1. Draw Non Selected objects in the depth buffer
2. Make non selected objects invisible, and draw only the selected objects, by comparing the depth buffer of non selected objects. Write a mask here for visible and hidden edges.
3. Downsample the Mask buffer to half
4. Edge detect the half res buffer, with different colors to hidden and visible edges.
5. Blur the edges of half res/quarter res buffer(quarter res is used for edge glow)
6. Add the blurred edges on top of original scene using the full res mask buffer