Houdini 16.5 Particles

Limiting particle speed

There are three ways to control speed of particles. You can use Drag, Speed Limit, or Wind.

To...Do this

Apply drag to particles

  1. Click the Drag button on the Drive Particles tab.

  2. Click the particle system you want to be affected and press Enter to confirm your selection.

  3. Specify the node settings in the operation controls toolbar or parameter editor.

Set a high and low limit on the speed of particles

  1. Create a Speed Limit node and connect the particle flow to it.

  2. In the Speed limit parameter, set the minimum speed (the field on the left) and the maximum speed (the field on the right). Use a negative value to turn off a limit.

    The limits are not actually imposed until the particle is moved during post frame processing of its default velocity rule (see the Suppress Rule POP).

Push particles up to, but not past, a certain speed

  1. Click the Wind button on the Drive Particles tab of the shelf.

  2. Click the particle system you want to be affected and press Enter to confirm your selection.

    The Wind POP simulates a pushing force like wind, that can increase the velocity of particles but not past its own speed.

  3. Set the Wind vector. The direction of the vector controls the direction of the wind, and the length of the vector controls the intensity of the wind.

    For example, a value of (0, 1, 0) would create wind traveling straight down. A value of (0, 2, 0) would represent wind traveling in the same direction but twice as strong.

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