Basic functional raytracer

vec3.hpp

@@ -188,4 +188,22 @@ vec3 reflect(const vec3& v, const vec3 n)
     return v - 2*dot(v,n)*n;
 }
 
+vec3 refract (const vec3& uv, const vec3& n, double etai_over_etat)
+{
+    double cos_theta = fmin(dot(-uv, n), 1.0);
+    vec3 r_out_perp = etai_over_etat * (uv + cos_theta*n);
+    vec3 r_out_parallel = -sqrt(fabs(1.0 - r_out_perp.length_squared())) * n;
+    return r_out_perp + r_out_parallel;
+}
+
+vec3 random_in_unit_disk()
+{
+    while (true)
+    {
+        auto p = vec3(random_double(-1,1), random_double(-1,1), 0);
+        if (p.length_squared() >= 1) continue;
+        return p;
+    }
+}
+
 #endif