SpeedX preview effect

Hi guys,

http://www.youtube.com/watch?v=T8py5rEwyic

I want to implement in my game an effect of obstacle preview like this. As you can see when an obastacle is placed in one column it "paints" the column from the obstacle to the player. I come up with two solutions but none of them is "great"

• First solution: I can store the coordinates of the obstable on the "grid" and say "from here paint it red". But this means I have to cycle trought every face of the grid and the mesh must have separate meshes for every face.
• Secondo solution: UV offset a texture. But I don't know if can be achieved with multiple obstacle on the same columun or column adiacents.

Any tips or idea?