(Yet Another) Rotation Issue

Questions & Answers
1

I’m trying to create an MMO-style camera, i.e. a camera that rotates around an object. When the player holds down the left-mouse, the camera rotates around the object. The right-mouse button does the same thing excepting that the object matches the y-axis rotation of the camera. The camera seems to be rotating properly, but when between certain values, the player object’s rotation (not the camera[I think]) seems to go awry. I’m not sure what the exact numbers are (the seem to very) but it’s always when the camera is facing the same general direction, that is, roughly between the negative x and z axis in world-space.

Here is my code:

#pragma strict
var objectToFollow : GameObject;
var cameraObject : GameObject;
var startingDistance = 0.0;
var startingHeight = 0.0;
var sensitivity = 10;
var playerSpeed = 0.0;
private var distance : float;
private var height : float;
private var rotationVector = Vector3.back;


function Start () {
	distance = startingDistance;
	height = startingHeight;
	cameraObject.transform.position = objectToFollow.transform.position + 
		(Quaternion.Euler(0,objectToFollow.transform.eulerAngles.y,0) * Vector3.back * distance);
}

function Update () {
	//Mouse routines BEGIN
	distance = Mathf.Clamp(distance + Input.GetAxis("Mouse ScrollWheel") * Time.deltaTime * 200 , 0, 20);
	if(Input.GetMouseButton(1))
	{
		objectToFollow.transform.rotation.y = cameraObject.transform.rotation.y;
	}
	if(Input.GetMouseButton(0) || Input.GetMouseButton(1))
	{
		if(Input.GetAxis("Mouse X")!=0)
		{
			rotationVector = Quaternion.Euler(0,Input.GetAxis("Mouse X") * sensitivity,0) * rotationVector;
			
		}
		if(Input.GetAxis("Mouse Y")!=0)
		{
			rotationVector = Quaternion.AngleAxis(-Input.GetAxis("Mouse Y") * sensitivity, 
				cameraObject.transform.right) * rotationVector;
		}
	}
	var hit : RaycastHit;
	if(Physics.Raycast(objectToFollow.transform.position,rotationVector,hit,distance))
	{
		cameraObject.transform.position = objectToFollow.transform.position + (rotationVector.normalized * hit.distance);
	} else {
		cameraObject.transform.position = objectToFollow.transform.position + (rotationVector.normalized * distance);
	}
	
	cameraObject.transform.LookAt(objectToFollow.transform);
	
	//Mouse routines END
	
	//Keyboard routines BEGIN
	
	if(Input.GetAxis("Vertical"))
	{
		objectToFollow.transform.Translate(Vector3.forward * Time.deltaTime * playerSpeed * Input.GetAxis("Vertical"));
	}
	if(Input.GetAxis("Horizontal"))
	{
		objectToFollow.transform.Translate(Vector3.right * Time.deltaTime * playerSpeed * Input.GetAxis("Horizontal"));
	}
	//Keyboard routines END
}
2

This line is wrong:

  objectToFollow.transform.rotation.y = cameraObject.transform.rotation.y;

transform.rotation is a quaternion, not those nice angles we see in the Inspector (they are actually the property transform.localEulerAngles). Copying the Y component from one quaternion to another makes no sense, and weird things will happen at certain angles.

The solution depends on exactly what you want the objectToFollow to do. If objectToFollow must rotate about the world Y axis, things are easier: get the camera’s forward vector, zero its Y component and define the object rotation with LookRotation:

  var dir = cameraObject.transform.forward; // get the camera direction
  dir.y = 0; // consider only the horizontal part
  // turn object in this direction:
  objectToFollow.transform.rotation = Quaternion.LookRotation(dir);
3

im wondering about this line of code right here

 rotationVector = Quaternion.AngleAxis(-Input.GetAxis("Mouse Y") * sensitivity, 
  cameraObject.transform.right) * rotationVector;

it’s multiplying by the old rotation vector. But i’m thinking it might be that rotationVector sometimes equals 0 in which case it multiplies by zero and later in this line

cameraObject.transform.position = objectToFollow.transform.position + (rotationVector.normalized * hit.distance);
} else {
cameraObject.transform.position = objectToFollow.transform.position + (rotationVector.normalized * distance);

these get multiplied by zero and so along a zero wierd stuff might happen.

Try changing it to

if(Input.GetAxis(“Mouse Y”)!=0 && rotationVector != 0)

and tell me if that does anything.