A computer-implemented method for constructing a design characterized by a double patterning layer is presented. The method includes receiving the design in a memory of the computer when the computer is invoked to construct the design. The method further includes generating, using the computer, a multitude of fill shapes along a multitude of tracks associated with a multitude of net shapes. The multitude of fill shapes and the multitude of net shapes are decomposable into two colors in accordance with a spacing constraint of the double patterning layer.