Nonconvex Rigid Bodies with Stacking

Eran Guendelman

Stanford University

Robert Bridson

Stanford University

Ronald Fedkiw

Stanford University




We consider the simulation of nonconvex rigid bodies focusing on interactions such as collision, contact, friction (kinetic, static, rolling and spinning) and stacking. We advocate representing the geometry with both a triangulated surface and a signed distance function defined on a grid, and this dual representation is shown to have many advantages. We propose a novel approach to time integration merging it with the collision and contact processing algorithms in a fashion that obviates the need for ad hoc threshold velocities, and show that this approach matches the theoretical solution for blocks sliding and stopping on inclined planes with friction. We also present a new shock propagation algorithm that allows for efficient use of the propagation (as opposed to the simultaneous) method for treating contact. These new techniques are demonstrated on a variety of problems ranging from simple test cases to stacking problems with as many as 1000 nonconvex rigid bodies with friction as shown in figure 1.

Figure 1: 1000 nonconvex rings (with friction) settling after being dropped onto a set of 25 poles. Each ring is made up of 320 triangles, and each pole is made up of 880 triangles.
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SIGGRAPH Slides [ppt]

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