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One fo the frustrations for a lot of users of Quake is the lack of gamma adjustment, meaning they have to adjust their monitor everytime they want to play Quake (and yes I know some cards have OpenGL settings seperate to desktop, but not all) I remembered an old bit of code of LordHavoc's that placed a blended white quad over the screen, giving more of a contrast change than a gamma change, but the idea was solid. So I sat down and hacked around with it for a while, and got a working gamma adjuster! This has only been tested on Geforce and TNT2 cards so far, so may not work for everyone In GL_RMAIN.C, at the top, just after the other variable definitions paste in this:
extern cvar_t v_gamma; // muff
// idea originally nicked from LordHavoc
// re-worked + extended - muff 5 Feb 2001
// called inside polyblend
void DoGamma()
{
if (v_gamma.value < 0.2)
v_gamma.value = 0.2;
if (v_gamma.value >= 1)
{
v_gamma.value = 1;
return;
}
//believe it or not this actually does brighten the picture!!
glBlendFunc ( GL_DST_COLOR, GL_ONE_MINUS_SRC_ALPHA);
glColor4f (1, 1, 1, v_gamma.value);
glBegin (GL_QUADS);
glVertex3f (10, 100, 100);
glVertex3f (10, -100, 100);
glVertex3f (10, -100, -100);
glVertex3f (10, 100, -100);
//if we do this twice, we double the brightening effect for a wider range of gamma's
glVertex3f (11, 100, 100);
glVertex3f (11, -100, 100);
glVertex3f (11, -100, -100);
glVertex3f (11, 100, -100);
glEnd ();
}
//some code from LordHavoc early DP version
void R_PolyBlend (void)
{
if (!gl_polyblend.value)
return;
GL_DisableMultitexture();
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable (GL_BLEND);
glDisable (GL_DEPTH_TEST);
glDisable (GL_TEXTURE_2D);
glLoadIdentity ();
glRotatef (-90, 1, 0, 0); // put Z going up
glRotatef (90, 0, 0, 1); // put Z going up
if (v_blend[3])
{
glColor4fv (v_blend);
glBegin (GL_QUADS);
glVertex3f (10, 100, 100);
glVertex3f (10, -100, 100);
glVertex3f (10, -100, -100);
glVertex3f (10, 100, -100);
glEnd ();
}
//gamma trick based on LordHavoc - muff
if (v_gamma.value != 1)
DoGamma();
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDisable (GL_BLEND); // muff
glEnable (GL_TEXTURE_2D);
glEnable (GL_ALPHA_TEST); //muff
}
You should now have a working gamma adjuster. Enjoy, muff |
