Houdini 20.5 Nodes Dynamics nodes

Agent Look At 3.0 dynamics node

Defines a target that an agent can turn its head to look at.

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Since 19.5

This node is used together with Agent Look At Apply, which selects a target and adjusts the agent’s skeleton to look toward the target’s position. You should turn on the Apply Look Ats parameter when you use the Crowd Solver.

You can chain several Agent Look At nodes together to define multiple targets. For more procedural setups, set Target Type to Points to allow each point in the specified geometry to be considered a target.

Parameters

Activation

1 activates the node. 0 deactivates the node.

Target Name

A unique name for this target.

You can use this with Crowd Trigger DOP to activate a trigger based on the agent’s current target.

Group

The group of agents to modify.

Guide

When turned on, displays the guide geometry for the look at targets.

Target Type

Target Type

Specifies how to determine the target’s position.

Position

Uses the target position specified by the Position parameter.

Object

Computes the target position using the object’s transform specified by the Object path. If the object contains geometry, it also includes the centroid of the geometry.

Points

You can use each point in the specified geometry as a target. The standard instancing point attributes define the target’s position, orientation, and velocity. You can also use the agentlookat_targetscore float point attribute to scale the Score Multiplier per point.

Agents

You can use each agent in the crowd as a target. You can also use the agentlookat_targetscore float point attribute to scale the Score Multiplier per agent.

Object

The path to an object or SOP geometry.

This parameter is only available when Target Type is set to Object.

Position

A world space position for the look at target.

This parameter is only available when Target Type is set to Position.

Geometry Source

Specifies the geometry to use.

SOP

Use the SOP specified in the SOP Path parameter.

DOP Data

Use the DOP specified in the DOP Object parameter.

First Context Geometry

Use the SOP connected to the DOP network’s first input.

Second Context Geometry

Use the SOP connected to the DOP network’s second input.

Third Context Geometry

Use the SOP connected to the DOP network’s third input.

Fourth Context Geometry

Use the SOP connected to the DOP network’s fourth input.

SOP Path

The path to the SOP (when Geometry Source is set to SOP).

DOP Object

The name of the DOP object (when Geometry Source is set to DOP Data).

DOP Data

The data attached to the DOP Object (when Geometry Source is set to DOP Data).

Group

The group of points to look at (when Target Type is set to Points).

Max Search Points

The maximum number of nearby points to consider when selecting a point to look at.

This parameter is only available when Target Type is set to Points.

Group

The group of agents to look at (when Target Type is set to Agents).

Max Neighbors

The maximum number of nearest neighbors to consider when selecting an agent to look at.

This parameter is only available when Target Type is set to Agents.

Match by Attribute

When the Target Type is Points or Agents, only consider points for which the Target Attribute matches the agent’s value for the Agent Attribute. This can be useful to precisely control which target(s) an agent looks at.

The attributes can be an integer or string type. For string attributes, the Agent Attribute can be a string pattern that is matched against the Target Attribute value. For integer attributes, if the Target Attribute is not specified, the point number will be used instead.

Agent Attribute

The name of a string or integer point attribute on the crowd geometry.

Target Attribute

The name of a string or integer point attribute on the target geometry. When the Target Type is Agents, the target geometry is also the crowd geometry.

Target Visibility

Horizontal FOV

The maximum horizontal angle (in degrees) at which the target is visible.

Choose one of the options on this parameter to specify how the horizontal FOV is determined for each agent:

Set Value

Use the Horizontal FOV value.

Set from Attribute

Overrides the Horizontal FOV with the value of the point attribute, Horizontal FOV Attribute.

Scale by Attribute

Multiplies the Horizontal FOV with the value of the point attribute, Horizontal FOV Attribute.

Horizontal FOV Attribute

The point attribute on the agent. If the Horizontal FOV mode is Set from Attribute, Horizontal FOV Attribute is in radians.

This parameter is only available when the Horizontal FOV mode is set to Set from Attribute or Scale by Attribute.

Vertical FOV

The maximum vertical angle (in degrees) at which the target is visible.

Choose one of the options on this parameter to specify how the vertical FOV is determined for each agent:

Set Value

Use the Vertical FOV value.

Set from Attribute

Overrides the Vertical FOV with the value of the point attribute, Vertical FOV Attribute.

Scale by Attribute

Multiplies the Vertical FOV with the value of the point attribute, Vertical FOV Attribute.

Vertical FOV Attribute

The point attribute on the agent. If the Vertical FOV mode is Set from Attribute, Vertical FOV Attribute is in radians.

This parameter is only available when the Vertical FOV mode is set to Set from Attribute or Scale by Attribute.

Distance Range

Specifies the minimum and maximum distance that the target is visible. When Target Type is Points or Agents, the maximum distance limits the number of nearby points considered.

Target Score

Controls how interesting the target is to an agent based on factors such as distance, speed, or orientation. The scoring factors are normalized values (from 0 to 1), and the final score is computed as a weighted average. The Agent Look At Apply DOP selects the target with the highest score when an agent chooses a target to look at.

Distance Weight

The weight for the target’s distance score. Adjusts the importance of targets that are close to the agent. The distance score has a value of 1 at the minimum of the Distance Range, and a value of 0 at the maximum distance.

Periphery Weight

The weight for the target’s periphery score. Adjusts the importance of targets that are entering the edge of the field of view.

Relative Orientation Weight

The weight for the target’s orientation score. Adjusts the importance of targets that are facing towards the agent and are in the center of the field of view.

Relative Speed Weight

The weight for the target’s speed score, which is higher for targets that have a larger speed relative to the agent. Adjusts the importance of fast-moving targets. The speed score has a value of 0 at the minimum of the Relative Speed Range, and a value of 1 at the maximum speed.

Relative Speed Range

Specifies the minimum and maximum relative speeds, which determine the target’s relative speed score when the Relative Speed Weight is non-zero.

Score Multiplier

Scales the target’s overall score. You can manually adjust the importance of specific targets. When the Target Type is Points or Agents, this can be multiplied per point with the agentlookat_targetscore attribute.

Gaze Duration

Gaze Duration Time

Specifies the minimum and maximum time (in seconds) that the agent can look at this target. This allows the agent to lose interest in a target over time. After the minimum duration, the target’s score will gradually decrease, allowing the agent to switch to a target that has a higher score. After the maximum duration has elapsed, the agent will stop looking at the target.

Choose one of the options on this parameter to specify how the gaze duration is determined for each agent:

Set Value

Use the Gaze Duration Time value.

Set from Attribute

Overrides the Gaze Duration Time with the value of the point attribute, Gaze Duration Attribute.

Scale by Attribute

Multiplies the Gaze Duration Time with the value of the point attribute, Gaze Duration Attribute.

Gaze Duration Attribute

The point attribute on the agent. If the Gaze Duration Time mode is Set from Attribute, Gaze Duration Attribute has a tuple size of 2.

This parameter is only available when the Gaze Duration Time mode is set to Set from Attribute or Scale by Attribute.

Random Time Offset

Randomly increases the minimum gaze duration. This allows agents to start losing interest in the target at different times.

Random Seed

Seed used when randomly varying the gaze duration time.

Examples

AgentLookAtBasic Example for Agent Look At dynamics node

This example demonstrates several methods of defining look at targets, such as looking at other agents in the crowd or points from a point cloud.

See also

Dynamics nodes