Refraction is fully there, with magic fresnel!

source/include/intersection.h

@@ -23,6 +23,32 @@ struct Computation
           object(object), t(t), hitPoint(point), eyeVector(eyev), normalVector(normalv), inside(inside),
           overHitPoint(overHitP), underHitPoint(underHitP), reflectVector(reflectV), n1(n1), n2(n2) { };
 
+    double schlick()
+    {
+        /* Find the cos of the angle betzeen the eye and normal vector */
+        double cos = this->eyeVector.dot(this->normalVector);
+        double r0;
+        /* Total internal reflection can only occur when n1 > n2 */
+        if (this->n1 > this->n2)
+        {
+            double n, sin2_t;
+            n = this->n1 / this->n2;
+            sin2_t = (n * n) * (1.0 - (cos * cos));
+            if (sin2_t > 1.0)
+            {
+                return 1.0;
+            }
+            /* Compute the cos of theta */
+            cos = sqrt(1.0 - sin2_t);
+        }
+
+
+        r0 = ((this->n1 - this->n2) / (this->n1 + this->n2));
+        r0 = r0 * r0;
+
+        return r0 + (1 - r0) *  ((1 - cos)*(1 - cos)*(1 - cos)*(1 - cos)*(1 - cos));
+    };
+
     Shape *object;
     double t;
     Tuple hitPoint;