PhysX World Helper

Subframe Type - The simulation uses the Particle Flow System integration step as a timing parameter for each step of the simulation. To add extra precision for simulation purposes, you can subdivide the system integration step into smaller simulation intervals in one of two ways:

• Fixed - Uses the Subframe Factor setting (see following) to subdivide the system integration step.

• Variable - The PhysX Engine determines the best way to subdivide and define the step interval.

Tip: For stable, reproducible simulation in conjunction with PhysX Glue, it is strongly recommended that you use the Fixed subframe type.

Subframe Factor - When Subframe Type=Fixed, this setting tells Particle Flow how to subdivide the system integration step into smaller simulation intervals. A Subframe Factor value of 1 means that no additional subdivision occurs; 2 means that the main integration step is halved for physics simulation purposes, and so on.

Tip: If you encounter instability in your simulation, such as objects moving when they shouldn't, you probably need to increase the Subframe Factor value. The general rule of thumb for setting Subframe Factor is to double the Max Binds p/Particle value and add 2. So, if Max Binds p/Particle is 4, then Subframe Factor should be set to (2 x 4) + 2=10.

Sometimes you can get away with a lower Subframe Factor value, depending on the overall complexity of your simulation. In general, you need to experiment to find the best setting.

Example 1:  PhysXWorldHelper_SubframeType.zip

Example 2:  PhysXWorldHelper_SubframeFactor.zip