Archive for the ‘PB Fluids’ tag
About a month ago, NVIDIA has revealed a new unified GPU accelerated physics framework – NVIDIA FLEX – at “The Way It’s Meant To Be Played” press event in Montreal.
Today, Miles Macklin, physics programmer at NVIDIA and lead-developer of the FLEX system, has joined us to share first-hand details about this exciting technology.
PhysXInfo.com: So what is the NVIDIA FLEX exactly ? What are the main features of FLEX ?
Miles Macklin: FLEX is a multi-physics solver for visual effects.
It grew out of the work I did on Position Based Fluids, which was later extended to support two-way coupling between liquids and different object types such as clothing and rigid bodies.
The feature set is largely inspired by tools like Maya’s nCloth and Softimage’s Lagoa. The goal is to bring the capabilities of these off-line applications to real-time games.
Our readers may remember Position Based Fluids – new and promising fluid simulation approach, which has got quite a bit of attention few months ago.
Miles Macklin, one of the authors of the PB Fluids method, has presented latest improvements to the algorithm at SIGGRAPH 2013 conference – namely, two-way interaction with rigid bodies and cloth objects, as showcased in the videos below.
* Two-Way Coupling with Rigid Bodies
Position Based Fluids – this fluid simulation technology has indeed got some attention lately, and now, new “Position Based Fluids” paper by Miles Macklin (NVIDIA) and Matthias Müller-Fischer (NVIDIA) can give one a proper insight on the algorithm.
In fluid simulation, enforcing incompressibility is crucial for realism; it is also computationally expensive. Recent work has improved efficiency, but still requires time-steps that are impractical for real-time applications.
In this work we present an iterative density solver integrated into the Position Based Dynamics framework (PBD). By formulating and solving a set of positional constraints that enforce constant density, our method allows similar incompressibility and convergence to modern smoothed particle hydrodynamic (SPH) solvers, but inherits the stability of the geometric, position based dynamics method, allowing large time steps suitable for real-time applications.
We incorporate an artificial pressure term that improves particle distribution, creates surface tension, and lowers the neighborhood requirements of traditional SPH. Finally, we address the issue of energy loss by applying vorticity confinement as a velocity post process.
Many of you may have already seen an impressive real-time destruction and fluid simulation demo from GDC 2013.
Update: Position Based Fluids explained
We won’t talk about fracturing technology today, instead, let’s focus on the new fluid simulation algorithm, presented in the demo – it is known as Position Based Fluids.
Position Based Fluids is a way of simulating liquids using Position Based Dynamics (PBD), the same framework that is utilized for cloth and deformables simulation in PhysX SDK.
Because PBD uses an iterative solver, it can maintain incompressibility more efficiently than traditional SPH fluid solvers. It also has an artificial pressure term which improves particle distribution and creates nice surface tension-like effects (note the filaments in the splashes). Finally, vorticity confinement is used to allow the user to inject energy back to the fluid.
More details on this a new technique will be available later on, in a SIGGRAPH 2013 paper “Position-Based Fluids” by Miles Macklin and Matthias Mueller-Fischer, and we also expect it to be included in future versions of PhysX SDK or APEX modules.