Dynamics Operator 


Hair dynamics tutorial

Ornatrix provides a robust solution for simulating hair motion. We use a fully GPU-driven solution based on NVidia Flex technology to provide fast results which can be adjusted in real-time inside the viewport. Numerous parameters are used to control and style the behavior of hair to your liking. Both, short fur and long hair can be simulated with realism and simplicity.

External forces can be specified using Maya's native force fields. Hair can collide with the distribution surface and external collision objects can be added from the scene.

 

Supported Systems 

  • Ornatrix dynamics is supported on Windows and Linux operating systems. It is not supported on Macintosh.
  • You need a CUDA Compute 3 or newer compatible video card to use dynamics.
 

Creating the simulation 

To simulate your hair simply add the Dynamics operator to the hair stack on top of your hair or guides. Once the operator is added, play or scrub the scene time line to see the strands moving.

The Dynamics operator can be added anywhere in the stack and its output will be processed by operators above it. For example, you can simulate the dynamics on your hair guides and then generate the dense hair from these guides. The resulting hair can further be styled using other operators.

 

Adjusting simulation parameters 

Inside the Attribute Editor you can adjust various simulation parameters. Some of these parameters, such as Sub-steps and Iterations, affect the simulator itself. Other parameters like Density and Particle Size affect the properties of the simulated hair. Parameters like Dampening and Gravity affect the forces which act on the hair.

 

Recording the simulation 

Once you have tailored the simulation to your liking you can record the results. This will bake the simulation into the scene allowing backward and forward playback and significantly speeding up the evaluation of the operator. The results of the baked simulation will be stored with the scene.

To record the simulation set the start and end of your current scene timeline to match the part of the simulation you want to record and then press the Record Active Timeline button.

Once recorded, you can press the same button again to clear the recording and go back into live simulation mode.

 

Limitations 

  • Ornatrix dynamics has a limitation of 1.3 million hair particles. Typically a single strand can have on the order of 2-50 particles. This means that the number of simulated strands would be limited to roughly between 26,000 - 600,000.
  • Only one deforming collision object can be present inside a simulation. If the distribution mesh is deforming the additional external collision meshes will be approximated and simulated as convex objects or static triangular meshes (depending if they are animated or not). If distribution mesh is not deforming then one of the external collision objects can deform. Signed Distance Fields are used to approximate and simulate deforming collision geometry.