Abstract: A simulation engine performs a mass-conserving Eulerian fluid simulation by manipulating the distribution of density between nodes associated with the fluid simulation. The simulation engine traces a velocity field upstream to identify the source of mass that currently resides at a given node. The simulation engine then adjusts (i) the density contributions to that source from adjacent nodes and (ii) the density contributions provided by that source to the given node. In doing so, the simulation engine maintains conservation of mass at a local level between nodes within a given neighborhood. As a result, mass is conserved at a global level. One advantage of the disclosed technique is that a fluid interface associated with the fluid simulation may appear physically realistic, because numerical errors typically caused by violations of conservation of mass may be eliminated.

Abstract: A method and system of representing and simulating an object by representing using with velocity-dependent particles.

Abstract: One embodiment of the present invention sets forth an Eulerian fluid simulation technique which enables real-time simulations of large scale three dimensional fluid volumes that include free surface water. A hybrid grid representation composed of regular cubic cells on top of a layer of tall cells is used to reduce computation time. Water above an arbitrary terrain can be represented without consuming an excessive amount of memory and compute power, while focusing simulation effort on the area near the surface of the water to produce accurate results. Additionally, the grid representation may be optimized for a graphics processor implementation of the fluid solver.

Abstract: A simulation engine is configured to generate a physical simulation of a chain of particles by implementing a physics-based algorithm. The simulation engine is configured to generate a predicted position for each particle and to then adjust the predicted position of each particle based on a set of constraints associated with the physics-based algorithm. The simulation engine may then generate a predicted velocity for a given particle based on the adjusted, predicted position of that particle and based on the adjusted, predicted position of an adjacent particle.

Abstract: A method and system of representing and simulating an object by representing using with velocity-dependent particles.

Abstract: One embodiment of the present invention sets forth multigrid generation technique which enables accurate simulations of large scale three dimensional (3D) fluid volumes. A model of the fluid to be simulated is represented using a cell grid. The generated multigrid provides a hierarchy of increasingly coarser representations of the model that are used by a pressure solver. Eulerian simulation techniques require solving a linear system to determine pressure values for each cell within the cell grid. Different levels of the multigrid are then used to compute the pressure values for different regions of the model, maintaining accuracy near the surface of the fluid while simplifying the computations. The accurate pressure values ensure that the simulation produces detailed features of the water movement. Additionally, the multigrid pressure solver may be optimized for execution by a graphics processor.

Abstract: A method is provided for depicting on a display, an object within a simulated environment having clothing. In this method, the clothing is represented as a series of vertices that include vertices that are attached to the object and vertices that are not attached to the object. The method improves upon position based dynamics algorithm by constraining unattached vertices to be a predefined distance away from attached vertices that are connected thereto to compensate for overstretching in the simulated clothing.

Abstract: A simulation engine performs a mass-conserving Eulerian fluid simulation by manipulating the distribution of density between nodes associated with the fluid simulation. The simulation engine traces a velocity field upstream to identify the source of mass that currently resides at a given node. The simulation engine then adjusts (i) the density contributions to that source from adjacent nodes and (ii) the density contributions provided by that source to the given node. In doing so, the simulation engine maintains conservation of mass at a local level between nodes within a given neighborhood. As a result, mass is conserved at a global level. One advantage of the disclosed technique is that a fluid interface associated with the fluid simulation may appear physically realistic, because numerical errors typically caused by violations of conservation of mass may be eliminated.

Abstract: A physics simulation engine simulates the motion of one or more particles that represent virtual objects in a virtual graphics scene. Each particle is assigned to a level in a particle hierarchy that has at least two levels. The physics simulation engine collapses constraints associated with particles assigned to a first level of the particle hierarchy to generate hierarchical constraints associated with particles assigned to the second level of the particle hierarchy. The physics simulation engine updates the position of each particle assigned to the second level of the particle hierarchy by enforcing constraints associated with the particle. The physics simulation engine then updates the position of each particle assigned to the first level of the particle hierarchy based on the positions of the particles assigned to the second level of the particle hierarchy.

Abstract: A method of executing a physics simulation is performed in a system comprising a computational platform, a main application stored in the computational platform, a secondary application stored in the computational platform, and a cloth application programming interface (API) implemented in the computational platform. The method defines a cloth simulation call in the cloth API, and by operation of the main application, invokes a software routine using the cloth simulation call. Additionally, by operation of the secondary application, a state of the physics simulation is updated in response to the software routine.

