Way to convert player input to angle/rotation?

Unity Engine
1

Hi there, I will try to be as specific as possible.

I am developing a 2D sidescrolling game with sprites (2DToolkit), and I am stucked with this issue. First of all I need to make clear one thing: in order to change the sprite’s transform without affecting the controls, I am storing it under a different game object which is child to the player main object.

Now, when I have my character swimming, I can make him dive so the player can control him with fully 360º freedom. I am trying to do something as in Rayman Origins, I want the sprite to rotate towards the player direction: when my character is diving down, I want the sprite to rotate and face the bottom of the screen, when he turns left I want the sprite to rotate and face left… and so on.

Is there any way to convert player input to an angle or rotation value? Or a way to compare both things? For now, what I have is this:

    var playerAngle : float = 0.0;
    
    for (var child : Transform in transform)
    {
    	playerAngle += Input.GetAxis("Horizontal") * rotationSpeed * Time.deltaTime;
       	
    	//When Input		 	
    	child.transform.Rotate(Vector3(0, 0, 1) * playerAngle);
    					
    }

But that is a very, very simple and rough code. I want the rotation of the sprite to stop when it matches the Player direction. Is there any quick way to do this or must I try it differently?

By the way, Input comes via WASD.

Thanks for your time.

2

One way to convert player input to Angle would be to calculate the Angle between the input vector and the forward direction for instance.

This is a crude example and hopefully enough to point you in the right direction.

 void Update()
    {
       Vector3 moveVector = Vector3.zero;

        moveVector.x = Input.GetAxis("Horizontal");
        moveVector.y = Input.GetAxis("Vertical");

        float angle = Vector3.Angle(moveVector, Vector3.right);      
        Vector3 cross = Vector3.Cross(moveVector, Vector3.right).normalized;
       
        Debug.DrawLine(Vector3.zero, moveVector, Color.green);
        Debug.DrawLine(Vector3.zero, cross, Color.red);
        Debug.Log("Vector3 Angle:" + angle +  "   Cross (Z):" + cross.z + "   Angle:" + angle * -cross.z);
    }

debug.logs and debug.draw are there to help visualize those vectors.

Because Angle is 90 when up or down as opposed to 90 up and -90 down, I take the cross product which returns a vector that is perpendicular (z direction) to the input and right vector. The Z component of that vector (positive or negative) allows you to know if we are up or down.

Instead of normalizing this cross product, I could have instead used Mathf.sign to just get the positive or negative sign of the cross product which would have been more efficient then normalizing a vector.

Anyway, I hope this helps.

3

@Stephan_B Hey! I kind of made it work, thank you very much. In case you’re interested on it, here’s my current code:

//======================Diving===========================

if(diving)
	{
		gravity = 0.0;
		
		moveDirection = Vector3(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical"), 0);
		moveDirection = transform.TransformDirection(moveDirection);
		moveDirection *= speed;
		
		if (Input.GetKey(KeyCode.RightArrow)  !facingRight)
		{
			script = gameObject.GetComponentInChildren(tk2dSprite);
			script.FlipX();
			facingRight = true;
		}
		
		else if (Input.GetKey(KeyCode.LeftArrow)  facingRight)
		{
			script = gameObject.GetComponentInChildren(tk2dSprite);
			script.FlipX();
			facingRight = false;
		}
		
		else if (Input.GetKey(KeyCode.DownArrow))
		{
			if(!facingRight)
			{
			script = gameObject.GetComponentInChildren(tk2dSprite);
			script.FlipX();
			script.FlipY();
			upsideDown = true;
			facingRight = true;
			}
		}
		else if (Input.GetKey(KeyCode.UpArrow))
		{
			if(!facingRight)
			{
			script = gameObject.GetComponentInChildren(tk2dSprite);
			script.FlipX();
			script.FlipY();
			upsideDown = true;
			facingRight = true;
			}
		}
		
		if(Input.GetKey(KeyCode.LeftArrow)  upsideDown)
		{
			script.FlipY();
			upsideDown = false;
		}
		else if(Input.GetKey(KeyCode.RightArrow)  upsideDown)
		{
			script.FlipY();
			upsideDown = false;
		}
		
		if (Input.GetKey(KeyCode.DownArrow) || Input.GetKey(KeyCode.UpArrow) || Input.GetKey(KeyCode.RightArrow) || Input.GetKey(KeyCode.LeftArrow))
		{
    			for (var child : Transform in transform)
				{
					var moveVector = Vector3.zero;

        			moveVector.x = Input.GetAxis("Horizontal");

       				moveVector.y = Input.GetAxis("Vertical");
       				
        			if(Input.GetKey(KeyCode.LeftArrow))
        			{
        				moveVector.x = -Input.GetAxis("Horizontal");
        				moveVector.y = -Input.GetAxis("Vertical");
        			}

        			var angle = Vector3.Angle(moveVector, Vector3.right);      

        			var cross = Vector3.Cross(moveVector, Vector3.right).normalized;
        			
        			child.transform.rotation = Quaternion.Euler(Vector3(0, 0, angle * -cross.z));
				}
		}	
	}

Now I just have some weird issues to solve involving the sprite (it makes odd Flips sometimes, but I think I just messed it up with excessive “facingRight” and “upsideDown” coding).

Anyway, the rotation of the sprite works fine. Thx!