ft: 9: diffuse materials

src/camera.rs

@@ -12,6 +12,7 @@ pub struct Camera {
     image_width: u32,
     image_height: u32,
     anti_alias_rate: u32,
+    max_depth: u32,
     center: Vec3,
     pixel00_loc: Vec3,
     pixel_delta_u: Vec3,
@@ -45,6 +46,7 @@ impl Camera {
             image_width: image_width,
             image_height: image_height,
             anti_alias_rate: anti_alias_rate,
+            max_depth: 50,
             center: camera_center,
             pixel00_loc: pixel00_loc,
             pixel_delta_u: pixel_delta_u,
@@ -70,7 +72,7 @@ impl Camera {
                             + (y * self.pixel_delta_v / (self.anti_alias_rate + 1) as f32);
                         let ray_dir = pixel_loc - self.center;
                         let r = Ray::new(self.center, ray_dir);
-                        pixel_colour += self.ray_colour(&hittables, &r);
+                        pixel_colour += self.ray_colour(&hittables, &r, self.max_depth);
                     }
                 }
 
@@ -84,11 +86,15 @@ impl Camera {
         imgbuf.save("output.png").unwrap();
     }
 
-    fn ray_colour<T: Hittable>(&self, hittables: &Vec<T>, r: &Ray) -> Colour {
+    fn ray_colour<T: Hittable>(&self, hittables: &Vec<T>, r: &Ray, depth: u32) -> Colour {
+        if depth <= 0 {
+            return Colour::nil();
+        }
+
         let closest = Hit::hit_list(hittables, r);
         if let Some(hit) = closest {
-            let n = hit.n();
-            return 0.5 * Colour::new(n.x() + 1., n.y() + 1., n.z() + 1.);
+            let dir = *hit.n() + Vec3::random_unit_hemisphere(hit.n());
+            return 0.5 * self.ray_colour(hittables, &Ray::new(*hit.p(), dir), depth - 1);
         }
 
         // background