mirror of
https://github.com/FWGS/xash3d-fwgs
synced 2024-12-11 11:30:08 +01:00
88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
/*
|
|
gamma.c - gamma routines
|
|
Copyright (C) 2011 Uncle Mike
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
*/
|
|
|
|
#include "common.h"
|
|
#include <mathlib.h>
|
|
#include "gl_local.h"
|
|
|
|
//-----------------------------------------------------------------------------
|
|
// Gamma conversion support
|
|
//-----------------------------------------------------------------------------
|
|
static byte texgammatable[256]; // palette is sent through this to convert to screen gamma
|
|
static byte lightgammatable[256];
|
|
static int lineargammatable[1024];
|
|
static int screengammatable[1024];
|
|
|
|
void BuildGammaTable( float lightgamma, float brightness )
|
|
{
|
|
int i, inf;
|
|
float f, g, g1, g3;
|
|
|
|
lightgamma = bound( 1.8f, lightgamma, 3.0f );
|
|
brightness = bound( 0.0f, brightness, 10.0f );
|
|
|
|
if( brightness <= 0.0f )
|
|
g3 = 0.125f;
|
|
else if( brightness > 1.0f )
|
|
g3 = 0.05f;
|
|
else g3 = 0.125f - (brightness * brightness) * 0.075f;
|
|
|
|
g = 1.0f / lightgamma;
|
|
g1 = GAMMA * g;
|
|
|
|
for( i = 0; i < 256; i++ )
|
|
{
|
|
f = pow( i / 255.f, GAMMA );
|
|
|
|
// scale up
|
|
if( brightness > 1.0f )
|
|
f = f * brightness;
|
|
|
|
// shift up
|
|
if( f <= g3 ) f = (f / g3) * 0.125f;
|
|
else f = 0.125f + ((f - g3) / (1.0f - g3)) * 0.875f;
|
|
|
|
// convert linear space to desired gamma space
|
|
inf = (int)( 255.0 * pow( f, g ));
|
|
|
|
lightgammatable[i] = bound( 0, inf, 255 );
|
|
}
|
|
|
|
for( i = 0; i < 256; i++ )
|
|
{
|
|
f = 255.0 * pow(( float )i / 255.0f, TEXGAMMA );
|
|
inf = (int)(f + 0.5f);
|
|
texgammatable[i] = bound( 0, inf, 255 );
|
|
}
|
|
|
|
for( i = 0; i < 1024; i++ )
|
|
{
|
|
// convert from screen gamma space to linear space
|
|
lineargammatable[i] = 1023 * pow( i / 1023.0, g1 );
|
|
|
|
// convert from linear gamma space to screen space
|
|
screengammatable[i] = 1023 * pow( i / 1023.0, 1.0 / g1 );
|
|
}
|
|
}
|
|
|
|
byte LightToTexGamma( byte b )
|
|
{
|
|
return lightgammatable[b];
|
|
}
|
|
|
|
byte TextureToGamma( byte b )
|
|
{
|
|
return texgammatable[b];
|
|
} |