Document new OpenGL feature
authorPatrice Mandin <patmandin@gmail.com>
Mon, 06 Dec 2004 15:01:00 +0000
changeset 1007335d9376a2cd
parent 1006 3d9a199d2a70
child 1008 5fb02068b648
Document new OpenGL feature
README.MiNT
     1.1 --- a/README.MiNT	Mon Dec 06 04:17:56 2004 +0000
     1.2 +++ b/README.MiNT	Mon Dec 06 15:01:00 2004 +0000
     1.3 @@ -75,6 +75,9 @@
     1.4  	Set to 'xbios' to force xbios video driver
     1.5  	Set to 'gem' to force gem video driver
     1.6  
     1.7 +SDL_VIDEO_GL_DRIVER:
     1.8 +	Set to filename to load as OpenGL library, if you use SDL_GL_LoadLibrary()
     1.9 +
    1.10  SDL_AUDIODRIVER:
    1.11  	Set to 'mint_gsxb' to force Atari GSXB audio driver
    1.12  	Set to 'mint_mcsn' to force Atari MCSN audio driver
    1.13 @@ -126,6 +129,21 @@
    1.14  ==============================================================================
    1.15  VI.  More informations about drivers:
    1.16  
    1.17 +OpenGL:
    1.18 +	The default is to use the Mesa offscreen driver (osmesa.ldg). If you want
    1.19 +	to use an older OpenGL implementation, like mesa_gl.ldg or tiny_gl.ldg,
    1.20 +	your program must use SDL_GL_LoadLibrary() to do so, and retrieve the
    1.21 +	needed function pointers with SDL_LoadFunction(). In all cases, the OpenGL
    1.22 +	context is taken care of by SDL itself, you just have to use gl* functions.
    1.23 +
    1.24 +	However, there is one OpenGL call that has a different prototype in the old
    1.25 +	implementations: glOrtho(). In the old implementations, it has 6 float as
    1.26 +	parameters, in the standard one, it has 6 double parameters. If you want
    1.27 +	to compile testdyngl, or any other SDL program that loads its OpenGL
    1.28 +	library, you must change the glOrtho() prototype used in this program. In
    1.29 +	osmesa.ldg, you can retrieve a glOrtho() with double parameters, by searching
    1.30 +	for the function "glOrtho6d".
    1.31 +
    1.32  Xbios video:
    1.33  	Video chip is detected using the _VDO cookie.
    1.34  	Screen enhancers are not supported, but could be if you know how to