Accelerometer movement limit according to screen size

Question

I am using this code:

void Update()
{
    accel = Input.acceleration.x;
    transform.Translate (0, 0, accel);
    transform.position = new Vector3 (Mathf.Clamp (transform.position.x,-6.9f, 6.9f), -4.96f, 18.3f);
}

It makes my gameObject move the way I want it BUT the problem is that when I put the app on my phone, (-6.9) and (6.9) are not the "ends" of my screen. And I cannot figure out how to change those values according to every screen size?

Answer 1

This is going to be a bit of a longer answer, so please bear with me here.

Note that this post is assuming that you are using an orthographic camera - the formula used won't work for perspective cameras.

As far as I can understand your desire is to keep your object inside of the screen boundaries. Screen boundaries in Unity are determined by a combination of camera size and screen size.

float height = Camera.main.orthographicSize * 2;

A camera's orthographic size determines the half of the screen's size in world units. Multiplying this value results in the amount of world units between the top and bottom of the screen.

To get the width from this value, we take the value and multiplying it by the screen's width divided by the screen's height.

float width = height * Screen.width / Screen.height;

Now we have the dimensions of our screen, but we still need to keep the object inside those bounds.

First, we create an instance of the type Bounds, which we will use to determine the maximum and minimum values for the position.

Bounds bounds = new Bounds (Vector3.zero, new Vector3(width, height, 0));

Note that we used Vector3.zero since the center of our bounds instance should be the world's center. This is the center of the area that your object should be able to move inside.

Lastly, we clamp the object's position values, according to our resulting bounds' properties.

Vector3 clampedPosition = transform.position;
clampedPosition.x = Mathf.Clamp(clampedPosition.x, bounds.min.x, bounds.max.x);
transform.position = clampedPosition;

This should ensure that your object will never leave the screen's side boundaries!