If you're using Max and the Edit Normals modifier, then all you have to do is select all the normals (Ctrl+A) and press the Reset button in the modifier.
Hi there! I'm currently trying to get a huge number of grass planes to shade properly. Basically, I edited the normals of the original patch of grass so that all vertices normals would face up. It shaded good so I decided to paint that mesh on my ground mesh with the 3ds Max paint object tool. My problem is that the mesh…