Using an existing C++ engine on the iPhone

Question

I come from a C/C++ background and more recently flash. Anyway I wrote a 2D engine in AS3 and would like to get it running on the iPhone. To start with I converted it to C++. As a test I wrote a very simple C++ engine and added the files to a standard view-based application in XCode. I then added a UIImageView that covered the whole iPhone screen.

The way my test engine is set up at the moment is that each frame it renders the result to an image which is then used to update the UIImageView every frame. Assuming I can pass input from the iPhone to the C++ engine this seems like a fairly platform-independent solution. Since I have been coding for iPhone/Mac for less than 1 day I was wondering whether this is the standard approach to getting an existing C++ engine running on the iPhone and if not, what is?

Thanks for any help, CG

Answer 1

Yes, that is a fairly normal way to handle it. Generally you would either use small Objective C stubs for your events and things like pushing out the frame, or you would setup an OpenGL context and then pass it to your C++ code.

Answer 2

There's no problem in you rendering into an image and refreshing that image, but you get no acceleration from the GPU using this technique. So you'd be burning a lot of CPU cycles, which in turns eats battery.

If the objects you are rendering can be described in normal graphics primitives, be sure to use the drawing APIs which are optimised for the platform and can delegate work to the GPU.

An alternative approach is to make use of OpenGLES, but this has a learning curve