Abstract: A method of stimulating a deformable object comprises modeling deformable elasticity for the object by defining an actual shape and a goal shape and pulling points in the goal shape towards corresponding points in the goal shape.

Abstract: A method is provided for depicting on a display, an object within a simulated environment having clothing. In this method, the clothing is represented as a series of vertices that include vertices that are attached to the object and vertices that are not attached to the object. The method improves upon position based dynamics algorithm by constraining unattached vertices to be a predefined distance away from attached vertices that are connected thereto to compensate for overstretching in the simulated clothing.

Abstract: A simulation engine is configured to generate a physical simulation of a chain of particles by implementing a physics-based algorithm. The simulation engine is configured to generate a predicted position for each particle and to then adjust the predicted position of each particle based on a set of constraints associated with the physics-based algorithm. The simulation engine may then generate a predicted velocity for a given particle based on the adjusted, predicted position of that particle and based on the adjusted, predicted position of an adjacent particle.

Abstract: One embodiment of the present invention sets forth multigrid generation technique which enables accurate simulations of large scale three dimensional (3D) fluid volumes. A model of the fluid to be simulated is represented using a cell grid. The generated multigrid provides a hierarchy of increasingly coarser representations of the model that are used by a pressure solver. Eulerian simulation techniques require solving a linear system to determine pressure values for each cell within the cell grid. Different levels of the multigrid are then used to compute the pressure values for different regions of the model, maintaining accuracy near the surface of the fluid while simplifying the computations. The accurate pressure values ensure that the simulation produces detailed features of the water movement. Additionally, the multigrid pressure solver may be optimized for execution by a graphics processor.

Abstract: One embodiment of the present invention sets forth a geometric multi-grid technique which enables accurate simulations of three dimensional (3D) fluid volumes. A model of the fluid to be simulated is represented using a cubic cell grid. The geometric multi-grid is generated to provide a hierarchy of increasingly coarser representations of the model that are used by a fluid pressure solver. During fluid simulations, the linear complementarity problem (LCP) resulting from discretizing the Poisson equation, subject to separating solid boundary conditions, is solved using the geometric multi-grid. Visual artifacts such as liquid sticking to a bounding surface are minimized and the computations performed to solve the LCP are simplified.

Abstract: One embodiment of the present invention sets forth an Eulerian fluid simulation technique which enables real-time simulations of large scale three dimensional fluid volumes that include free surface water. A hybrid grid representation composed of regular cubic cells on top of a layer of tall cells is used to reduce computation time. Water above an arbitrary terrain can be represented without consuming an excessive amount of memory and compute power, while focusing simulation effort on the area near the surface of the water to produce accurate results. Additionally, the grid representation may be optimized for a graphics processor implementation of the fluid solver.

Abstract: One embodiment of the present invention sets forth a technique for efficiently simulating breaking waves in real-time. A two-dimensional shallow water height field simulation generates height and velocity information used to generate a wave line for each wave within the height field that satisfies criteria for overturning. For each overturning wave, a wave sheet is created from particles generated relative to points on the respective wave line. Each wave sheet may move separately from an underlying wave that gave rise to the wave sheet, allowing the wave sheet to fall and break, creating a realistic appearance. As a falling wave sheet collides with the underlying wave or water surface, free particles may be generated to simulation spray visible on a real breaking wave.

Abstract: One embodiment of the present invention sets forth a technique for computing two-way rigid body coupling in a two-dimensional height field simulation, such as a shallow water simulation. Coupling from a rigid body to a fluid is computed using fluid displacement of the body in each grid cell. The body is projected onto a simulation plane to determine which grid cells are covered by the body. Fluid displacement from the body is computed for each grid cell based on displacement within a corresponding vertical column of fluid. Fluid displacement is distributed to neighboring grid cells prior to a height field computation. Coupling from the fluid to the rigid body is computed by integrating forces imparted on the body by the fluid at each grid cell. The integrated forces are used to compute a new position for the body in a subsequent simulation time step.

Abstract: Disclosed is a method of generating a three-dimensional (3D) surface defined by a boundary of a 3D point cloud. The method comprises generating density and depth maps from the 3D point cloud, constructing a 2D mesh from the depth and density maps, transforming the 2D mesh into a 3D mesh, and rendering 3D polygons defined by the 3D mesh.

Abstract: A method of simulating a deformable object comprises modeling deformable elasticity for the object by defining an actual shape and a goal shape and pulling points in the goal shape towards corresponding points in the goal shape.