Elephants! First python + pygame game submitted to App Store :)
So, I managed to submit a “python” app to the App Store — “Elephants!” Here’s a few crazy things I had to work out to get things going:
- I found that ObjC doesn’t care much for C++ objects that do their own reference counting. To have a “Game” object at all, I had to use a pointer to my object instead of using my reference counting object. It seems that during some of the “magic” of ObjC it copies objects without calling any of the C++ copying methods, so reference counting gets killed.
- I ported a basic subset of pygame to tinypyC++ and made it work under openGL. I don’t have this available in my tinypyC++ repository because it takes a good deal of prep-work to use (isn’t out-of-the-box) so it wouldn’t be generally useful to anyone yet.
- I was able to get pause on call / resume working by saving the game state to a text file. Since tab-separated files are so easy to create and parse in python this seemed to be the easiest route to getting the project done.
- I learned a ton about C++ templates. I still haven’t even touched the tip of the iceberg, and I’m not sure I want to, but at least I’m getting the basics down and that seems to be enough for me to stumble through this project with.
You can check out my current progress at svn://www.imitationpickles.org/tinypy/branches/tinypy2 (in the tinypy/example folder you can check out a julia fractal demo. It also includes a mini pygame module that depends on SDL not OpenGL, so it actually works out-of-the-box.)
Here are some things I’ve been adding this week in preparation for my next project:
- I’ve added “weak pointers” .. Since reference counting has the problem of cyclic references never getting collected, I had to do this for some use-cases. In tinypyC++ weak pointers are just normal pointers, and if the object is collected, the pointer will be invalid, so be careful. They are created by doing stuff like “x = ptr(GameData())”
- I’ve added more C style types. I’ve got uint16, cstr, Array, etc. This all makes it possible for me to have a different kind of object – a struct in tinypyC++. The struct is meant to be a C oriented type that can be saved directly to disk. In Elephants I serialized via saving CSV data. In the future, if I keep all the game state in C struct type data, I can just use a single simple line like “open(‘data.txt’,’wb’).write(struct_dump(game_data)”
- I found that STL extensions include a “hash_map” which turns out to be about 2x as fast as the normal “map”. I’m using that now.
I’m not entirely sure how useful this project is going to be for anyone else, or even for me for that matter. But I think after my next game project I’ll have a much better feel for what the situation is. TinypyC++ has some real tradeoffs in terms of being a bit of a hybrid of C++ and of python. It doesn’t offer the full power of either language. But I’m doing my best to capture a middle ground between them that will make my life easier.