Slowing down mouse movement in Unity

Question

I'm using the game to control electronics. I use the following code to determine the location of an object (the location is used to perform calculations that are sent to the electronics)

int centerX = Screen.width/2;
int centerY = Screen.height/2;
Vector3 centerVec = new Vector3(centerX, centerY);
Vector3 diffFromCenter = Input.mousePosition - centerVec;
Ray ray = Camera.main.ScreenPointToRay(centerVec + 0.5F*diffFromCenter);

This is used (along with a raycast to determine the appropriate y value) to determine the location of the object.

The reason I use 0.5*diffFromCenter is because of the sensitivity of the movement (as seen in the reaction of the electronics)

The problem with this approach is that it when the (real) cursor reaches the edge of the screen and can't move further, the in-game object won't be able reach the edge of the game window.

The only idea I could come up with to solve this problem is to use code to change settings on the speed of the mouse's movement.

I can't come up with a better solution (and this one would require that I also detect when the cursor leaves the game window to restore the mouse movement speed, because we'll be running experiments and someone might need to tweak things during the experiment...)

Answer 1

1. Make the regular hardware mouse cursor disappear with Cursor.visible = false; in the Start method of some script.
2. Create a new game object called "Mouse Cursor". I recommend using an image on a screen-space canvas for this purpose, but in a 2d game you could use a sprite in world-space as well. Give it a pointy-looking sprite asset which goes well with the aesthetics of your game UI.
3. Create a script on it which uses Input.GetAxis("Vertical") and Input.GetAxis("Horizontal") to measure the vertical and horizontal mouse movement since the last update. Multiply that value with Time.deltaTime and your desired speed multiplier, and change the position of the mouse cursor object accordingly.
4. You might notice that it is now possible for your new custom mouse cursor to move outside of the screen. So you need to make sure to keep it within the screen boundary. You can do that with:

    transform.position = new Vector3(
         Mathf.clamp(transform.position.x, 0f, Screen.width),
         Mathf.clamp(transform.position.y, 0f, Screen.height),
         0f
    );

5. Now you might want to know how to find out if and which collider the mouse pointer is pointing at.
   • For a 3D game with regular (3D) colliders and a perspecitve camera, feed the cursor coordinates to Camera.ScreenPointToRay and then feed the resulting ray into Physics.Raycast(ray, out hitInfo).
   • For a 2D game with 2d colliders and an orthographic camera, feed the cursor coordinates to Camera.ScreenToWorldPoint and then use Physics2D.OverlapPoint.