Real-time Fluid Simulation And Control

With the continuing development of computer graphics,the fluid simulation is more and more popular in movies,advertises and video games.The cool fluid effects not only make the picture alive but also enhance the sense of reality for the virtual scene.However,the current methods to produce fluid special effects are too computation expensive to apply in real-time systems.In this paper,we propose a series of methods to achieve a real-time fluid simulation and control system.First,we implement a real-time particle-based fluid simulation framework.It keeps fluid incompressible by constraining the neighbouring particles density of each fluid particle using a position-based integration method.An adaptive repulsion force is introduced to improve the particle distribution and a vorticity confinement term is used to compensate the damping of numerical simulation.Our method could keep the simulation stable even for large time step and is able to achieve real-time fluid simulation for large scale scene with the parallel computation capability of GPU.Second,we present a fluid control method for particle-based fluid simulation.It first converts the target model to control particles by a voxelization method.The fluid is driven to match the target shape by constraining the neighbouring fluid density of each control particle.To avoid fluid losing control when matching a rapid changing target,we add an adaptive spring for each fluid particle with its nearest control particle.The spring force could pull fluid back to the control area.We also integrate a velocity constraint to adjust the stiffness of the controlled fluid.The control force in our method is in line with the original acting force between fluid particles.So the simulation could keep stable even under a strongcontrol force and the fluid detail will not be disturbed.Finally,we also present a real-time surface rendering method for the fluid particles.The method is based on the ray-casting technique and only the front most surface of fluid is rendered.The empty space is skipped by the depth image of particle splatting.Finally,we produce a high-quality surface rendering result by combining with the Principal Component Analysis(PCA)technique.The computation is focused on the fluid surface on screen space and is irrelevant to the particle number and the scene size.Therefore,it is well suitable for the real-time rendering or fast previewing of the large scale fluid simulation.