I am currently working on constructing a sensible 2D engine using Visual C++. One of my goals is to have the engine be re-usable and easy. I currently have the following classes (well, these are the relevant ones): Texture //a texture to be applied to an Object2D Object2D //a better name for this would have been Polygon AffineTransform //rotations, translations, etc. Matrix3x3 //3x3 matrix math. World //a collection of entities in world-space. Entity //a collection of objects. I''m having a few problems coming up with a sensible solution of getting an object from object-space onto the screen. Logically, it makes sense to have the world as a collection of entities (eg. the "world" is every entity currently existing.) IF this is done, everything works fine except I end up with a slow bottle neck when I go from world-space to view-space. (eg. clipping the world so it fits on the screen. I''m probably misusing some 3d lingo here, but basically world-space ->viewspace -> screen is pretty much all one step) The problem is, short of testing every entity (which would then involve testing every Object2D (polygon) ), how do I determine which objects are visible? I was thinking of calling a refreshVisibile() function to test everything and determining the visible entities. Then, I would only need to test an object if it is moved (to see if it''s gone off or on the screen.) Does this sound like a reasonable approach? Basically, I know how to do it slowly, but i''m not sure how to do it quickly. Are there ANY object oriented 2D engines out there?