Houdini 20.0 Nodes Geometry nodes

Agent Constraint Network geometry node

Builds a constraint network to hold an agent’s limbs together.

Since 14.5

This node will create a constraint for each transform in the agent’s collision layer that has a shape attached to it. The rotation limits set up by the Agent Configure Joints node will be used to set up cone twist constraints. For any transforms where the rotation limits were not set (or if there are multiple root collision shapes), pin constraints will be created to prevent the ragdoll from immediately separating.

Parameters

Group

The agents to create constraints for.

Pin Root Collision Shapes

If there are multiple root collision shapes, pin constraints will be created to hold those objects together.

Pin Shapes With No Rotation Limits

If there is a shape whose joint did not have a rotation limit set, a pin constraint will be created to attach it to its parent.

Random Seed

Seed used when adding random variation to the cone twist constraints' parameters.

Softness

Once an angle is greater than softness times the maximum angle, the constraint begins to take effect. Lowering the value of softness softens the constraint boundaries. However, values that are too small can cause a “popping” effect at the start of the simulation for joints that are near their rotation limits and are past the softness threshold.

Randomness

Specifies how much the Softness can be randomly varied by.

Constraint Force Mixing

Increase this to make the constraint spongier, and potentially increase the stability of the simulation. The constraint may be violated by an amount proportional to the force required to re-establish the constraint, times this parameter.

Randomness

Specifies how much the Constraint Force Mixing can be randomly varied by.

Bias Factor

The rate at which the constraint corrects errors in position or orientation. A value of 1 will ensure that the constraint is always obeyed. It is recommended to keep bias between 0.2 and 0.5.

Randomness

Specifies how much the Bias Factor can be randomly varied by.

Relaxation Factor

The rate at which the angular velocity is changed by the constraint. A low value means the constraint will modify the velocities slowly, leaving the boundaries appearing softer.

Randomness

Specifies how much the Relaxation Factor can be randomly varied by.

Position CFM

Increase this to make the constraint spongier, and potentially increase the stability of the simulation. The position component of the constraint may be violated by an amount proportional to the force required to re-establish the constraint, times this parameter.

Randomness

Specifies how much the Position CFM can be randomly varied by.

Position ERP

Specifies what proportion of the position error will be fixed during the next simulation step. A value between 0.1 and 0.8 is recommended for most simulation.

Randomness

Specifies how much the Position ERP can be randomly varied by.

See also

Geometry nodes