In this paper we address interactive shape modelling of geometric shapes defined by mathematical functions. We introduce mathematical operators that implement modifications of geometry and appearance of the shapes. Any of the operators involved in creating the shape can be edited, modified or removed at any time, thus allowing for a great flexibility of the modelling pipeline and opening prospects for efficient reusing and improving of the previously created models. Interactive modification of the function model with concurrent visualisation of the respective polygonal mesh lets us provide both the interactivity and any required level of detail resulting in photo-realistic appearance of the shapes. r 2006 Elsevier Ltd. All rights reserved.