Ios – Want to display a 3D model on the iPhone: how to get started?


I want to display and rotate a single 3D model, preferably textured, on the iPhone. Doesn't have to zoom in and out, or have a background, or anything.

I have the following:

  • an iPhone
  • a MacBook
  • the iPhone SDK
  • Blender

My knowledge base:

  • I can make 3D models in various 3D programs (I'm most comfortable with 3D Studio Max, which I once took a course on, but I've used others)
  • General knowledge of procedural programming from years ago (QuickBasic – I'm old!)
  • Beginner's knowledge of object-oriented programming from going through simple Java and C# tutorials (Head Start C# book and my wife's intro to OOP course that used Java)
  • I have managed to display a 3D textured model and spin it using a tutorial in C# I got off the net (I didn't just copy and paste, I understand basically how it works) and the XNA game development library, using Visual Studio on Windows.

What I do not know:

  • Much about Objective C
  • Anything about OpenGL or OpenGL ES, which the iPhone apparently uses
  • Anything about XCode

My main problem is that I don't know where to start! All the iPhone books I found seem to be about creating GUI applications, not OpenGL apps. I found an OpenGL book but I don't know how much, if any, applies to iPhone development. And I find the Objective C syntax somewhat confusing, with the weird nested method naming, things like "id" that don't make sense, and the scary thought that I have to do manual memory management.

Where is the best place to start? I couldn't find any tutorials for this sort of thing, but maybe my Google-Fu is weak. Or maybe I should start with learning Objective C? I know of books like Aaron Hillgrass', but I've also read that they are outdated and much of the sample code doesn't work on the iPhone SDK, plus it seems geared towards the Model-View-Controller paradigm which doesn't seem that suited for 3D apps.

Basically I'm confused about what my first steps should be.

Best Solution

Once again, if I may plug my own work, I have written a post about the things I've learned from developing an OpenGL ES application on the iPhone. That application, Molecules (referred to by frankodwyer), is open source and I have a writeup on some of the other tricky issues I ran into while developing it. The application generates 3-D models and lets you rotate and scale them with your fingers, which sounds close to your needs. You can download the code, compile it, and run it on your desktop in a matter of a few minutes. If you join the iPhone Developer Program, you can install it on your device.

When it comes to object loading, Bill Dudney is working on a Wavefront OBJ loader for the iPhone that might be able to take in your Blender files, should they be exportable in that format. I haven't done much texture work on the iPhone yet, but it sounds like his example has that working now.

Overall, I find that learning by example and by jumping into development of some small, targeted applications (that you may never release) are what works for me. Try tweaking the examples listed above and see what happens. You should be able to read through the Objective-C code in those examples and start to get a feel for what they're doing.

Even though Hillegass's book (the third edition just came out and is up-to-date) focuses on the Mac, the Cocoa fundamentals he teaches are still relevant for the iPhone. The MVC design pattern serves you just as well on the iPhone as the Mac. I actually deviated from that pattern in a few places within Molecules, and I regret that decision because those sections of the application became a mess. The book is an easy read and well worth your time.