Spaceship Flying In Space

Back in college, before I knew much about anything, I gave a resume to a tiny little company called HDC Computer Corporation. That name kind of pegged them (constrained them?) to be a Microsoft Windows development house.

They managed to get some of their stuff bundled into Windows-286, if I recall correctly, including a little space shooter game called "HDC Rocks". Yes, it was about shooting rocks in space. Also, the title was a gag and tongue-in-cheek motto.

The Internet doesn't seem to remember that little nugget, but maybe it will now.

What you see here is the rebuilt version of as far as I had got on my "Space Rocks" demo - a little space ship moving around on the screen, rendering in OpenGL 2.1, with a window provided by SDL2.

Nothing's particularly exciting about it - the pathfinding, if you can call it that, is "move horizontally, then move vertically". There's no real obstacles. It doesn't have a lose condition.

But it's running again, OpenGL commands, as issued from my language, sent through a C shim to a vanilla OpenGL implementation.

As I mentioned in my previous post, I had lost a file (failed to check in my work) called gl_tools.c, which contained that layer, so the effort necessary to reproduce it was simply(?) a matter of exporting GL calls down into my library.

Sort of. The time management code is coming from SDL, so that took a little more attention. The initialization of an OpenGL context isn't quite as simple as I had recalled. I made use of Lazy Foo' Productions' SDL/OpenGL tutorial to figure out what bits I really had to rebuild inside my shim library.

And there you go, it's working again. And checked in, besides.

I even made myself a little convenience tool that launches the program, records frames of it rendering, then compresses that into an animated GIF all in one handy script. I could make it slightly cleverer, by forcing the window to open up at a particular point on the desktop, which would keep you from looking at my emacs window in the background. But maybe emacs makes you comfortable. I wouldn't want to deprive you of that.

The cursor, though, not so sure about that. I could easily suppress the cursor.


So. The demo is back up and running, and the thing I was running into back in July when I last checked stuff in (I don't remember this stuff, but GitHub does) was that I wanted to have a solid story about what I was doing with arrays of complex objects (like structs, say, like you might need to have for a bunch of asteroids floating across your screen). Would arrays have to be statically allocated? What's initialization like? Am I going to have pointers to these things? Python and Java don't have pointers, except that they do, but you don't see them. Is that what I want?

I want to avoid copying complex objects except by explicit deliberate action. It feels like there are a few other choices that can come as a result of that, but I haven't really meditated deeply enough to make it obvious how things ought to work. Perhaps the next step is to try some stuff, and be prepared to roll back if I don't like how things are working.