koobas.hobune.stream
How to set ArticulationBody motion to "limited" in C#
I'm adding the ArticulationBody component to a GameObject at runtime, and I'm trying to figure out how to set the "Motion" type from Free to Limited.
The unity docs are really sparse and I can't figure out how to implement it. The closest thing I've found is https://docs.unity3d.com/ScriptReference/ArticulationBody-linearLockX.html. Through trial and error, I've implemented the following script which builds without errors, but "Motion" still shows up as "Free". If I manually set motion to "limited" in play mode, then the drive.lowerLimit and drive.upperLimit actually have an effect.
This script should work as-is, just attach to an empty GameObject.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Test : MonoBehaviour
{
void Start()
{
for (int i = 0; i < 3; i++)
{
// spawn ArticulationBody root
GameObject root = GameObject.CreatePrimitive(PrimitiveType.Sphere);
root.transform.position = new Vector3(0, 2f, 2f * i);
root.AddComponent<ArticulationBody>();
ArticulationBody abRoot = root.GetComponent<ArticulationBody>();
abRoot.mass = 20f;
// link
GameObject link = GameObject.CreatePrimitive(PrimitiveType.Cube);
float randomX = Random.Range(2f, 6f);
link.transform.localScale = new Vector3(randomX, 0.5f, 0.5f);
float pivotPoint = (randomX / 2) + (root.transform.localScale.x / 2);
link.transform.position = new Vector3(pivotPoint, 2f, 2f * i);
link.transform.SetParent(root.transform);
link.AddComponent<ArticulationBody>();
ArticulationBody ablink = link.GetComponent<ArticulationBody>();
ablink.mass = 0.25f;
ablink.anchorRotation = Quaternion.Euler(0, 180, 90);
ablink.anchorPosition = Vector3.left / 2;
ablink.jointType = ArticulationJointType.RevoluteJoint;
ArticulationDofLock limit = ArticulationDofLock.LimitedMotion;
ablink.linearLockX = limit;
var drive = ablink.xDrive;
drive.stiffness = 10000;
drive.damping = 100;
drive.lowerLimit = -90f; // has no effect unless "Motion" is set to "Limited" in the editor manually
drive.upperLimit = 90f; // has no effect unless "Motion" is set to "Limited" in the editor manually
drive.target = 0f;
ablink.xDrive = drive;
}
}
}
