ABSTRACT This paper introduces an object oriented approach to the boundary element method (BEM) a... more ABSTRACT This paper introduces an object oriented approach to the boundary element method (BEM) applied to solid elastostatic analysis. The proposed solution is made up of object classes which can be used for implementing object oriented programs of numerical analysis based on BEM. Furthermore, one hopes that in the future it can be used as a foundation for object oriented programming of applications based on FEM/BEM coupling. The object classes presented in the work are extensions of the class library of OSW -- Object Structural Workbench, a toolkit for developing object oriented modeling applications in science and engineering.
We introduce a novel liquid simulation approach that combines a spatially adaptive pressure proje... more We introduce a novel liquid simulation approach that combines a spatially adaptive pressure projection solver with the Particle-in-Cell (PIC) method. The solver relies on a generalized version of the Finite Difference (FD) method to approximate the pressure field and its gradients in tree-based grid discretizations, possibly non-graded. In our approach, FD stencils are computed by using meshfree interpolations provided by a variant of Radial Basis Function (RBF), known as RBF-Finite-Difference (RBF-FD). This meshfree version of the FD produces differentiation weights on scattered nodes with high-order accuracy. Our method adapts a quadtree/octree dynamically in a narrow-band around the liquid interface, providing an adaptive particle sampling for the PIC advection step. Furthermore, RBF affords an accurate scheme for velocity transfer between the grid and particles, keeping the system's stability and avoiding numerical dissipation. We also present a data structure that connects the spatial subdivision of a quadtree/octree with the topology of its corresponding dual-graph. Our data structure makes the setup of stencils straightforward, allowing its updating without the need to rebuild it from scratch at each time-step. We show the effectiveness and accuracy of our solver by simulating incompressible inviscid fluids and comparing results with regular PIC-based solvers available in the literature.
This paper presents a novel method to detect free‐surfaces on particle‐based volume representatio... more This paper presents a novel method to detect free‐surfaces on particle‐based volume representation. In contrast to most particle‐based free‐surface detection methods, which perform the surface identification based on physical and geometrical properties derived from the underlying fluid flow simulation, the proposed approach only demands the spatial location of the particles to properly recognize surface particles, avoiding even the use of kernels. Boundary particles are identified through a Hidden Point Removal (HPR) operator used for visibility test. Our method is very simple, fast, easy to implement and robust to changes in the distribution of particles, even when facing large deformation of the free‐surface. A set of comparisons against state‐of‐the‐art boundary detection methods show the effectiveness of our approach. The good performance of our method is also attested in the context of fluid flow simulation involving free‐surface, mainly when using level‐sets for rendering purposes.
The difficulty to understand the complex behavior of vector fields makes its visual segmentation ... more The difficulty to understand the complex behavior of vector fields makes its visual segmentation an area of constant interest in scientific visualization. In this paper, we present a novel interactive segmentation framework for discrete vector fields. In our method, the vector field domain is partitioned into multiple regions with same flow patterns. In order to accomplish this task, feature vectors are extracted from streamlines and mapped to a visual space using multidimensional projection. The interactivity with projected data in the visual space improves the results of the segmentation according to user's knowledge. The provided results and comparisons show the flexibility and effectiveness of our framework.
Figure 1: Fluid simulation with two-way interaction between rigid bodies Simulation of natural ph... more Figure 1: Fluid simulation with two-way interaction between rigid bodies Simulation of natural phenomena, such as water and smoke, is a very important topic to increase real time scene realism in video-games. Besides the graphical aspect, in order to achieve realism, it is necessary to correctly simulate and solve its complex governing equations, requiring an intense computational work. Fluid simu-lation is achieved by solving the Navier-Stokes set of equations, using a numerical method in CPU or GPU, independently, as these equations do not have an analytical solution. The real time simula-tion also requires the simulation of interaction of the particles with objects in the scene, requiring many collision and contact forces calculation, which may drastically increase the computational time. In this paper we propose an heterogeneous multicore CPU and GPU hybrid architecture for fluid simulation with two-ways of interac-tion between them, and with a fine granularity control over rigi...
This paper presents the use of GPU as a math co-processor in real-time applications, in special g... more This paper presents the use of GPU as a math co-processor in real-time applications, in special games and physics simulation. Game loop architecture is used to validate the use of GPU such as math and physics co-processor, thus it is shown by this paper a new game loop architecture that employs graphics processors (GPUs) for gen-eral-purpose computation (GPGPU). A critical issue in this field is the process distribution between CPU and GPU. The presented architecture consists in a model for distribution and our implemen-tation showed many advantages in comparison to other approaches without a GPGPU stage. The architecture presented here was mainly designed to support mathematics and physics on the GPU, therefore the GPU stage in the model proposed works to help the CPU such as a math co-processor. Nevertheless, any kind of generic computation can be adapted. The model is implemented in an open source game engine and results obtained using this platform are presented. Keywords:: game...
