http://bugs.winehq.org/show_bug.cgi?id=33265
--- Comment #2 from Ken Thomases ken@codeweavers.com 2013-03-23 18:15:48 CDT --- (In reply to comment #0)
Created attachment 43997 [details] tail of ddraw,display,d3d,wgl log
Not sure what the most proper fix is so I'm going to leave this as a bug report. Basically HoMM 3 (from gog.com) won't start with the mac driver, due to create_context in dlls/winemac.drv/opengl.c failing. It's trying to create a context with color bits set to 64 and alpha bits set to 16, which obviously fails.
Simply commenting out kCGLPFAColorSize, kCGLPFAAlphaSize and kCGLPFADepthSize will let the game start with no obvious drawbacks, but I don't know if it's a proper fix.
Also tried commenting out kCGLPFAMinimumPolicy, that would let the game start, but with a white screen only.
The problem seems to be that D3D is picking that format:
trace:d3d:context_choose_pixel_format Found iPixelFormat=29 for ColorFormat=WINED3DFMT_B5G6R5_UNORM, DepthStencilFormat=WINED3DFMT_D24_UNORM_S8_UINT
The most likely problem is that the Mac driver has listed the formats in the wrong order or reported the wrong format attributes to D3D when queried. It's also possible that D3D has broken logic for picking a format. I'm afraid I'll need to see part of the log that you've omitted, where the Mac driver enumerates the pixel formats and where opengl32/d3d queries them.