Houdini 20.5 Nodes Geometry nodes

Crowd MotionPath Transition geometry node

Blends an agent’s motion path into a new animation clip.

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Since 20.0

This SOP transitions agents from one animation clip to another, blending the agent’s current motion path into a path built from the new clip’s locomotion.

See SOP motion paths for more information on the SOP Crowds MotionPath toolset.

Parameters

Group

The motion paths that transition into a new clip.

Trigger

Trigger Group

For each motion path, the transition begins at the first point along the path that is in this group.

Tip

The Crowd MotionPath Trigger SOP can be used to create many common types of triggers.

Combine Triggers

Combines the trigger with other existing triggers using boolean operations.

Boolean Operation (left drop-down box)

The boolean operation to perform (Union (Or), Intersect (And), Exclusive Or, or Subtraction).

Comparison (middle drop-down box)

Specifies whether to the perform the boolean operation on the trigger groups in the right drop-down box (With), or on all the trigger groups except those in the right drop-down box (With All But).

Trigger Group (right drop-down box)

A trigger or list of trigger group names.

Random Delay

Max Random Delay

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

Clips

Randomize Clips

When turned on, selects the agent’s clip from a weighted random distribution of clips. If Use Clip Transition Graph is turned on, clips are only considered if they can be reached through a sequence of transitions from the agent’s current clip.

Random Seed

The seed for randomly selecting clips when there are multiple Clip Groups, or when Clip Names is a list of clip names.

This parameter is available when Randomize Clips is turned on.

Clip Groups

A weighted random distribution of clips to transition agents to.

This parameter is available when Randomize Clips is turned on.

Clip Names

A string pattern that specifies one or more clip names. The pattern follows the same syntax as the match VEX function. The Weight value for the group is divided evenly between the matching clips.

This parameter is available when Randomize Clips is turned on.

Weight

Specifies how likely the clips are to be selected.

This parameter is available when Randomize Clips is turned on.

Clip Name

When Randomize Clips is turned off, this is the name of the clip to transition to.

Use Clip Transition Graph

When turned on, the agent’s clip transition graph may optionally be used to control transitions between animation clips. This can be used to delay transitions until an appropriate point in the current animation clip, make use of intermediate transition clips, and provide information about how to smoothly blend into the new clip.

Additionally, the clip transition graph allows per-clip control over this behavior, which is useful if the new clip is being randomly selected from a list of clips.

The clip transition graph geometry is expected to be stored in the agent’s shape library as a shape named __transitiongraph__.

Blend Frames

When Use Clip Transition Graph is turned off, this is the number of frames over which to blend into the new animation clip.

Initial Clip Time

When Use Clip Transition Graph is turned off, this is the initial clip time (in the Clip Time Units, relative to the clip’s start time) for the new clip.

Clip Time Units

This drop-down menu specifies the units of the Initial Clip Time and Random Clip Offset.

Seconds

The clip time is specified in seconds, relative to the clip’s start time.

Phase

The clip time is specified as a normalized phase, where 0 is the beginning of the clip, and 1 is the end of the clip. This can be simpler to use when working with clips of different lengths.

Random Clip Offset

When turned on, this randomly shifts the Initial Clip Time forward for each agent by up to the specified amount. This parameter is available when Use Clip Transition Graph is turned off.

Clip Offset Seed

When Random Clip Offset is turned on, this seed is used when randomly varying clip times.

Clip Speed

A multiplier for how fast the animation clip is played back.

Clip Speed Mode

This drop-down menu controls whether the clip speed is randomized or overridden by a point attribute on the input agents.

Set Uniform

Each agent’s clip speed is set to the Clip Speed.

Set Varying

Each agent’s clip speed is randomized according to the Variance (%) and Variance Seed.

Use Attribute

Each agent’s clip speed is set from a point attribute on the input geometry.

Variance (%)

When the Clip Speed Mode is set to Set Varying, this is the percentage that the Clip Speed can be randomly increased or decreased by. For example, if the Clip Speed is 0.7 and the Variance is 10%, the agents' clip speeds will be random values between 0.63 and 0.77.

Variance Seed

When the Clip Speed Mode is set to Set Varying, this seed is used when randomly varying clip speeds.

Clip Speed Attribute

When the Clip Speed Mode is set to Use Attribute, this is the name of a float point attribute to set the clip speed from.

Attributes

State Attribute

When turned on, this string point attribute is set to the Output State for the post-transition points on the motion paths. This can be used to tag the affected points with a descriptive name for the agents' new state (for example, running).

Tip

A group pattern such as @state=running can be used to select points based on the value of this attribute.

Output State

The new value of the State Attribute for any motion path points after the transition has completed.

Inputs

Motion Paths

Polyline curves representing the paths of the agents over a time range.

Agents

A crowd of agents whose motion is represented by the Motion Paths.

Outputs

Motion Paths

Polyline curves representing the paths of the agents over a time range.

Agents

A crowd of agents whose motion is represented by the Motion Paths.

Examples

MotionPathTransitionClips

This example demonstrates how to use the Crowd MotionPath Transition SOP to blend between animation clips, including intermediate transition clips defined by a clip transition graph

See also

Geometry nodes