Unity 5.0 Physics Freeze rotation not working

Question

I've set freeze rotation on my objects to true, but for some reason whenever they bounce off a wall or finish moving they are rotating. I just recently upgraded my project from 4.3 to 5.0. Before I updated, the physics was working fine and I never had this problem. I've changed several settings, but I can't seem to fix it.

Each of the objects is using a capsule collider, and they have rigidbodies set to interpolate and continuous dynamic with freeze rotation on for each axis.

Has anyone else run into this problem?

Answer 1

Answer by SergeMos · Jan 20, 2016 at 12:39 PM

I resolve the problem this way

void FixedUpdate(){ Vector3 oldRot = transform.rotation.eulerAngles; transform.rotation= Quaternion.Euler(oldRot.x, 90,oldRot.z); } (Fixed Y)

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x4000 · May 31, 2016 at 07:31 PM 1

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Yes, in FixedUpDate this does seem to work. Essentially the same thing, but on a rigidbody. Thanks!

 Quaternion rot = Quaternion.Euler( 0, r.rotation.eulerAngles.y, 0 );
         r.rotation = rot;

Answer 2

Janis I went ahead and got a substitute constraint script to work. My scripting issue was I was changing the transform in other places during FixedUpdate, so I had to move my changes into Update to constrain them.

It also let me set Min and Max rotations and allow for custom recovery speeds (so it turns back forward (quickly) instead of just locking down, it looks more realistic in the end).

Here is a copy of my code if it helps.

 #pragma strict
 
 private var baserot: Vector3;
 var xreturnspeed: float;
 var yreturnspeed: float;
 var zreturnspeed: float;
 
 var xmin : float;
 var xmax : float;
 
 
 
 
 function Start () {
 //saves the initial rotation for use as the "home" rotation.
     baserot = transform.rotation.eulerAngles;
     print (baserot);
 }
 
 function Update () {
     
     //rotates back to home on the Y axis at yreturnspeed over deltaTime
     //I use this with a very fast return speed because I want minimal deviation on Y, you might want to set and min and max similar to what is in my Fixed Update.
     var wantedrotation = Vector3(transform.rotation.eulerAngles.x, baserot.y, transform.rotation.eulerAngles.z); 
      transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.Euler(wantedrotation), Time.deltaTime * yreturnspeed);
 
 };
 
 function FixedUpdate () {
     //the rest is X constraint with min and max, I used this with a slower return because in other scripts I have rotation on X when moving.
     
     if(transform.rotation.x < xmin) {
         transform.rotation.x = xmin;
     }
     else if (transform.rotation.x > xmax) {
         transform.rotation.x = xmax;
     }
     
 
     var wantedrotation = Vector3(baserot.x, transform.rotation.eulerAngles.y, transform.rotation.eulerAngles.z); 
      transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.Euler(wantedrotation), Time.deltaTime * xreturnspeed);
  
 }

Answer 3

Answer by beautyfullcastle · Aug 06, 2015 at 12:52 PM

I had a same problem. So I fixed it with this code. And It rotate only y axis.

function FixedUpdate() { GetComponent.().rotation.x = 0f; GetComponent.().rotation.z = 0f; }

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x4000 · May 31, 2016 at 07:25 PM 0

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I did much the same, like this:

         Quaternion rot = r.rotation;
         rot.x = 0;
         rot.z = 0;
             r.rotation = rot; 
 
             rot = this.transform.rotation;
             rot.x = 0;
             rot.z = 0;
             this.transform.rotation = rot;

However, this can sometimes cause a strange "rotation quaternions must be unit length" issue.

Sprite101 x4000 · Jun 01, 2016 at 05:45 AM 1

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Be sure and remember: Quaternion angles != euler angles. It would be better to record the Quaternion.eulerAngles into a Vector3 and then set the values to zero:

 //Convert rotation into readable angles.
 Vector3 eulerRotation = transform.rotation.eulerAngles;
 
 //Set non essential angles to 0.
 eulerRotation.x = 0;
 eulerRotation.z = 0;
 
 //Reset the transform rotation.
 transform.rotation = Quaternion.Euler(eulerRotation);

x4000 Sprite101 · Jun 01, 2016 at 01:00 PM 0

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Nice -- ultimately that is what I wound up doing in order to get around the issue. I figured that something as generalized as zero would have the same meaning in both quaternion and euler angles. But it seems like in some cases... not?

Answer 4

We can also read from the constraints bits if they change in runtime (can be done like this) or if we want our artist/rigger/animator to be able to change the constraints from the editor:

 byte bits = (byte)rigidbody.constraints;
 if ((bits & (1 << 1)) != 0)
     Debug.Log("x position frozen");
 if ((bits & (1 << 2)) != 0)
     Debug.Log("y position frozen");
 if ((bits & (1 << 3)) != 0)
     Debug.Log("z position frozen");
 if ((bits & (1 << 4)) != 0)
     Debug.Log("x rotation frozen");
 if ((bits & (1 << 5)) != 0)
     Debug.Log("y rotation frozen");
 if ((bits & (1 << 6)) != 0)
     Debug.Log("z rotation frozen");

We can use this information to make a hacky override to our objects localRotation:

 // save startRotation during Start() or something
 
 byte bits = (byte)rigidbody.constraints;
 Quaternion frozenRotation= new Quaternion(
     (bits & (1 << 4)) != 0 ? startRotation.x : transform.localRotation.x,
     (bits & (1 << 5)) != 0 ? startRotation.y : transform.localRotation.y,
     (bits & (1 << 6)) != 0 ? startRotation.z : transform.localRotation.z,
     transform.localRotation.w
 );
 transform.localRotation = frozenRotation;

Note: setting transform.localRotation.w as the w component will be slightly off, since that holds the total rotation magnitude before we clamped the rotation back to the start rotation... I think.

Answer 5

Answer by ZenMicro · Mar 06, 2016 at 02:44 PM

I am not 100% sure, but for me i changed the collider to a cube and the issue seems to be resolved, Has anyone tried this? even just for the lowest part collider of whatever your model is?

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stfm · May 13, 2017 at 08:47 PM 1

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I have a cube collider, but it does not work.

Unity 5.0 Physics Freeze rotation not working

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