A 2D layer (Layer) is a simple image map. On a 2D layer one can define blending functions, set visibility and transparency. 2D layers are used for texture layers and screen layers. 2D layers can be serialized from/to plain image files.

A texture layer is an item of a texture set assigned to a surface and can be painted on independently from other layers.

Screen layers are planes attached to the active camera that have a texture assigned and can be painted to.