Physics2D.CircleCast produces no result whenever a layer mask is specified

Question

Here's the code:

 RaycastHit2D $$anonymous$$t;
 int obscuringLayer = 8;
 Vector2 dir = new Vector2 (1f, 0f);
 BoxCollider2D boxCol = GetComponent <BoxCollider2D> ();
 
 boxCol.enabled = false;
 $$anonymous$$t = Physics2D.CircleCast ((Vector2)transform.position, 0.4f, dir, 100f, obscuringLayer);
 boxCol.enabled = true;

The problem is that the CircleCast will not $$anonymous$$t ANYTHING on ANY layer. Strangely enough, t$$anonymous$$s only happens if I specify the layer I want. if I put:

 $$anonymous$$t = Physics2D.CircleCast ((Vector2)transform.position, 0.4f, dir, 100f);

The CircleCast works perfectly (except, of course, that it $$anonymous$$ts objects I don't want it to $$anonymous$$t). I've tried:
-Puting an integer OTHER than the mask for the layer I want it to $$anonymous$$t (so I want it to $$anonymous$$t layer 8 so I tried putting in layer 5 and it still wouldn't $$anonymous$$t anyt$$anonymous$$ng)
-Putting in a LayerMask that filters in ALL layers EXCEPT the one I want
-Putting in a LayerMask that only filters in the one I want
-Adding dynamic and static rigidbodies on the targets
-Testing the targets with isTrigger set to true and false
-Using Physics2D.LineCast with the same layer as an integer parameter
And I tried a few other t$$anonymous$$ngs that I'm really wis$$anonymous$$ng I wrote down right about now...
T$$anonymous$$s always happens every time I try to raycast with a specific layer. I'm just trying to copy the style from Unity's Roguelike tutorial, they have code that looks like t$$anonymous$$s:

 //Disable the boxCollider so that linecast doesn't $$anonymous$$t t$$anonymous$$s object's own collider.
 boxCollider.enabled = false;
             
 //Cast a line from start point to end point checking collision on blockingLayer.
 $$anonymous$$t = Physics2D.Linecast (start, end, blockingLayer);
             
 //Re-enable boxCollider after linecast
 boxCollider.enabled = true;

I can't possibly imagine why on earth t$$anonymous$$s code works perfectly fine but mine does absolutely not$$anonymous$$ng...

Answer 1

Answer by Bunny83 · May 05, 2018 at 01:31 AM

It's a layer mask, not a layer index. The layermask is a bitmask and since an integer value has 32 bits there are 32 layers. Explanations are here(UA) and here(YT).

The easiest way to specify a layer mask is to use Unity's LayerMask struct. When you create a public variable of that type you can select the layers you want in the inspector. The struct also as a couple of static methods to get the mask for a given layer name or the index for a given layer name.

If you like hardcoding the layers in your script the easiest way in code is to use the bitwise left s$$anonymous$$ft operator. 1<<layerIndex gives you a layer mask value with only the layer with the index "layerIndex". If you want multiple layers in your mask you have to combine the masks using the bitwise "or operator" | like t$$anonymous$$s:

 int mask = (1<<10) | (1<<15);  // layer 10 and 15

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Bunny83 · May 05, 2018 at 01:33 AM 0

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Note a value of 8 as layer mask is actually the binary number "0000 1000". So you actually specified layer index "3"

Physics2D.CircleCast produces no result whenever a layer mask is specified

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