PhysX FleX is a particle based simulation technique for real-time visual effects. Traditionally, visual effects are made using a combination of elements created using specialized solvers for rigid bodies, fluids, clothing, etc. Because FLEX uses a unified particle representation for all object types, it enables new effects where different simulated substances can interact with each other seamlessly. So far we showed examples for rigid body stacking, particle piles, soft bodies and fluids. In the video below we'll be showing some of the new advancements within PhysX FleX.


Cereal Simulation

The simulation shows two way coupling of cereal represented by rigid bodies with particle based fluid simulation. The milk is represented by up to 100.000 particles, surface tension and viscous forces are modeled and because the cereal pieces have a lower density than milk they naturally rise to the surface due to buoyancy. The milk surface is rendered in real time using ellipsoid splatting and a sub-surface scattering approximation.

Milk and Cereal
No Gravity
Particle View


Smoke Simulation

In the smoke simulation the underlying fluid is modeled by thousands of particles tracking velocity and vorticity. Using particles provides a sparse representation of the air flow and allows smoke to interact with the other particle based objects. Because this is a grid free method there are no fixed boundaries on the fluid flow.
For rendering we advect hundreds of thousands of smoke particles through the underlying velocity field and render them with shadowing and a single scattering shader.

Realistic Smoke
Rigid Body / Smoke Interaction
Rigid Body / Cloth / Smoke Interaction


Additional Examples

Here are more examples of how FleX could be used.

Wind Tunnel
High Viscosity Fluids
Fluid-Fluid Interaction



PhysX FleX is currently in closed beta and available for early adopters. Please contact us for Licensing inquiries. We are also working on a UE4 integration.