Don't lose precision while linearizing light grid

In one step of light grid processing, values were converted from sRGB to
linear and stored in bytes. This unnecessarily loses precision during
the calculation.

Author: slipher

src/common/Color.h

@@ -55,6 +55,7 @@ inline void convertFromSRGB( float* v, bool accurate = true )
 	v[ 2 ] = convertFromSRGB( v[ 2 ], accurate );
 }
 
+// Beware: this instantly loses precision, there are less than 256 possible outputs!
 inline void convertFromSRGB( byte* bytes, bool accurate = true )
 {
 	vec3_t v;

src/engine/renderer/tr_bsp.cpp

@@ -3590,9 +3590,6 @@ void R_LoadLightGrid( lump_t *l )
 		tmpDirected[ 2 ] = in->directed[ 2 ];
 		tmpDirected[ 3 ] = 255;
 
-		R_LinearizeLightingColorBytes( tmpAmbient );
-		R_LinearizeLightingColorBytes( tmpDirected );
-
 		R_ColorShiftLightingBytes( tmpAmbient );
 		R_ColorShiftLightingBytes( tmpDirected );
 
@@ -3602,6 +3599,12 @@ void R_LoadLightGrid( lump_t *l )
 			directedColor[ j ] = tmpDirected[ j ] * ( 1.0f / 255.0f );
 		}
 
+		if ( tr.worldLinearizeTexture )
+		{
+			convertFromSRGB( ambientColor );
+			convertFromSRGB( directedColor );
+		}
+
 		const float forceAmbient = r_forceAmbient.Get();
 		if ( ambientColor[0] < forceAmbient &&
 			ambientColor[1] < forceAmbient &&