Leadwerks on the iPhone
Entry posted by Josh ·
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So here's what it took to get Leadwerks running on the iPhone:
Let's start at the point we had the C++ code building and running with an OpenGL 1 renderer on OSX. I was worried OpenGLES might be a dramatically different API that required a whole new learning curve, but I was pleasantly surprised. It's just a stripped-down version of OpenGL, more like OpenGL 3.3 than anything else. Making the OpenGL2ES renderer was mostly just a copy and paste operation, and then I had to comment out a few unsupported commands.
Building for the iPhone simulator was a bit harder. The first problem I ran into was that file paths on iOS are case-sensitive. (They aren't on OSX.) This was problematic, because my asset management code stored file paths in lowercase, so that had to be changed.
Then there was the matter of setting the application's file path. A special function had to be written to set this at application startup.
The hardest part was the context handling. The flow of an iOS app all revolves around Objective-C events, and this doesn't mix well with a C++ program. What I ended up doing was creating an App class like this:
class App {
public:
bool Start();
bool Continue();
int Finish();
};
Objective-C calls these class functions to keep the program loop running. Once the Continue() function returns false, the application calls Finish() and exits.
I'm okay with using this same design across all platforms, if it means your C++ code will run on everything. of course, this is just a convention in the generated project files, and if you want you can code the engine with any program structure you want. This is just the best way to ensure your code runs on everything.
The last challenge was setting up the provisioning profiles, certificate, and some other stuff I don't even remember. This was pretty tricky, and took most of the day to figure out. In the end, I just ran through the instructions a second time, and it magically worked. 
At the end of all that, it was nice to see Leadwerks running on the iPhone. iOS was the hardest platform to add support for, and I don't expect the same difficulty when we add support for Android:
Thanks to Ed Upton and Simon Armstrong for their help and advice.
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