Real-time Simulation Of Large-scale Deep Ocean Foambased On OSG Ocean

Simulation of large-scale deep sea has been one of the most challenging problems in the field of computer graphics in nature. With the development of computer hardware technology, ocean simulation constantly used in military exercises, 3D games, movie special effects, advertising and other industries. Compared with other natural features, fluctuation of the sea is very complex, and therefore how to show the movement of the sea more realistically, has become the focus of research of many experts and scholars. In this paper, based on the simulation of current large-scale deep-sea foam, the research aims at the problem of reality and poor real-time performance. The details are as follows.Firstly, construct a dynamic model of the waves, use Phillips spectrum to obtain frequency domain amplitude values of waves, then calculate the sea surface mesh vertex values with time-varying through Inverse Fast Fourier Transform(IFFT), thereby converting the frequency domain amplitude values obtained to spatial domain height value, optimize the fourier coefficients to generate sea surface height field. Then superimpose the displacement in the horizontal plane to form choppy waves.Secondly, adopt seamless adaptive Levels of Detail(LOD) mesh to generate the sea and stitching them, which achieving simulation of the unlimited ocean; For complex ocean lighting scenes, add the sky-box textures under different climatic conditions and arbitrary switching; Utilizing Snell’s law simulate light scenario over the sea, and improving Fresnel reflection coefficient until the refracted light and reflected light under the sea closer to the real light; Introducing Blinn-Phong lighting model for illumination rendering the sea surface under the mapping of sky background; After that we join the ships, islands and other 3D models and the rain, snow scenes particle system.Thirdly, using small patch tile structure although can reduce the amount of calculation of the deep ocean surface,however, this method leads to the ocean surface foam obvious repetitive at position, seriously affected the results of the simulation fidelity and realism. To solve this problem, we design a dynamic threshold condition for determining whether a pixel is displayed on the sea foam to reduce foams repetitive at position. As for the sea foam repetitive because of the cyclical movement of the waves, we propose to set up a texture paste gallery, and the introduction of random function which can randomly selected textures; then with the help of a smooth Hermitian difference simulation of the foam light intensity, so as to make the foam in the sun of the simulation more real.Finally, using OSG open source senior graphics library, the Open GL Shading Language(GLSL) to design and realize the emulation system of deep-sea waves and foams.Experiments show that this method not only can eliminate the wave foam position repeatability, but also can eliminate the wave cycle repeatability of foams, improving authenticity in the ocean simulation.