YALL (Yet Another LoadLib <g>)

["J. Perkins" <jason@...>]

I have created a new "base" build of my game engine that includes 
only the bootstrapper, scripting services, and a couple of support 
libraries. It was an interesting exercise, I think the code as a 
whole is much cleaner now as a result. What it all amounts to is a 
performance-oriented Lua distro with a formalized extension system. 
In order to compare apples to apples, so to speak, I created a 
minimal wrapper for SDL to run Thatcher's "Meteor Shower" game 
(another interesting exercise, see below).

Before I ramble on too much, you can get it all here:
http://www.379.com/f4/snapshots.html

With this disclaimer: this was a quick refactoring of development 
code. Lots of stuff is missing, but what's there should work.

My engine architecture is component based (a la COM, Unreal, etc.) 
and the extension system reflects that. If you look at the previous 
version of the engine you can get an idea of where I'm heading with 
it. Writing the SDL wrapper was a little clumsy but I think it would 
be possible to adapt toLua or swig to write the code, something I 
might look into. Until I saw Thatcher's game I didn't realize how 
useful a vanilla SDL/OpenGL binding could be for prototyping stuff.

One thing to note is that the extension system is independent of the 
scripting language. By replacing script.dll, I could script with 
Python instead of Lua, without having to rebuild anything else (but 
why anyone would actually *do* that is beyond me ;)  )

In order to mitigate the heap-intensive nature of scripting I put 
together a new memory manager that pools same-sized allocations 
together. On my development machine (700MHz) the game was locked to 
(refresh rate/2) so I wasn't able to measure any improvement. On my 
wife's 450MHz, Thatcher's original version ran at 19fps, while the 
F4 version got 24fps.

The bootstrapper includes the start of an interactive console, but 
it's not operational yet (commented out in main() for now).

Getting Thatcher's code to run was really a pain. I ended up having 
to cut-and-paste a couple of lines at a time in order to be able to 
pin down missing functions and incompatibilities. A line like:

  if (event.type == SDL_QUIT) then

turns into 'if (nil==nil)' when neither object has been defined. 
There were a lot of similar issues, and without an interactive 
debugger the easiest way to track it down was reduce the code. I'd 
hate to have to do this for a larger project! I think I'm going to 
add hooks into the scripting service to allow it to talk to a 
debugger, maybe I can create a plugin for Scintilla or somesuch.

Okay, enough from me for now. Obviously I can go on and on about 
this stuff.

Jason