class RenderableFace implements IRenderable {
 List<RenderableVertex> vertices;

 Vector3 centroidWorld, centroidScreen, normalWorld;

 List vertexNormalsWorld, uvs;

 Material material;
 Material faceMaterial;

 num z;

 RenderableFace(int size) :
   centroidWorld = new Vector3.zero(),
   centroidScreen = new Vector3.zero(),

   normalWorld = new Vector3.zero(),
   vertexNormalsWorld = [ new Vector3.zero(), new Vector3.zero(), new Vector3.zero(), new Vector3.zero() ],

   material = null,
   uvs = [[]],

   z = null {
   vertices = new List.generate(size, (_) => new RenderableVertex(), growable: false);
 }
}