Variform Cloth With Different Kinds Of Materials Rendering In Real Time

Cloth simulation and rendering methods which based on the physics are widely used in the field of 3D graphics.But because cloth has some characteristics such as a complex structure and soft texture and so on,the fabric simulation has become a hot and difficult field in computer graphics and virtual reality research.Different cloth materials have different dynamic characteristics,and it is very important to simulate different cloth materials in real time and to realize the movement characteristics of different materials.Firstly,in order to achieve the movement of cloth with different materials,the key is to use the appropriate model to build the cloth structure.In this paper,we build the cloth model using a mass spring model in which the triangles are the carrier.In this model,we consider the fabric as a mesh structure consisting of particles and springs,each of which is connected by a spring.The motion between cloth particles follows the Newton's second law of motion.We use the improved Euler's integral method to solve it numerically,the velocity and position of cloth particles are calculated again between this time and the next time,and the error of the large time step is reduced,at the same time,the stability of the whole system is improved.Secondly,in order to simulate the different forms of cloth,we introduce a Perlin Noise function to construct a variable random wind field,and simulate the movement of the cloth in the wind field at different speeds in real time.When the cloth collides with the rigid bodies,in order to avoid penetrate of the cloth,we need to perform collision detection and collision response to simulate the form of the cloth with different hardness after it collides with rigid bodies.Thirdly,in order to effectively simulate the material of different cloth in real time,we use physics-based illumination model—BRDF model combined with the normal map technology to render the fabric.The BRDF model can easily establish cloth materials which are close to the real materials in a variety of light environments.We mainly calculate the reflectance and scattering of the rays which illuminate to the cloth.The calculation of reflectance is called specular,including the normal distribution term,the shadow-mask term and the Fresnel reflection term and the calculation of scattering is called diffuse.At the same time,by comparing the normal methods of obtaining surface reflection data of different cloth materials,we use the normal map to obtain the normal of the surface of different cloth materials,not only do not need to use expensive equipment and complex methods,but also speed up the material rendering speed,and improve the real-time characteristic of our simulation system.Finally,we use the windows system,combined with C# language and shader rendering on the Unity3 D engine platform,we design and develop the multi-form and real time rendering simulation system of different cloth materials.Experiments show that the method can simulate the multi-morphological effect of cloth with different materials with the mass spring as the fabric model,and the simulation detail and realism are strengthened,and the method also meet the real-time requirement.