Hybrid Subdivision Algorithm with Special Effect

Previous methods for generation of sharp features of subdivision surfaces were based on that initial control meshes are either triangle-only meshes or quadrangle-only meshes.However,in engineering surface modeling,general shapes designers often want to model certain regions with triangle and quadrangle hybrid patches structure.In order to overcome the defect in generation of sharp features utilizing traditional approaches,in this paper,we propose a method for creating sharp features and sem-i sharp features on hybrid subdivision surfaces.By local modifying hybrid subdivision rules,sharp features such as dart,cusp, crease and corner are generated.We also give eigenanalysis of local subdivision matrices for the piecewise smooth subdivision rules that include sharp features,and the convergence and smoothness of the limit surface are discussed.Meanwhile,by controlling sharpness using discrete curvature at feature vertex,we realize sem-i sharp features effect.Examples demonstrate explicit and efficiency of our method.