1. A method, comprising: initializing, by a computer, two or more sweep paths for an input three-dimensional (3-D) model, wherein each of the two or more sweep paths has an associated two or more deformation parameters for applying deformations to the respective sweep path; and iteratively performing, by the computer: obtaining input modifying a value of one of the deformation parameters for one of the two or more sweep paths; and deforming the 3-D model according to the modified value of the deformation parameter for the sweep path.