This paper presents a new architecture to implement any game loop models for games and real-time ... more This paper presents a new architecture to implement any game loop models for games and real-time applications that uses the GPU as a Mathematics and Physics co-processor, working in parallel pro-cessing mode with the CPU. The model applies concepts of auto-matic task distribution. The architecture can apply a set of heuris-tics defined in Lua scripts to get acquainted about what is the best processor for handling a given task. The model applies the GPGPU (General-Purpose Computation on GPUs) paradigm. The architec-ture that this work proposes acquires knowledge about the hardware by running tasks in each processor, and by studying their perfor-mance over time, learning about what is the best processor for a group of tasks.
Computer games are becoming an important resource for many educational purposes. The increase of ... more Computer games are becoming an important resource for many educational purposes. The increase of computational power and new paradigms of engine architectures not only reinforce this, but also make available new approaches to real time applications. It is also well known that interactive environments are strong mech-anisms for a more efficient content comprehension and assimila-tion. One of these fields is physics, where experimentations and real time interactions are desirable. Although there are many soft-ware and computational environments focused on physics learning, few programming tools offer the facility for programming appli-cations and experiments. This work presents a novel framework for physics programming that combines the facilities available in Microsoft XNA framework with C # and GPU acceleration. The present framework implements a complete set of functionalities for dynamic simulation of rigid bodies, encapsulating them completely with XNA.
This paper presents a new animation system initially designed for visualization of dynamics simul... more This paper presents a new animation system initially designed for visualization of dynamics simulations in science and engineering applications. A hybrid lan-guage is used to describe the scene objects to be ani-mated and the scripts and actions that modify the state of the objects over time. The system is made up of components responsible to compile and execute an animation, and render and exhibit the resulting frames. Currently, the animation system is being extended to support dynamic simulations of rigid and elastic bodies in interactive, real-time applications, including games. For rigid body simulations, AGEIA PhysX engine is used as a component. The paper presents the function-ality of the main components of the original system architecture, introduces the main features of the ani-mation language and describes how an animation is specified and then executed by the system.
ABSTRACT This paper introduces an object oriented approach to the boundary element method (BEM) a... more ABSTRACT This paper introduces an object oriented approach to the boundary element method (BEM) applied to solid elastostatic analysis. The proposed solution is made up of object classes which can be used for implementing object oriented programs of numerical analysis based on BEM. Furthermore, one hopes that in the future it can be used as a foundation for object oriented programming of applications based on FEM/BEM coupling. The object classes presented in the work are extensions of the class library of OSW -- Object Structural Workbench, a toolkit for developing object oriented modeling applications in science and engineering.
We introduce a novel liquid simulation approach that combines a spatially adaptive pressure proje... more We introduce a novel liquid simulation approach that combines a spatially adaptive pressure projection solver with the Particle-in-Cell (PIC) method. The solver relies on a generalized version of the Finite Difference (FD) method to approximate the pressure field and its gradients in tree-based grid discretizations, possibly non-graded. In our approach, FD stencils are computed by using meshfree interpolations provided by a variant of Radial Basis Function (RBF), known as RBF-Finite-Difference (RBF-FD). This meshfree version of the FD produces differentiation weights on scattered nodes with high-order accuracy. Our method adapts a quadtree/octree dynamically in a narrow-band around the liquid interface, providing an adaptive particle sampling for the PIC advection step. Furthermore, RBF affords an accurate scheme for velocity transfer between the grid and particles, keeping the system's stability and avoiding numerical dissipation. We also present a data structure that connects the spatial subdivision of a quadtree/octree with the topology of its corresponding dual-graph. Our data structure makes the setup of stencils straightforward, allowing its updating without the need to rebuild it from scratch at each time-step. We show the effectiveness and accuracy of our solver by simulating incompressible inviscid fluids and comparing results with regular PIC-based solvers available in the literature.
This paper presents a novel method to detect free‐surfaces on particle‐based volume representatio... more This paper presents a novel method to detect free‐surfaces on particle‐based volume representation. In contrast to most particle‐based free‐surface detection methods, which perform the surface identification based on physical and geometrical properties derived from the underlying fluid flow simulation, the proposed approach only demands the spatial location of the particles to properly recognize surface particles, avoiding even the use of kernels. Boundary particles are identified through a Hidden Point Removal (HPR) operator used for visibility test. Our method is very simple, fast, easy to implement and robust to changes in the distribution of particles, even when facing large deformation of the free‐surface. A set of comparisons against state‐of‐the‐art boundary detection methods show the effectiveness of our approach. The good performance of our method is also attested in the context of fluid flow simulation involving free‐surface, mainly when using level‐sets for rendering purposes.
