Research Of Flame Render In Physical Method

Simulation of natural phenomena has been a hot research in computer graphics. The main study is to use a computer to simulate real-world objects and natural phenomena. For example, fire, waves, clouds and other natural phenomena simulation, this can significantly improve the level of graphic realism of the scene. Among them, the real-time rendering of realistic flickering flame with wind is a sure fascinated thing, fire have a wide application and further development needs in film and television production, disaster simulation, animation, entertainment and other fields.The usual method which simulates the irregular features such as the flame is to use particles system and dynamic texture, but both approaches have their limitations. With the rapid development of computing power and graphics processor parallel computing power increased, it make physics-based approach come true for the flame simulation, the physical method obtain more realistic flame than the method of texture and particles. Many previous researchers have made a number of physics-based simulation methods for the flame, but they all are based on the incompressible Navier-Stokes equations. This article uses the compressible Navier-Stokes equations to simulate the flame shape. The compressible equation less solving a set of physical quantities than can not be compressed equation, so reduce the complexity of the algorithm.This article solves the Navier-Stokes equations by calculating the external force term (density term), diffusion, advection term and the mass conservation. Then, fix the flame RGB value and alpha channel by density field which obtained by solving the Navier-Stokes equations and flame pattern, ultimately, achieve the simulation of flame. Enable flame interactive by controlling the Navier-Stokes equation with external force term. This article also simulate the external obstacles by setting some additional boundary conditions, make flame response to obstacles blocking of outside world.Navier-Stokes equations is the most time-consuming aspect of flame simulation process, We use the cuda for GPU general computing, transfer the part of the Navier-Stokes equation solving algorithm which can be parallel to the GPU, reducing the burden on CPU, improving the efficiency of the algorithm. In this paper, we give the tow algorithms, simply solving the NS equations on CPU, and the CPU and GPU cooperation to solve the NS equation. The efficiency of the latter than the former has some improvement. Finally, analysis the two most influential factors for the flame simulation algorithm, and give a quantitative performance analysis of data.