1. A method, comprising: applying, by one or more computing devices, a deformation to a three-dimensional (3-D) model in response to user input, said applying the deformation to the 3-D model comprising: receiving user input specifying a curve to be applied to a displayed representation of the 3-D model for deforming the 3D model; displaying the curve at least partially on the displayed representation of the 3-D model; deforming the curve in response to user input manipulating a selected point on the displayed curve; and deforming at least a portion of the 3-D model according to the deformation of the curve.