Rotation follow translation

[mustang4484]

Hi guys

I would like to make an object that rotates on the y axis based on the translation (not rotation) of another object on the x axis.

Something can help me?

[DCordoba]

well after remembering a bit of math, here we go;
Iam not sure if diff get the correct distance, the rest is geometry and the transform.Rotate function:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class BasicTrack : MonoBehaviour {
	public Transform TargetObject; //set it on inspector
	public float Angle = Mathf.PI ;//proportional rotation of the second object, default is the same angular translation at diameter 1, multiply by 2 radius to change angular rotation
	float StartPoint = 0;
	float diff; //reusable variable, distance from current x position to previous

	void Start () {
		StartPoint = TargetObject.position.x;
	}
	// FixedUpdate is use by physics
	void FixedUpdate () {
		//this if really not work with floats, use a aproximate comparision like Mathf.Abs(Mathf.Abs(StartPoint)-Mathf.Abs(TargetObject.x))<0.01f
		if (StartPoint != TargetObject.position.x) {
			//PI*radius*2 is the distance that a wheel do on a single rotation
			diff = TargetObject.position.x-StartPoint;
			transform.Rotate (Vector3.up, (360/Angle)*diff); 
			StartPoint = TargetObject.position.x;
		}
	}
}

of course the script will be attached to the object that rotate, the TargetObject is the object moving along the x.

Edited @mustang4484 eliminating the last Mathf.Absu have a unclamped rotation at two directions, to do inverse clockwise replace transform.Rotate (Vector3.up, (360/Angle)*diff); with transform.Rotate (-Vector3.up, (360/Angle)*diff); (note the minus…)

[mustang4484]

Thank you all, I explained myself badly.
I would like that when my Object P move on the right (B) my arrow turn to (B) with degree proportional to start position-b.

It’s a similar to @DCordoba but with the inverse clockwise if the player go to -x.

Thank you

[Magso]

If you have a variable for the rotation then you can do something like this,

float currentRotation, timesDifference, maxAmount;

void Update(){
    transform.eulerAngles.y = currentRotation;
    other.transform.position.x = currentRotation * timesDifference;
    currentRotation = Mathf.Clamp(currentRotation, -maxAmount, maxAmount)
}

edit: I’ve just noticed A and B are going in opposite directions.

other.transform.position.x = -currentRotation * timesDifference;