What the command is doing, is pointing the normals in the opposite direction. The normals of the vertices, are uses to calculate, how the lights affect the polygons. by flipping the mesh, or negative scaling the mesh, you are, flipping also the normals.
If you can, it wouldn't be hard to invert/mirror the mesh, using code. Find the centre point. IE. if you want to mirror it along the X Z plane, then uses the Y centre point. Then loop through all the verts, and alter their positions accordingly.
If you can, it wouldn't be hard to invert/mirror the mesh, using code. Find the centre point. IE. if you want to mirror it along the X Z plane, then uses the Y centre point. Then loop through all the verts, and alter their positions accordingly.