Question Rotate Rigidbody with AddTorque towards a specific location.

I have a main camera that rotates around an object (which I already move with AddForce).
Using AddTorque, I would like the object to rotate its Y axis of rotation in the direction in which the camera's Y axis of rotation points so as to simulate the rotation of a person turning around.
To do this I thought of using a force that gave me 0 when the Y axes of the two objects are the same, but I tried and the rigidbody covers only one part of the rotation of the camera while the other part is as if it not is detected.

Code (CSharp):

1. var currentR = rb.rotation.y;
2. var targetR = Camera.main.transform.rotation.y;
3. rb.AddTorque(transform.up * 1000f * (targetR - currentR));

rotation my object desired rotation

 

What do you mean with "one part" of the rotation? If you mean only 1 dimension, that's because in your code you only compare the y coordinate. You should do it for all rotations.

Take a look at this: https://answers.unity.com/questions/199055/addtorque-to-rotate-rigidbody-to-look-at-a-point.html

 

I don't mean just one dimension (the Y axes are used only as a unit of measure in the script). I mean that rotation only works when I rotate the camera in a certain range, if I rotate it more the object no longer rotates.
You can also see from the video that I posted in "rotation my object" as with this script objects do not follow the whole rotation of the camera.


I had already heard of the PID controller but I didn't quite understand how to use it, if someone describes me how to apply it for the desired result it would help me a lot.

 

Here we go again
In your video you can see that after a certain point, the character suddenly rotates the other way. I assume this is because the “y” rotation wraps. This means it only has values between 0 and 359.999 degrees.. or -180 and 180 or something else. That’s one of the reasons that working with Euler angles is not a good idea in this case.

Stick with vector math:

Code (CSharp):

1. Vector3 camForward = Camera.main.transform.forward;
2. Vector3 rbForward = rb.transform.forward;
3.  
4. Vector3 torque = Vector3.Cross(camForward, rbForward);
5. rb.AddTorque(torque);
6.  

Maybe you have to swap camForward and rbForward in the Cross() function if the rigidbody turns the wrong way.

If you wish to only rotate around the world y-Axis, you have to project the torque vector onto this axis https://docs.unity3d.com/ScriptReference/Vector3.Project.html

Code (CSharp):

1. Vector3 torqueY = Vector3.Project(torque, Vector3.up);

Be aware that this code will overshoot the desired orientation. You can add rotational damping, either in the rigidbodies settings or yourself in code like this

Code (CSharp):

1. rb.AddTorque(-rb.angularVelocity);

Concerning PID:
We already implemented two of the letters with the code that I gave you:
Proportional: The difference between the state and the target of the controlled system, also called error, is added proportionally (P) to the input of the system.

Differential: The derivative of the error is also added to the input of the system (in our case just the angular velocity)

Integral: The error is summed up over time and also added to the systems input. (We didn’t do this and we also don’t need to in this case)

Feedback control is a vast topic (that I happened to have studied) that is somewhat intimidating but for cases like “follow control” really understandable once you get the hang of it.

 

Very thanks for the reply
Vector3.cross has given me good results with the inverted parts. I honestly knew him but I thought that it gave a vector halfway between vectors A and B, and therefore using it the object would have stopped halfway, but it is not so and instead it works. The flaw is that if I use it as it is, the X and Z axes also rotate, so I have to freeze these.

Vector3.Project together with the damping, it work, but the damping does not do its duty and the object often stops further ahead