Backface

Keywords: Backface culling, Doublesided

The backface of a polygon is the one facing away from the normal. By default, most engines will not render this (backface culling) to make it faster. However, it's usually possible to override this with a flag that tells the mesh to render double sided. This can be useful for thin effects that are rendering on a quad that you can see from any angle.

Sometimes it's preferable to simply duplicate the mesh in your DCC and flip the normals on the duplicate. This achieves the same thing for approximately the same cost, but it gives you a bit more control, should you want to alter the look based on which side you are looking at.