, rng, wo, N, wi, &pdf);
+  NCHECK(R, 0);
+  CHECK(IS_INF(pdf), 1);
+  CHECK(d3_eq_eps(wi, d3(tmp, -wo[0], wo[1], 0), 1.e-6), 1);
+
   wo[0] = ssp_rng_uniform_double(rng, -1, 1);
   wo[1] = ssp_rng_uniform_double(rng, -1, 1);
   wo[2] = ssp_rng_uniform_double(rng, -1, 1);