Collision handling

To improve the realism of our simulation, we include cloth-object collisions. The collision preocessing is performed in two steps. The first step is the collision detection, and the second is the collision response.

  • Collision detection

    Our simulation includes fast collision detections with primitive objects : sphere, plane, cylinder. These three types of object are interesting : firstly, collision with these objects are easy to detect and can be used to approximate more complex objects. For more details on mathematic equations, see report on papers section. However, we wanted to manage directly collisions between imported 3D objects and the cloth, so we implemented a collision detection algorithm based on the well-kown octree method. For more details on this algorithm, see report on "papers" section.

  • Collision response

    We use a very simple collision response mechanism. When a node collide an object, we first move its position back to the surface of the object and then cancel the normal velocity. This simple mechanism is well adapted to cloth and gives good visual results. The other advantage of using this collision response is that it does not introduce some instability in the system. Collision response is separated from the integration step.

Notice that we also worked on cloth-cloth collision but it was too expensive to be used in a real-time simulation.

All rights reseverd to Roque Marie, Parle Thomas, Reboul Alexandre, Tornieri Christophe