source: code/archive/skybox/Media/materials/programs/hdr_tonemap_util.glsl @ 10980

const float MIDDLE_GREY = 0.72;
const float FUDGE = 0.001;
const float L_WHITE = 1.5;

/** Tone mapping function 
@note Only affects rgb, not a
@param inColour The HDR colour
@param lum The scene lumninence 
@returns Tone mapped colour
*/
vec4 toneMap(in vec4 inColour, in float lum)
{
        // From Reinhard et al
        // "Photographic Tone Reproduction for Digital Images"
        
        // Initial luminence scaling (equation 2)
    inColour.rgb *= MIDDLE_GREY / (FUDGE + lum);

        // Control white out (equation 4 nom)
    inColour.rgb *= (1.0 + inColour.rgb / L_WHITE);

        // Final mapping (equation 4 denom)
        inColour.rgb /= (1.0 + inColour.rgb);
        
        return inColour;

}