    # File lib/rubygame/color/models/base.rb, line 55
            def over(other)
                    c1, c2 = self.to_rgba_ary, other.to_rgba_ary
                    a1, a2 = c1[3], c2[3]

                    rgba = [0,1,2].collect do |i|
                            clamp( a1*c1.at(i) + a2*c2.at(i)*(1-a1) )
                    end

                    rgba << ( a1 + a2*(1-a1) )

                    wrap( rgba )
            end