Figure 1: An animated dancer made of fluid using our position-based fluid control method. AbstractWe present a novel fluid control method that is capable of driving particle-based fluid simulation to match a rapidly changing target while keeping natural fluid-like motion. To achieve the desired behavior, we first generate control particles by sampling the target shape and then apply a non-linear constraint to each control particle, with its neighboring fluid particles keeping a constant fluid density within its influence region. This density constraint is highly in line with the incompressible nature of the fluid, which can drive the fluid to match the target shape in a natural way. In addition, to match a fast moving or deforming target, we add an adaptive spring for each fluid particle in the control region, connecting with its nearest control particle. The spring constraint takes effect only when the fluid particle is far from its corresponding control particle to avoid introducing artificial viscosity. Therefore, the fluid particles are well controlled even if the target shape changes rapidly. Furthermore, we integrate a velocity constraint to adjust the stiffness of the controlled fluid. All these three constraints are solved under position-based framework which enables our simulation fast, robust and well-suitable for interactive applications. We demonstrate the efficiency and effectiveness of our method in various scenarios in real time.

Real time simulation is a challenging subject in crowd simulation. Many approaches have been proposed to simulate the crowd behavior. However, few of them[1] focused on solving collision avoidance problem. In this paper, we present a novel real-time collision avoidance method for crowd simulation, which combines advantages of both continuum-based methods and agent-based methods. Also, by integrating the theory of flock, we improve the result of our simulation to be more realistic.