uniform half4 _Color;

half4 main() : COLOR0
{
    const half c1 = max(_Color.r, _Color.g);
    const half c2 = _Color.b * _Color.a;

	// This is GLSL 1.20
    // ...which means this one can stay const
    // since it only calls built-in function
    const float c3 = log2(4 * 4);

    const float c4 = -_Color.r;
    return half4(c1, c2, c3, c4);
}