A method is disclosed for defining surface properties in a virtual world. An object includes vertices defining a surface and surface properties. A number of vertex data layers are provided that permit a user to define several properties, including color, that are then combined according to user-specified vertex layer interactions to produce layer values specifying physical properties of the surface. When user input is received at a specified layer, and an object surface property, such as color, is modified. A physical property of the object is updated by combining properties from multiple vertex layers according to user-specified vertex layer interactions to modify the layer values.