Interactive modeling and subdivision of flexible equilateral triangular mechanisms

Based on the requests from architects, we developed a system which allows to interactively design and subdivide flexible triangular surfaces. Due to economical reasons the number of different types of building elements should be small. For that reason we only use equilateral base triangles of unique size with the possibility of subdivision. To allow to interactively move vertices and to ensure constant edge length we use force-directed methods instead of inverse kinematics. This paper describes the data structure, the algorithm and the influence of subdivision on the kinematic flexibility of the mesh.