Houdini 17.5 Nodes Dynamics nodes

POP Steer Wander dynamics node

Apply forces to agents/particles to create a random motion.

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This is a crowd behavior node, but you can also use it on regular particles (see the Output attribute parameter).

This node has a Force parameter, which controls the base speed of the wander, and Amplitude, which controls the size of the changes to the base speed. So, for example, high Force and low Amplitude would give fast motion with small deviations, while low Force and high Amplitude would give overall slower motion but with big swings in direction and speed.



When this is off, the node will have no effect. You can animate this to turn the behavior on or off at different times.


Only modify a certain group or groups out of all agents/particles. You can name groups of agents using the Group name parameter on the Crowd Source geometry node.

Output Attribute

If you are working with agents, set this to "Crowds steerforce". If you are working with particles, set this to "POP force".

This controls whether the node modifies the agent’s steerforce attribute (used by the crowd solver) or the particle’s force attribute (used by the POP solver).


Available when Output attribute is "Crowd steerforce". This number is used by the crowd solver to normalize and scale multiple forces that apply to an agent.


Base strength of the wander force.


Whether to use 2D noise or 3D noise.


Swirl Size

Swirl Scale

Pulse Length





The following examples include this node.

Street Crowd Example Example for Crowd Solver dynamics node

Crowd example showing a street setup with two agent groups

The setup creates two groups of agents. The yellow agents are zombies which follow a path of the street. The blue agents are living pedestrians that wander around until they come into proximity of the zombies and then they swtich into a running state.

Triggers to change agent states are setup in the crowd_sim dopnet. The zombies group uses proximity to the stoplights and the color of the light to transition into a standing state when lights are red. The living group transition into a running state when they get close to the zombie agents.


The animation clips need to be baked out before playing the scene. This should happen automatically if example is created from Crowds shelf. Otherwise save scene file to a location of your choice and click Render on '/obj/bake_cycles' ropnet to write out the files. The default path for the files is ${HIP}/agents.

CrowdPov Example for Agent Cam object node

This example demonstrates how the agent cam can be assigned to a crowd agent to give you the point of view from someone in a crowd simulation.

AgentRelationshipBasic Example for Agent Relationship geometry node

This example demonstrates how to create a simple parent-child agent setup.

SimpleCrowdCloth Example for Agent Vellum Unpack geometry node

This example demonstrates a simple workflow for simulating cloth on a crowd of characters using the Vellum solver.

Fuzzy Logic State Transition Example Example for Fuzzy Defuzz VOP node

This example shows a crowd setup where the state transition is triggered on a fuzzy network setup.

See also

Dynamics nodes