Gravity constant moved into constants.rb, camera can now report what it is looking at, entity has knowledge of camera now, AABB tree search can now use either BoundingBox or Ray colliders

lib/objects/entity.rb

@@ -7,7 +7,7 @@ class IMICFPS
 
     attr_accessor :scale, :visible, :renderable, :backface_culling
     attr_accessor :position, :rotation, :velocity
-    attr_reader :name, :debug_color, :bounding_box, :collision, :physics, :mass, :drag
+    attr_reader :name, :debug_color, :bounding_box, :collision, :physics, :mass, :drag, :camera
 
     def initialize(x: 0, y: 0, z: 0, bound_model: nil, scale: MODEL_METER_SCALE, backface_culling: true, auto_manage: true, manifest_file: nil)
       @position = Vector.new(x, y, z)
@@ -43,6 +43,8 @@ class IMICFPS
         normalize_bounding_box
       end
 
+      @camera = nil
+
       return self
     end
 
@@ -70,6 +72,14 @@ class IMICFPS
       @bound_model = nil
     end
 
+    def attach_camera(camera)
+      @camera = camera
+    end
+
+    def detach_camera
+      @camera = nil
+    end
+
     def setup
     end