71² – The ramblings of two 30-something developers

iPhone Game Development…

Flushed with getting my apps on the Apple App Store I decided to try my hand at writing a game on the iPhone.  I’ve done game development in Java as the Sudoku game I posted in an early post shows.  So given games seem to be very popular on the iPhone I’ve decided to give it a try.

Its a steep learning curve as I’m still new to Obj-C and now I’ve got to include OpenGL ES.  All my Java games were built on top of LWJGL which is an OpenGL wrapper for Java, but I also used a framework on top of that called Slick which removes you even further from the OpenGL side of things.

Nothing really exists like that for the iPhone which I have found, so I’m having to get to grips with OpenGL ES.  There are a lot of resources our there for OpenGL and I’ve found some for ES as well.  ES contains a reduced feature set so whilst a lot of standard OpenGL will work ok, there is a lot that wont.  OpenGL ES does not support glBegin, glEnd or GL_QUADS for example….still learning what they do anyway ;o)

So where have I got to…well I started by checking out the CrashLanding example app which Apple provide.  This is a simple game but provides a HUGE amount of clues as to how to put things on the screen and generally get an OpenGL app up and running.  I spent some time taking this example apart to see how it works and then trying some of my own code within it.  This took some time but I ended up having a reasonable idea of how it worked.

I then created my own project using the OpenGL ES App template in Xcode.  I then copied over the classes from the Crash Landing app which I needed.  These include the sound engine for playing your game sounds (which I had already used in iServant Bell) and also a convenience class called MyEAGLView.  This takes a UIView and places OpenGL specific functions within it for switching buffers etc so plenty of the deeper elements I don’t need to worry about at the moment.

I also took a copy of their Texture2D class.  This allows you to take a UIImage or some text and turn it into an OpenGL texture and then render it to the screen.  This is a great little class and works well.  I’ve added to this myself which I’ll go through in a later post.

Having done all of this I now have a framework in which I can start to develop my first game.  Currently I have got my own ship moving around the screen using the accelerometers and also have it firing when you tap the screen.  This has been much easier than I thought and I’m now starting to create more framework type functions so I can add animation etc.

I’m thinking that I will share my code and create some tutorials to follow what I am doing.  If anyone thinks this would be useful just drop in a comment. Below is a small video of what I’ve got so far. I’m working on getting the basics needed to make a game and then I’ll work more on the game concept and graphics etc.

Mike

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