Add min_weight property to Scene

src/scene.cc

@@ -19,6 +19,7 @@
 Scene::Scene()
     : width(640), height(480),
       max_depth(5),
+      min_weight(1e-4),
       ambient(new AmbientLight()),
       shapes(),
       lights(),
@@ -181,7 +182,7 @@ Scene::trace_ray(const Ray &ray,
                  const int depth,
                  const float weight)
 {
-    if (depth >= max_depth) {
+    if (depth >= max_depth || weight <= min_weight) {
         return Color::Black;
     }
 

src/scene.h

@@ -47,8 +47,12 @@ private:
     // Pixel dimensions of the image.
     int width, height;
 
-    // Ray tracing parameters.
+    /*
+     * Ray tracing parameters. max_depth indicates the maximum depth of the ray tree. min_weight indicates the minimum
+     * specular weight to apply before giving up.
+     */
     int max_depth;
+    float min_weight;
 
     // Scene objects.
     AmbientLight *ambient;