use Lambertian reflection

src/main/java/eu/jonahbauer/raytracing/render/Camera.java

@@ -134,10 +134,7 @@ public final class Camera {
         if (optional.isPresent()) {
             var result = optional.get();
 
-            var newDirection = Vec3.random(true);
+            var newDirection = result.normal().plus(Vec3.random(true));
-            if (result.normal().times(newDirection) < 0) {
-                newDirection = newDirection.times(-1);
-            }
             var scattered = new Ray(result.position(), newDirection);
 
             return Color.lerp(Color.BLACK, getColor(scene, scattered, depth - 1), 0.5);