CircleCastAll layermask doesn't seem to work...

Questions & Answers
1

Hi there, I have made a script in which my AI character circlecasts around itself to detect food. My script appears to work fine except the layermask doesn’t seem to be doing anything. This is my script so far:

public class FindFood01 : MonoBehaviour {

	float rayRadius = 2;
	Vector2 position2D;

	void FixedUpdate () {
	
		if (GetComponent<AI> ().targetFood == null) {

			RaycastHit2D[] hit;

			position2D = new Vector2 (transform.position.x, transform.position.y);

			hit = Physics2D.CircleCastAll (position2D, rayRadius, position2D, 0f, 9);

			GetComponent<AI> ().targetFood = hit [0].transform.gameObject;

		}
	}
}

And I have an AI script that deals with moving the charactor to the target. That bit works fine. The integer 9 is the layer for the food, and I seem to have put this in the correct place. The results though, are that the character detects everything. I can’t tell if it detects anything preferentially or not, but it appears to detect food, the player or sometimes itself (and moves in a straight line forever trying to chase itself). Any ideas on what I’ve missed here?

To clarify in advance, the AI script does nothing until there is a target, and then moves towards it, so it’s not that. And I’ve checked and tripple checked that food is definately layer 9, and that the layer food is only assigned to the food, everything else is on default layer.

Cheers in advance,

Pete

2

Layermasks in Unity are stored as a bitmask, so you don’t input the layer number into the function, but it’s bit-value. So something like 1 << 9 (a bitshift to the left 9 times). To make this much more easy, I would define a public LayerMask field and use the built-in enum dropdown of the Inspector to pick my layer mask.

LayerMask documentation

3

Hey thanks man! That’s perfect. It hadn’t occured to me that I should actually read about how the layerMasks work, thought they would just be the straight forward layer numbers. To clarify, this is my solution based on your answer:

public class FindFoodSmellClosest : MonoBehaviour {

	float rayRadius;
	Vector2 position2D;

	LayerMask foodMask;


	void Start () {

		foodMask = LayerMask.GetMask ("Food");

		rayRadius = Random.Range (1.0f, 5.0f);
	}

	void FixedUpdate () {
	
		if (GetComponent<AI> ().targetFood == null) {

			RaycastHit2D[] hit;

			position2D = new Vector2 (transform.position.x, transform.position.y);

			hit = Physics2D.CircleCastAll (position2D, rayRadius, position2D, 0f, foodMask);

			if (hit [0] != null) {
				GetComponent<AI> ().targetFood = hit [0].transform.gameObject;
			}
		}
	}

Using the line “foodMask = LayerMask.GetMask (“Food”);” I don’t have to find out what the actual the number is, though I debugged it and it’s 512. This means the number must be 2 ^ (layer number, in this case 9), which admittedly is what you already said with “1 << 9 (a bitshift to the left 9 times)”.

Cheers very much man!

Pete