quipkit

I just spent the last few days trawling through someone else's multi-threaded C++ Linux audio code, so I thought I'd share a few of my experiences.

First: The commit.

That code converts direct audio hardware access via ALSA into newer plugin-based output. It also fixes a race condition that occurs at the seam of the two subsystems involved: the client code provided a mixer callback that used a buffer that is initialised immediately after the server spawns the thread that needs it. It's a mistake made by the code's author, but to be fair I wouldn't have spotted it either if the code hadn't segfaulted on me.

If you ever find yourself in this situation, here are some tips:

• Print statements really work. Yes, even with threads. Especially with C++, where control flow isn't obvious.

• In threaded code, if you just insert print statements and behaviour changes, that's almost certainly a sign of a race condition.

• C++ is harder to grep through than C, but it still works, if less effectively. C++ adds a lot of context that makes individual identifiers less useful on the isolated lines printed by grep.

• Persistence pays. Even if the best programmers in the world say that threaded debugging is difficult, it can still be done.

• If you're in college/university and going the computer/software route, take the Operating Systems course(s). Threads and concurrency get a lot of good exposure in them.

Quipkit is a work-in-progress (read: not even near finished) indie RPG dev kit. This blog entry describes how we might make an RPG using Quipkit.

• 1 Vague Game Description
• 2 Initial Design
  • 2.1. Game States
  • 2.2. Resources
  • 2.3. Tools
• 3 Revising the Design
• 4 Making the RPG (Finally!)
  • 4.1. Programming the Game States
  • 4.2. Organising Resources
    • 4.2.1. Resource Support Code
    • 4.2.2. Making Custom Tools
    • 4.2.3. Make the Resources
  • 4.3. Testing the Game
• 5 Summary: The Finished RPG
• 6 Conclusion

1. Vague Game Description

Most games start as vague ideas, and indie RPGs are no exception. Here's one for our hypothetical RPG:

You play a guy in a traditional fantasy RPG. You walk around a map of grass and water, and every so often you encounter a monster. You exchange blows with said monster in the battle system until either you or it dies. If you win, you gain experience. With enough experience, the guy can gain a level and grow in strength. This continues until the player chooses to exit.

It shall be dubbed... Island Dude.

How would be breathe life into this little RPG? Read on!

I was working on a project when general upgrade instability caused it to stop working on my development machine (read: starting OpenGL kills X for some reason). Off of Arch and onto Ubuntu 9.04, and I find that my Linux-based project won't build under Linux.

Autoconf is a set of tools that smooths over differences in build environments, like different file system conventions, library names, search paths, tool chains, and so on.

The following is based on a series of long articles over at the Free Software Magazine: the only tutorial/guide that didn't attempt to shove 20 years of history down my throat from the get-go. It's my personal reference and I'll update it as I learn.