Having trouble with simple 2D missile homing script

Scripting
1

I think my brain isn’t working this morning, something in my math is wrong. The missile either doesn’t rotate at all, or quickly oscillates between two angles.

Here is my script:

function GetNewRotationAngle(){

    var targetAngle : float = Angle2D(Vector2(transform.position.x, transform.position.y), Vector2(target.x, target.y));
      
    var angleDiff : float = transform.eulerAngles.x - targetAngle;
  
      
    if(angleDiff >= 180f){
  
        angleDiff -= 360f;
  
    }else{
        if(angleDiff <= -180f){
      
            angleDiff += 360f;
        }
    }
  
    var turnSpeed : float = rotationDegreesPerSecond*Time.deltaTime;
    var result : float;
  
  
    if(turnSpeed<Mathf.Abs(angleDiff)){
      
        result = transform.eulerAngles.x + (turnSpeed * angleDiff);
  
    }else{
        result = targetAngle;
    }  
  
    angleDebug = angleDiff;
      
    return result;
}

function Angle2D(current : Vector2, target : Vector2){
  
     return Mathf.Atan2(target.y-current.y, target.x-current.x) * Mathf.Rad2Deg;
}

Note that I’m doing this in the 3D engine. Thanks for the help guys

EDIT:

thanks to bigmisterb for the solution. here is the code i ended up with that worked for me. note that i’m doing this on rigidbodies

rotation:

function GetNewRotationAngle(){
   
    var targetDir : Vector3 = target - rigidbody.position;
    targetDir.z = 0f;
    var newRotation = Quaternion.LookRotation(targetDir, Vector3.forward);
    var deltaRotation : Quaternion = Quaternion.RotateTowards(rigidbody.rotation, newRotation, rotationDegreesPerSecond*Time.deltaTime);
   
    rigidbody.MoveRotation(deltaRotation);
}

movement: (in order to get it to work on one axis, i had to clamp the z position of the rigidbody)

function UpdateMovement(){
    var movement : Vector3 = rigidbody.position + transform.forward * (moveSpeed * Time.deltaTime);
    movement.z = 0f;
    rigidbody.MovePosition(movement);
}
2

I almost never use angles. Quaternions are very easy to manipulate without all the extra thought.

function DoRotation(){
	var rotationDegreesPerSecond = 10;
	Quaternion rotation = transform.rotation;
	transform.LookAt(target);
	// if you have problems with the up direction....
	// transform.LookAt(target, Vector3.back);
	
	transform.rotation = Quaternion.RotateTowards(rotation, transform.rotation, rotationDegreesPerSecond * Time.deltaTime);
}
3

I’ll give this a shot. I don’t understand quaternions on a mathematical level, which is why I’ve tried to shy away from them in the past

quick edit: won’t transform.look at make it rotate instantly instead of over time?

4

Works great! one problem though is that I need to have them rotate on only one axis. how can i do that with quaternions?

5

using an up direction will be the key to doing it on one axis.

So if you are using 2d, then forward and backward (z) should be correct, if it is not simply replace it with transform.up.

transform.LookAt(target, transform.up);

ok. Transform.LookAt makes it look instantly at the object, yes, however, keeping the other rotation back means that you can use Quaternion.RotateTowards with the original rotation. So RotateTowards will do all the actual math work, and you don’t have to.