The difficulty to understand the complex behavior of vector fields makes its visual segmentation ... more The difficulty to understand the complex behavior of vector fields makes its visual segmentation an area of constant interest in scientific visualization. In this paper, we present a novel interactive segmentation framework for discrete vector fields. In our method, the vector field domain is partitioned into multiple regions with same flow patterns. In order to accomplish this task, feature vectors are extracted from streamlines and mapped to a visual space using multidimensional projection. The interactivity with projected data in the visual space improves the results of the segmentation according to user's knowledge. The provided results and comparisons show the flexibility and effectiveness of our framework.
Figure 1: Fluid simulation with two-way interaction between rigid bodies Simulation of natural ph... more Figure 1: Fluid simulation with two-way interaction between rigid bodies Simulation of natural phenomena, such as water and smoke, is a very important topic to increase real time scene realism in video-games. Besides the graphical aspect, in order to achieve realism, it is necessary to correctly simulate and solve its complex governing equations, requiring an intense computational work. Fluid simu-lation is achieved by solving the Navier-Stokes set of equations, using a numerical method in CPU or GPU, independently, as these equations do not have an analytical solution. The real time simula-tion also requires the simulation of interaction of the particles with objects in the scene, requiring many collision and contact forces calculation, which may drastically increase the computational time. In this paper we propose an heterogeneous multicore CPU and GPU hybrid architecture for fluid simulation with two-ways of interac-tion between them, and with a fine granularity control over rigi...
This paper presents the use of GPU as a math co-processor in real-time applications, in special g... more This paper presents the use of GPU as a math co-processor in real-time applications, in special games and physics simulation. Game loop architecture is used to validate the use of GPU such as math and physics co-processor, thus it is shown by this paper a new game loop architecture that employs graphics processors (GPUs) for gen-eral-purpose computation (GPGPU). A critical issue in this field is the process distribution between CPU and GPU. The presented architecture consists in a model for distribution and our implemen-tation showed many advantages in comparison to other approaches without a GPGPU stage. The architecture presented here was mainly designed to support mathematics and physics on the GPU, therefore the GPU stage in the model proposed works to help the CPU such as a math co-processor. Nevertheless, any kind of generic computation can be adapted. The model is implemented in an open source game engine and results obtained using this platform are presented. Keywords:: game...
This paper presents a new architecture to implement any game loop models for games and real-time ... more This paper presents a new architecture to implement any game loop models for games and real-time applications that uses the GPU as a Mathematics and Physics co-processor, working in parallel pro-cessing mode with the CPU. The model applies concepts of auto-matic task distribution. The architecture can apply a set of heuris-tics defined in Lua scripts to get acquainted about what is the best processor for handling a given task. The model applies the GPGPU (General-Purpose Computation on GPUs) paradigm. The architec-ture that this work proposes acquires knowledge about the hardware by running tasks in each processor, and by studying their perfor-mance over time, learning about what is the best processor for a group of tasks.
Computer games are becoming an important resource for many educational purposes. The increase of ... more Computer games are becoming an important resource for many educational purposes. The increase of computational power and new paradigms of engine architectures not only reinforce this, but also make available new approaches to real time applications. It is also well known that interactive environments are strong mech-anisms for a more efficient content comprehension and assimila-tion. One of these fields is physics, where experimentations and real time interactions are desirable. Although there are many soft-ware and computational environments focused on physics learning, few programming tools offer the facility for programming appli-cations and experiments. This work presents a novel framework for physics programming that combines the facilities available in Microsoft XNA framework with C # and GPU acceleration. The present framework implements a complete set of functionalities for dynamic simulation of rigid bodies, encapsulating them completely with XNA.
This paper presents a new animation system initially designed for visualization of dynamics simul... more This paper presents a new animation system initially designed for visualization of dynamics simulations in science and engineering applications. A hybrid lan-guage is used to describe the scene objects to be ani-mated and the scripts and actions that modify the state of the objects over time. The system is made up of components responsible to compile and execute an animation, and render and exhibit the resulting frames. Currently, the animation system is being extended to support dynamic simulations of rigid and elastic bodies in interactive, real-time applications, including games. For rigid body simulations, AGEIA PhysX engine is used as a component. The paper presents the function-ality of the main components of the original system architecture, introduces the main features of the ani-mation language and describes how an animation is specified and then executed by the system.
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