I want to point out few thing with your code.
First of all, please don't take my remarks personally, this is only for your improvement.
1. General project structure.
You mixed concers everywhere project structure can be improved much.
For example, you should split concers between different modules of the game.
You should put everything related to engine in the engine folder, like low level modules related to rendering, video playback, audio, input, memory, your funny string library and whatsoever, and everything, related to the high-level stuff like the gameplay, page display, in the gameplay folder.
I'm also surprised, that all gameplay related stuff is just put into a single code file named dce-main.c, you should've splitted the concerns into modules or classes, or separate files at least.
Main.c typically should contain stuff like
int main()
{
while(true)
{
initMemory();
readInput();
runEngine();
}
}
and not much bigger then that.
2. Architecture.
I would suggest reading books like GoF, Game Programing Patterns and Game Engine Architecture by jason gregory at first.
http://gameprogrammingpatterns.com/contents.html
https://en.wikipedia.org/wiki/Design_Patterns
https://www.amazon.com/Engine-Architect ... 1138035459
I'm not advocating OOP, as much as I grew to dislike this approach in software engineering later these days, nevertheless, it's still a domineering approach.
Then I heavily recomment to take a look at what Entity Component system is.
https://medium.com/ingeniouslysimple/en ... c31464240d
Basically you have an Entity which is a simple integer Id and it has associated data and code containers to it, which you inject the data and code components at runtime based of the desciption in some DSL language (xml or whatever).
Basically it means you'll have different entites in your game, like MainPlayer, Enemy, MainMenu, SoundManager, GameStateManager.
You assign (dependecny inject) data containers to them, like what data would they have at runtime - for example, SoundManager will have string array with all four CDDA track paths linked to it. Enemy will have 3d model, animation graph.
Then you add code components to it - like CollisionChecker3D, EnemyAI, whatever, and of course gameplay logic script, which will read the input, state of the level, and do some appropriate actions based on it - move enemies, shoew screens, will launch music (or better delegate this call to MainLevelState component), and etc.
I also dislike code parts like:
sprintf(str, "O\n");
DCE_PrintString(str, 312, 232);
sprintf(str, "%i / %i\n", player->clip, player->ammo);
DCE_RenderCompileAndSubmitHeader(NULL);
DCE_RenderTexturedQuad2D(500, 480-32, 500 + strlen(str) * 8, 480-16, 0, 0, 0, 0, 0xD0505050);
DCE_PrintString(str, 500, 480 - 32);
}
else
{
float x = 572, y;
if(index == 0)
{
y = 224 - 56;
sprintf(str, "O\n");
DCE_PrintString(str, 312, 104);
}
else
{
y = 480 - 56;
sprintf(str, "O\n");
DCE_PrintString(str, 312, 344);
}
I understand, that it's related to UI, but it has a lot of magic constants and stuff like this should go into "data" part as much as possible, into .xml files or whatever format, which can be edited with level editor or just code-editor, whatever.
Variable naming also can be improved.
What also makes thing messy is how rendering, audio, and all systems are basically mixed into one file and one function call, concerns should really be separated.
I understand it was your hobby project, just in case you wish to imrove at craft of making games.
