Add dielectric reflectiveness (using Schlick's Approximation).

1 files changed, 11 insertions, 0 deletions

diff --git a/material_dielectric.h b/material_dielectric.h
index 48382b4..46b17da 100644
--- a/material_dielectric.h
+++ b/material_dielectric.h
@@ -10,8 +10,19 @@
 
 class material_dielectric : public material {
     double ri_inv;
+
+    static double reflectance(double cosine, double ref_idx) {
+        assert(cosine > 0);
+        assert(ref_idx > 0);
+        // Use Schlick's approximation for reflectance.
+        auto r0 = (1 - ref_idx) / (1 + ref_idx);
+        r0 = r0 * r0;
+        return r0 + (1 - r0) * pow((1 - cosine), 5);
+    }
+
 public:
     explicit material_dielectric(double ri) : ri_inv{1.0 / ri} {}
+
     bool scatter(ray3d &r, const object &hit_obj, double hit_t, random_uv_gen_3d &ruvg) const override;
 };