【作者】 吴亚刚；

【导师】 曾亮；

【作者基本信息】 国防科学技术大学 ， 计算机科学与技术， 2009， 硕士

【摘要】 实体破碎特效仿真在计算机图形学研究与虚拟现实应用环节中扮演着重要角色。随着可编程图形硬件的大众化投入使用,在数字游戏、影视动画等领域越来越需要复杂、真实感的诸如软体、粘性体、刚体形变及其破碎相关特效。软体、刚体的仿真本身是图形学界一个复杂的研究内容,目前在研究工作中存在的关键问题是学者们过于追求仿真视觉可信性,实时性难以解决。本文在系统研究分析软体、刚体仿真成熟方法的基础上,针对破碎特效的需要,对基于质点弹簧系统和闭合气体压力模型的软体仿真、基于虚节点算法的软体多局部破碎特效进行了研究,对基于破碎模式、局部破碎、Voronoi破碎特征的相关破碎特效进行了研究,完成了相关算法与系统平台的实现。本文主要工作及取得的主要研究成果包括:1)利用虚节点在仿真过程中改变网格拓扑结构的特性,提出基于虚节点的软体多局部破碎特效描述算法,并结合现有基于质点弹簧系统与闭合气体压力模型相结合的软体仿真成熟方法,实现了实时交互式软体破碎仿真平台。2)设计了一种基于八叉树剖分的几何模型局部区域选择算法,利用八叉树结构对实体模型空间结构进行划分,采取交互式的方法选择实体模型具有空间连续性的局部区域,该区域的快速选择是后续研究刚体局部破碎特效的关键性环节。3)提出一种刚体预破碎模式,将实体划分成内部空间连续、互不相交的几个子区域块,采用线性约束连接各子块和组成实体的块内基本元素。线性约束在仿真过程中进行能量传递,当实体与外界发生碰撞时,采用统一算法检测约束的能量承载情况,当它承载能量超过其阈值则该处约束发生断裂,约束的断裂导致子块分离形成破碎特效,不同程度的碰撞将会导致不同位置的约束断裂,进而形成不同程度的破碎特效。4)设计实现了刚体局部破碎特效仿真方法,将局部区域选择算法抽取的子区域与实体剩余部分通过线性约束相连,子区域内的基本元素也通过线性约束进行连接,然后应用预破碎模式,实现了不同程度的实体破碎特效仿真。5)设计基于破碎模式的刚体破碎特效,利用Voronoi图生成随机区域的特性进行子块划分,相关研究工作正在进行中。更多还原

【Abstract】 Object fracturing effects simulation such as Soft Body and Rigid Body has played an important role in the Computer Graphics research and the Virtual Reality applications. As the GPU commonly used in most fields, complicated and realistic soft body, viscosity body, rigid body deformation as well as their fracture effects are largely needed in digital games, and in video animation. At the mean time, soft body and rigid body fracturing effects simulation has strongly attracted the heart of the researchers, and in fact it is complicated, the key problem is that reserarchers trend to focus on the visual reliability, the real-time feature is not solved.We have analyzed the most popular method of soft body and rigid body simulation by the numbers, focusing on the requirement of the fracture effect, we researched the soft body simulation combined with mass-spring system and the pressure model; we researched the virtual node algorithm based multiple fracture effect on soft body simulation; we researched the fracture pattern, local fracture, Voronoi fracture feature based fracture effect, and finally we designed the exact algorithms and implemented the simulation platform. The contributions and relevant work in this paper are as follows:Firstly, make use of the virtual node algorithm that is used to change mesh topology, we proposed the virtual node based multiple local fracture description algorithms, and later it is applied in the real-time interactive soft body simulation platform which use the popular mass-spring system and pressure model.Secondly, we designed octree partition based local area choosing algorithm on the object’s geometric model, octree is used to structure the object, later we use interactive method to choose the continual local area on the surface, quick choosing local area is the key point of the later local fracturing effect research.Thirdly, we proposed the rigid body pre-fracture pattern, object is separated into several spatial continual and non-intersect sub-blocks, and then line-constraint is used to connect the sub-block and the basic element in it. Line-constraint can transfer energy, when the object collides with the environment, we used a unified algorithm to detect how much energy the line-constraint transfers, when the value exceed the pre-fixed value it will break, and the broken constraint would lead to the separateness of the sub-block, which would form fracture, different degrees of collide will lead to different levels of fracture due to the location of the constraint.Fourthy, we designed the local fracture simulation method, the local area choosing algorithm will extra the exact sub-area, line-constraints are used to connect the sub-area with the leaving area, and the basic element is connected by the constraint too. And later we apply the pre-fracture pattern, int the end we get different levels of fracturing effects.Finally, we designed the fracture pattern based fracture effect, we use the voronoi diagram theory, and it is used to generate random sub-area, this is still in research for the future.更多还原