Unity find objects within range of two angles and with a max length (pie slice)

Question

I've been programming an ability for a Hack n Slash which needs to check Units within a pie slice (or inbetween two angles with max length). But I'm stuck on how to check whether an unit is within the arc.

Scenario (Not enough, rep for an image sorry im new)

I currently use Physics2D.OverlapSphere() to get all of the objects within the maximum range. I then loop through all of the found objects to see whether they are within the two angles I specify. Yet this has janky results, probably because angles don't like negative values and value above 360.

How could I make this work or is there a better way to do this? I probably need to change the way I check whether the angle is within the bounds.

Thanks in advance guys! I might respond with some delay as I won't be at my laptop for a couple hours.

Here is the code snippet:

public static List<EntityBase> GetEntitiesInArc(Vector2 startPosition, float angle, float angularWidth, float radius)
{
    var colliders = Physics2D.OverlapCircleAll(startPosition, radius, 1 << LayerMask.NameToLayer("Entity"));
    var targetList = new List<EntityBase>();

    var left = angle - angularWidth / 2f;
    var right = angle + angularWidth / 2f;

    foreach (var possibleTarget in colliders)
    {
        if (possibleTarget.GetComponent<EntityBase>())
        {
            var possibleTargetAngle = Vector2.Angle(startPosition, possibleTarget.transform.position);
            if (possibleTargetAngle >= left && possibleTargetAngle <= right)
            {
                targetList.Add(possibleTarget.GetComponent<EntityBase>());
            }
        }
    }

    return targetList;
}

Possible duplicate of [Finding Signed Angle Between Vectors](https://stackoverflow.com/questions/2150050/finding-signed-angle-between-vectors) — Draco18s no longer trusts SE, May 21 '18 at 02:51

score 1 · Accepted Answer · answered May 21 '18 at 03:17

Vector2.Angle(startPosition, possibleTarget.transform.position);

This is wrong. Imagine a line from the scene origin (0,0) to startPosition and a line to the transform.position. Vector2.Angle is giving you the angle between those two lines, which is not what you want to measure.

What you actually want is to give GetEntitiesInArc a forward vector then get the vector from the origin to the target position (var directionToTarget = startPosition - possibleTarget.transform.position) and measure Vector2.Angle(forward, directionToTarget).

Thank you, this helped me out and it was a short and clean anwser! The example that you gave made it easy to understand! — TwinGhosts, May 21 '18 at 13:34

Unity find objects within range of two angles and with a max length (pie slice)

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