libgdx如何存储数据以进行碰撞检测

Question

I am developing a game using libgdx scene2d. All my objects are subclasses of Actor (we call them GameObject ), so they allready have position and size, but all in separate fields ( float x; float y; float height; float width;) . For collision detection i use some self made methods, but also some methods of Intersector . The Intersector methods need Vector2 parameters for position and size. So i have to create Vector2 objects out of the Actor s fields, every render cycle . And this is bad for garbage collection. My only idea to avoid this is to have a Vector2 position and Vector2 size in my GameObject s. But then i have redundant data and I would need to override the getter and setter methods to update the Vector2 and the Actor s data (needed for drawing). Is there another, better way? Is redundant data better then the problem with the garbage? Or should i copy the Intersector s methods and edit them to use float x and float y instead of Vector2 ?

Answer 1

LibGdx has a nice Pools class, so why don't you use it?

Here is an example:

Vector2 position = Pools.obtain(Vector2.class);
// use your Vector2 for something
Pools.free(position);

You will not have any redundant data, it will still be fast and much more predictable than having objects unnecessarily allocated on each frame.

My 2 cents:

I agree that premature optimization is a bad idea, but in my experience it is beneficial to take certain design approaches when making certain types of applications.

Specifically, I believe it is a good idea to avoid unnecessary object allocations on each frame when making games, especially for platforms such as Android.

These allocation might not be a problem now, or for some specific devices, but it might come back and bite you in the ass, and you might be forced to do some non-trivial changes to your code - this has happened to me.

Answer 2

Redundant data are pretty bad as redundancy leads to time and memory overhead and also to programming errors. Modifying a third party method is bad as i means redoing it when it gets upgraded. Somehow all solutions are bad, but you should always measure it . Is the garbage a real problem?

I'd switch to using Vector2 everywhere, if possible. You could also recycle existing Vector and fill it with your data. This eliminates the garbage problem, but there's still the cost for copying.

The final solution is up to you. I doubt that anybody could say for sure what's best for you.