Graphical Modeling And Rendering Of Fracture

The simulation of the phenomenon of fracture has attracted widespread attention inrecent years. It has important theoretical and practical significance not only in gamedevelopment, but also in other areas, such as the production of movie special effects,materials analysis, military simulation and virtual battlefield environment, etc. As acommon physical phenomenon in everyday life, fracturing effects greatly affect theuser’s experience in virtual reality, computer game and film industry. Thus, thefracturing simulation has become a new hotspot in computer graphics in recent years.This dissertation has done deep research on graphical modeling and renderingtechnology of fracture.The main research achievements are detailed as follows:(1) Fracturing rigid body has been one of the hotspots and the difficulties in thefield of computer graphics in recent years. The common used finite element analysisalways needs complex physical calculations, which cannot meet the real-timerequirements of game and simulation. In this dissertation, a novel Voronoi diagrambased fracturing rigid body simulation approach is proposed, which gets a result withstrong physical reality in real time, by using the pre-fracture technology. Firstly, withthe analysis of fracturing progress of brittle rigid body, the seed points which fit well ofthe normal distribution are obtained, and the Voronoi polygons are generated throughthe off-line incremental algorithm and Graham Convex Hull algorithm. Secondly,according to the energy conservation equation and mechanical analysis, the radius of thefracture area and the crack area are ascertained, and in accordance with the restriction ofcollision energy conversion, the velocities of fragments are derived. Lastly, the collisiondetection has been realized and the velocity, attitude, etc. of the fragments are calculated.Experimental results show that this method can meet the real-time requirements ofgames and the interactive simulation, while the generation and movement of fragmentsconsistent with the true physical laws, and have a strong sense of reality.(2) In this dissertation, a particle-based framework is presented to simulate thefracture phenomenon in computer graphics field. First, the object is represented asdiscrete particles, and then we introduce the Extend Discrete Element Method (EDEM)simulation to describe the interactions between neighbouring particles based on thematerial mechanics analysis. To process the fracture, a reverse idea to traditionalmethod is used to cooperate with auxiliary cone algorithm, which called anti-fracturemechanism. The physical computation is executed on the GPU with CUDA and auniform grid data structure is used in order to search the neighbouring elementseffectively. Experiment results demonstrate the feasibility and effectiveness of ourmethod. (3) We introduce a novel method to simulate the fracture of heterogeneousmaterials and implement it efficiently on GPU with CUDA. First, the object isrepresented as discrete particles, named movable cellular automata, and then theMovable Cellular Automata method (MCA) is used to simulate the material andphysical properties as well as to determine when the fracture occurs. The simulation andrendering all run on GPU and the vertex buffer object (VBO) is used to avoid the costlycommunication between CPU and GPU. We demonstrate the feasibility andeffectiveness of the proposed method by the experimental results.(4) The traditonal meshless method is difficult to address the singularity problemof the stress field of the crack tips. This dissertation presents an efficient approach tosimulate the deformation and fracture based on the local radial point interpolationmethod (LRPIM). When the shape function is constructed, a singular term is added forthe expansion of the radial basis function. Combining the LRPIM and the fracturecriterion based on the damage mechnism, the simulation process of deformation andfracture has been implemented. And the simulation results are rendered by the splattingtechnology based on point. The experimental results show that, compared to theconventional meshless method, our method can solve the singularity problem of thecrack tips, and the efficiency of rendering has been improved profiting from thesplatting technology.