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#ifndef MONO_CHANNEL_GLSLLIB
#define MONO_CHANNEL_GLSLLIB

#ifdef QSSG_DEFINE_API
#define mono_alpha 0
#define mono_average 1
#define mono_luminance 2
#define mono_maximum 3
#endif

float monoChannel( in vec4 t, const in int monoSource )
{
    if ( monoSource == mono_alpha )
        return( t.w );

    if ( monoSource == mono_average )
        return( ( t.x + t.y + t.z ) / 3.0 );

    if ( monoSource == mono_luminance )
        return( luminance( t.xyz ) );

    if ( monoSource == mono_maximum )
        return( max( t.x, max( t.y, t.z ) ) );

    return( 1.0 );
}

#endif
