Houdini 20.0 Nodes Geometry nodes

Test Simulation: Crowd Transition geometry node

Provides a simple crowd simulation for testing transitions between animation clips.

Since 15.5

Parameters

Transition

Max Random Delay

When turned on, specifies the maximum delay (in seconds) between when the trigger evaluates to true and when the transition begins. This is useful to avoid having many agents start the transition at the same time.

Random Seed

When Max Random Delay is turned on, this specifies the seed used when selecting a random delay time.

Initial Clip

The name of the agents' initial animation clip.

Mode

Specifies how the sequence of clip transitions is determined.

Custom Sequence

Follows an explicit sequence of clip transitions, according to the Clip Sequence parameter.

Random

Randomly selects a clip to transition to from the current clip, based on the transition graph. This process will occur continuously unless a clip is reached that cannot transition to any other clips. This can be useful for easily previewing a large number of transitions.

Clip Sequence

Specifies an ordered sequence of clips to transition to, starting from the Initial Clip.

Clip

The name of the animation clip to transition to.

Trigger Frame

Specifies when to activate the trigger and begin transitioning to this clip.

Random Seed

Random seed used when selecting a clip to transition to.

Frames Between Triggers

Specifies the number of frames to wait before triggering the next random clip transition.

Terrain

Show Guide Geometry

When turned on, displays guide geometry indicating the positions of the lower limb joints and whether the feet are locked.

Scale

Adjusts the size of the guide geometry.

Color

Specifies the color of the guide geometry. When Enable Foot Locking is turned on, the color ramp indicates when the ankle and toe joints are locked or blending out of the locked position.

Enable Foot Locking

When turned on, prevents the ankle and toe from sliding when the foot should be planted. The channels specified on the Agent Prep SOP are used to determine when the foot should be planted during the animation clip, as well as how to blend out of the locked position. This option also improves terrain adaptation for situations where the unadjusted foot position is above the terrain, since the solver can distinguish between when the foot should be planted and when the foot is actually supposed to be above the ground. This option may still be used if no terrain object is specified.

The optional agentterrainadaptation_footdown float array point attribute can be used to override the foot down values computed from the agent’s animation clips. The attribute is expected to contain a replacement foot down value for each entry in the agentrig_footchannels point attribute. This may be useful when applying terrain adaptation to cached agents.

Adjust Hips

When turned on, adjusts the position of the hips to ensure that the legs are not over-stretched when planting the feet on uneven terrain.

Hip Offset

Specifies an additional offset to shift the hips up or down.

Hip Shift Per Frame

When turned on, specifies how much the hips can be shifted by in a single frame. This can reduce sudden hip motion on uneven terrain.

Knee Damping Threshold (%)

When the distance from the upper leg to the target ankle position is greater than this percentage of the maximum leg length, the knee angle will be damped so that it smoothly approaches a 180 degree angle as the target ankle position is extended. This can prevent the knee from popping when the leg is almost fully extended.

Note

This can allow the leg to stretch slightly, as keeping the foot planted on the terrain is a higher priority.

Enable Terrain Projection

When turned on, projects the agent particles on the given terrain.

Mode

Controls the direction of the terrain projection.

Direction Vector

Use the direction specified in Direction.

Up Attribute

Use the agent’s up attribute.

Offset

Additional offset that will shift all the agents up or down.

Enable Terrain Adaptation

When turned on, adjusts the agents' legs to conform to the terrain.

Lean Angle Per Frame

When navigating uneven terrain, the agent can lean forward or backward. When turned on, this parameter specifies the maximum angle (in degrees) that the agent can tilt in a single frame.

Backward Lean

Specifies how far (in degrees) the agent can lean backward.

Forward Lean

Specifies how far (in degrees) the agent can lean forward.

Guides

Before Transition

Specifies a color for agents that have not started the transition.

Pending Transition

Specifies a color for agents that are waiting to begin the transition (e.g. until they reach a certain time range in their animation clip).

During Transition

Specifies a color for agents that are currently transitioning between the two states.

After Transition

Specifies a color for agents that have finished the transition.

Simulation

Reset Simulation

Clears the entire simulation cache.

Sub Steps

Specifies the number of substeps the DOP simulation should perform each frame.

Start Frame

Specifies the frame at which the simulation will start cooking.

Scale Time

Specifies a scale factor that relates global time to the simulation time for the DOP network.

See also

Geometry nodes