Easy And Accurate 2D Collisions
It is a simple process to perform box collisions in Cocoa Touch using the CGRectIntersectsRect function, and while this is easy and provides decent performance it does not make for the most accurate collisions.
A couple of new tutorials have been created featuring techniques for creating more accurate collisions methods.
The first tutorial is from 71 Squared on Collision Detection Methods which has a some nice straightforward functions written in C that you can drop into your code for Circle to Rectangle, and Circle to Circle collisions.
Adding A 2D Hud To A 3D OpenGL ES Scene
Drawing a 2D Hud on a 3D OpenGL ES scene is a common task when developing games.
To do this without any distortion in OpenGL ES you need to draw your HUD through a matrix different from the projection matrix used for 3D objects.
Jeff LaMarche, co-author of Beginning iPhone 3 Development, and More iPhone development has added a new tutorial on Drawing a Hud Display in OpenGL ES.
The Commercial iPhone Game Engine Comparison (3D and 2D)
After making my open source iphone game engine comparison post,, I’ve noticed quite a few searches for a comparison of commercial iPhone game engines, so I’ve decided to create this comparison.
Please note that this is only a feature comparison, as while I have tested out the editors of these engines (where available for free) I have tried all of these engines and have been maintaining this site for the last two years so I can provide a lot of information on the topics. I’ve listed them separately in 3D and 2D placing the free ones first.
11 Cocos2D iPhone Game Engine Resources
I mentioned the open source Cocos2D iPhone game engine on my list of iPhone game engines.
For those that don’t know Cocos2D is an open source LGPL licensed 2D game engine for the iPhone that has already been used in many games. Mitch Allen has posted a nice list of resources for the open source Cocos 2D iPhone game engine.
My favorites from the list are:
1. iPhone Dev – Which contains a collection of Cocos 2D tutorials for beginners.
iPhone Game Programming: CoreAnimation vs. OpenGL ES
I saw an interesting question being asked by an aspiring iPhone game developer, "Should I use CoreAnimation or OpenGL ES?".
Simple answer:
Core Animation is fine for games where performance is not critical, and for new programmers will likely be easy to use, OpenGL is needed for anything else.
Long Answer:
Core Animation utilizes OpenGL ES, it is high level, and in my testing works fine in situations where performance is critical.