How to reference the right object in Unity

Question

So, I'm developing this small 2D project where I have a sphere that detects if objects get close to it from three different directions.

I have successfully found a way to detect if an object touches my line if the object is referenced to a certain LayerMask, in this case the walls.

So, basically I'm doing this:

var layerMask = 1 << 10; //wall layer
float left = 0f, middle = 0f, right = 0f;

Debug.DrawLine (leftStart.position, leftEnd.position, Color.green);
Debug.DrawLine (middleStart.position, middleEnd.position, Color.green);
Debug.DrawLine (rightStart.position, rightEnd.position, Color.green);

leftSpot = Physics2D.Linecast(leftStart.position, leftEnd.position, layerMask);
middleSpot = Physics2D.Linecast(middleStart.position, middleEnd.position, layerMask);
rightSpot = Physics2D.Linecast(rightStart.position, rightEnd.position, layerMask);

Now, what I would like to do is reference the right wall (Horizontal or vertical) and calculate the distance between the wall and my sphere with:

Vector2.Distance(transform.position, wall1.position);

How can I get the reference to the correct wall to do this?

Thank you

Answer 1

You should be getting a RaycastHit2D object back from your test. You can access the hit info from that to get the distance and other information about the object you hit. Something like the following:

RaycastHit2D leftHitInfo = Physics2D.Linecast(leftStart.position,
           leftEnd.position, layerMask);

if(leftHitInfo.collider != null) {
   Debug.Log("Left hit! Distance: " + leftHitInfo.distance.ToString());
}

If you're performing this test regularly, I suggest you use the non-alloc version of this method:

int maxReturnedIntersections = 5;
RaycastHit2D[] hitResults = new RaycastHit2D[maxReturnedIntersections];

int hitCount = Physics2D.LinecastNonAlloc(leftStart.position, leftEnd.position, hitResults, layerMask);

if(hitCount > 0) {
    Debug.Log("Left hit! First distance: " + hitResults[0].distance.ToString());
}

Ideally, you'd create the array of hit results outside of your method so you're not creating a new one over and over.