Help with a field of sight

Questions & Answers
1

Im working on getting one of my objects to ‘see’ another. At the moment I’m just doing a raycast but the problem with this is that it’s a single line. This means that unless another object is touching the line, it wont be seen. I need this object to instead have a field of sight branching out from it, similar to how we see. What would be the best way to do this?

2

Get the angle between the objects. Use Vector3.Angle(seeingThing.transform.position,thingToCheck.transform.posion);

Now see if that angle is within the visual fustrum you want. Say +/-45 degrees.

If so then you can do one or more raycasts between the seeing thing and the thing you are checking to make sure there is nothing blocking.

3

Usually this is done by measuring the angle between the target and the look direction: if it’s less or equal to the viewing angle, the object is potentially visible - you should then check if a raycast can hit the target without hitting something else in between:

var viewAngle: float = 30; // degrees from the center

function CanSeeYou(target: Transform): boolean {
  var dir: Vector3 = target.position - transform.position; // find target direction
  var angle: float = Vector3.Angle(transform.forward, dir); // find angle
  var hit: RaycastHit;
  if (angle <= viewAngle && // if inside viewing angle...
    Physics.Linecast(transform.position, target.position, hit) && 
    hit.transform == target){ // and nothing obscuring it...
      // target is visible
  } else {
      // not visible
  }
}

Call CanSeeYou(target) to check whether it’s visible:

function Update(){
  if (CanSeeYou(enemy)){
    // enemy at sight!
  }
}
4

As a rule of thumb I always try to avoid recursive functions. Those are square root and all kind of trig functions.

So if Vector3.Angle is right, I would think it uses arccos within.
Now using dot you avoid the recursion.

Vector3 direction = player.position - _transform.position;
if (Vector3.Dot(direction.normalized, _transform.forward) > 0 )
{
    // Object is front
}

0 means 180 degrees field of view, increasing the value will reduce the field, decreasing until -1 will give eagle eye.

All of those computations are simple arithmetic so pretty fast nowadays.