As focus in modern computer games shifts from purely realistic rendering to a more realistic environment for the user, interactive physical simulation of a broad range of objects - demanding a believable appearance, rather than physical correctness - becomes increasingly important. Traditionally physically based simulation is done on the CPU, however the pace of innovation in graphics hardware is staggering and continues to outpace processor development. In addition, the programmable rendering pipeline makes graphics hardware capable of doing much more than simply rendering a scene. This book combines both aspects by presenting an approach of performing physically based modelling solely on graphics hardware by using the concept of Memory Objects. The algorithms presented in this work allow for the simulation of cloth, rigid and soft bodies. The main aspects of physically based modelling discussed in this book are: verlet integration, containing shape, collision detection and collision response.