Mouse Aiming Causing Rotation Jitter

[PartyMix]

When our game’s ships move around, mouse aiming causes them to shake around very noticeably. The body being aimed is moved kinematically. I think we’ve narrowed it down to this block of mouse tracking code.

Demonstration of the glitch

You can see around 0:35 where I disable the mouse tracking code momentarily, the ship stops shaking.

		public static Quaternion RotateToMouse(this Ship ship, Transform transform, float ShipRotateSpeed)
		{
			// Generate a plane that intersects the transform's position with an upwards normal.
	    	Plane playerPlane = new Plane(Vector3.up, Vector3.zero);
					
	    	// Generate a ray from the cursor position
	    	Ray ray = Camera.main.ScreenPointToRay (Input.mousePosition);
	 
	    	// Determine the point where the cursor ray intersects the plane.
	    	// This will be the point that the object must look towards to be looking at the mouse.
	    	// Raycasting to a Plane object only gives us a distance, so we'll have to take the distance,
	    	//   then find the point along that ray that meets that distance.  This will be the point
	    	//   to look at.
	    	float hitdist = 0.0f;
	    	// If the ray is parallel to the plane, Raycast will return false.
	    	if (playerPlane.Raycast (ray, out hitdist)) 
			{
	        	// Get the point along the ray that hits the calculated distance.
	        	Vector3 targetPoint = ray.GetPoint(hitdist);
				
	        	// Determine the target rotation.  This is the rotation if the transform looks at the target point.
	        	Quaternion targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
				
	        	//rotate towards the target point.
	        	transform.rotation = Quaternion.RotateTowards(transform.rotation, targetRotation, ShipRotateSpeed);
				transform.eulerAngles = new Vector3(0, transform.eulerAngles.y, 0);
			}
			return transform.rotation;
		}

The issue isn’t the fact that the plane is stationary, and it can’t be solved by rounding. We’ve got no idea what to do, and it’s driving us bananas. Help!

[PartyMix]

My partner solved it! It turns out that because the camera moves with the ship, there’s all sorts of factors that come into play when all of our physics, movement, and camera tracking scripts are shoving the ship around. He fixed it by making a new stationary camera at 0 0 0, then detecting the ship’s desired rotation using that instead of the ship-tracking camera.

[randomuser]

Have you tried this with multiple mice? I would print to mouse values on the console to see the amount of the mouse jitter. If it is pretty small, I would try to implement the equivalent of a dead-zone for the mouse. Make it so in order for the mouse to have any effect it has to move more than say 5 pixels in 5 loops of Update(). The code would be slightly complicated but would probably solve the problem.

[Prosto_Lyubo]

There is simpler solution.That jittering happens because GUI is updated more frequently than the Update or LateUpdate. Just move the code related to raycasting from moving camera through cursor position into the OnGUI() function instead of Update() or LateUpdate(). Everything runs smoothly. Just remember that it may be called more than one time per frame so do there only what is necessary.