It sounds like your fence is made of 4 triangles, unless the two sides are separate surfaces Blitz will mess up the normals.
I suggest modelling just one side of the fence with two triangles and use EntityFX fence,16 to make it double sided.
If this doesn't make sense can you detail how you are creating the mesh, in a modelling program or using CreateSurface?
I suggest modelling just one side of the fence with two triangles and use EntityFX fence,16 to make it double sided.
If this doesn't make sense can you detail how you are creating the mesh, in a modelling program or using CreateSurface?