Okay, last night I was curious as to why Petit Copter kept crashing the way it does. I initially thought it was DirectSound related, but it turns out that it was really a problem with our implementation of EmuIDirect3DDevice8_SetRenderTarget. The fix was so easy, I wanted to slap myself! After that it went ingame.
After going ingame, it turns out that the game is more complex than I thought in some ways. It turns out that the game does actually use vertex shaders! Although that's not really a problem as Petit Copter's vertex shaders were really simple to convert. When I first got Petit Copter ingame, I noticed that the only thing I could see was the helicopter's rotor. This was because Cxbx compensates for the Xbox's ability to use negative numbers to identify vertex shader constants (c-96 to c96), so Cxbx adds 96 to the vertex shader constant ID of each shader instruction to fix that. This caused bugs in games using XDK 4361 and earlier (so far) and caused 3D not to render. So what I did was add 96 in EmuIDirect3DDevice8_SetVertexShaderConstant and everything that used vertex shaders in XDK 3911 - 4361 worked fine. It's a dirty hack and I'm not sure if it's a good idea to leave it there, but oh well, time will tell.
"So, how well does it run in game?" Well, everything is smooth ingame. No framerate issues as the graphics are really simple. "If everything is smooth, why can't it be considered playable yet?" Good question. There's another bug somewhere, and I can't figure out what it is. So far, it's exclusive to this game. There's a stack corruption problem in this game (might be the generated exe or CxbxKrnl.dll causing it) and it's really hard to track! If I can fix that, then the game will be considered playable. The bug is completely random. Sometimes you'll get a crash immediately, other times it won't show up for about 30 seconds if you're lucky. So if you want, watch the youtube video (link below).
Cxbx WIP: Petit Copter [Part 2] (Ingame)
Hope you enjoy it.
Name that Ware May 2013
2 weeks ago