Jesse Anders 2011-03-05 23:30:09 PST
It seems that in Windows XP, setting SDL_GL_ACCELERATED_VISUAL to 1 actually
disables hardware acceleration and puts OpenGL in software mode.
In the source code, the corresponding WGL attribute is first set here:
*iAttr++ = WGL_ACCELERATION_ARB;
*iAttr++ = WGL_FULL_ACCELERATION_ARB;
Later, this code:
if (_this->gl_config.accelerated >= 0) {
*iAttr++ = WGL_ACCELERATION_ARB;
*iAttr++ =
(_this->gl_config.accelerated ? WGL_GENERIC_ACCELERATION_ARB :
WGL_NO_ACCELERATION_ARB);
}
Sets it again if SDL_GL_ACCELERATED_VISUAL has a value other than the default.
More importantly, the documentation I found states that
WGL_GENERIC_ACCELERATION_ARB asks for an MDC driver, which, although I don't
know much about this topic, doesn't seem like the correct choice here. As
mentioned previously, the end effect is that requesting hardware acceleration
in Windows XP actually forces the renderer into software mode (on my system at
least), which I'm guessing isn't the desired behavior.
The bitmap ordering is defined such that the numbering refers to the pixel index from left to right, and the number position refers to the bit position in the byte.
SDL_BITMAPORDER_4321 is the fourth pixel at the high bit and the first pixel at the low bit (LSBFirst)
SDL_BITMAPORDER_1234 is the first pixel at the high bit and the fourth pixel at the low bit (MSBFirst)
Frank Zago to SDL
For those interested, here's a snapshot of the current port. I did away with
most of the previous attempt which was based of the sprite engine, because the
support is limited to 128 64x64 sprites. Instead I'm using the gl engine.
The drawback is that either the frame buffer or the gl engine can be used
because there's not that much video memory on a DS.
With minimal changes to their code, it can now run the following tests: ,
testspriteminimal, testscale and testsprite2. The last 2 only run under the
emulator for some reason. The tests are not included in this patch for size
reason.
In 16 bits mode, the 16th bit indicated transparency/opacity. If 0, the color
is not displayed. So I had to patch a few core file to set that bit to 1. See
patch for src/video/SDL_RLEaccel.c and src/video/SDL_blit.h. Is that ok, or is
there a better way ?
The nds also doesn't support windowed mode, so I force the fullscreen in
src/video/SDL_video.c. Is that ok, or is there a better way ?
To get a smaller library, I also tried to not compile the software renderer
when the hardware renderer is compiled in, and define SDL_NO_COMPAT; however
the compilation eventually fails in SDL_surface.c because SDL_SRCCOLORKEY is
defined in SDL_compat.h. Is SDL_NO_COMPAT only for application and not SDL
itself ?
