Determine CW or CCW rotation when using Quaternion

Questions & Answers
1

Hello! In my game I have the ability to rotate the character 180 degrees by pressing a button. This works fine, except I want to be able to determine in which direction it is rotating.

When I press the button the first time it rotates CW 180 degrees, the next time I press the button it rotates CCW 180 degrees (i.e. back t 0 degrees).

I’m using Quaternion.LookRotation to calculate the target, and Quaternion.RotateTowards for the actual rotation. See source below.

Is it possible to tell it in which direction to rotate? Or is there a better way? Thanks!

void TurnAround()
{
	if (!isTurning && (Input.GetButtonDown("TurnAround") || Input.GetAxisRaw("TurnAround") > 0))
	{
		turnAroundTarget = Quaternion.LookRotation(-transform.forward);
		isTurning = true;
	}
	
	if (isTurning)
	{
		transform.rotation =  Quaternion.RotateTowards(transform.rotation, turnAroundTarget, turnAroundSensivity);

		if (transform.rotation == turnAroundTarget)
		{	
			isTurning = false;
		}
	}
}
2

Hi there :slight_smile:

If you’d like to apply CW/CCW rotation simply, you can use Quaternion.EulerAngles, which is a Vector3 and represents what you see in the Editor for “rotation” on a Transform. If you’d always like to rotate 180 CW for example, you can take this approach. The code can be written in a cleaner way, but it’s easier to read like this:

// Need to acquire the full Vector3 even for rotating < 3 axes - you
// can't individually set the x,y,z members

Vector3 rot = transform.rotation.EulerAngles;

// This is your angle to adjust by. Positive values for CW rotation,
// negative values for CCW.

float angleAdjust = -90.0f;    // 90 degrees CCW

// Apply rotation. Unity allows "infinite" rotation - passing 360
// results in 361, rather than 1 degree. Passing 0 CCW results in -1. This may
// or may not be desirable, but it does allow you to just keep adding positive
// numbers for CW rotation, or adding negative numbers for CCW rotation.

rot.y += angleToAdjust;

// If you want to remove the infinite rotation behaviour, you can do so here.
// For CW rotation, limit is 360.
// For CCW rotation, limit is 0

if (rot.y > 360.0f)
    rot.y -= 360.0f;
if (rot.y < 0.0f)
    rot.y += 360.0f;

// Now you can apply the new rotation back to the transform in one step

transform.rotation.EulerAngles = rot;