[Adonthell-devel] Bug in SDL gfx backend module (?)

[Kai Sterker]

While adding some visual debugging aids to the collision system, I
stumbled across what appears to be a bug in the SDL graphics code. I
didn't want to spend much time tracking it down, so I wrote a simple
test to reproduce it (and work around it in my own code).

The test program can be found at
http://cvs.savannah.nongnu.org/viewvc/adonthell/test/imagetest.cc?root=adonthell&view=markup

What happens is that the main loop runs once, than triggers the crash
during the second iteration:

Thread 0 Crashed:
0   _sdl.so                     0x04de9d40
gfx::surface_sdl::put_pix(unsigned short, unsigned short, unsigned) +
192 (surface_sdl.cc:167)
1   libadonthell_gfx.0.dylib    0x004ad800
gfx::surface::draw_line(short, short, short, short, unsigned,
gfx::drawing_area const*) + 560 (surface.cc:172)
2   imagetest                   0x00003d58 image_test::main() + 344
(imagetest.cc:50)
3   _sdl.so                     0x002d3b80 -[SDLMain
applicationDidFinishLaunching:] + 76
[...]
21  _sdl.so                     0x002d3ae8
CustomApplicationMain(adonthell::app*) + 604
22  _sdl.so                     0x002d3bc0 main_init + 32
23  libadonthell_main.0.dylib   0x002693bc adonthell::app::init() +
1036 (adonthell.cc:237)
24  libadonthell_main.0.dylib   0x00269428 main + 72 (main.cc:81)
25  imagetest                   0x0000217c _start + 760
26  imagetest                   0x00001e80 start + 48

Since I'd rather invest my time into the collision stuff, I'd like to
leave this one to somebody else to figure out. That's possibly a nice
exercise for somebody to get a little more familiar with the code base
:-).

Kai