How to get all layers included in a LayerMask?

Question

I want to use LayerMasks in my script, but not for raycasting. I can make a public LayerMask variable which will appear in the inspector, but I'm not sure how to get the layer information out of the LayerMask.

In the end, I want something like this:

 // whether the layer was selected in the inspector or not
 bool[] layersArray = myLayerMask.GetLayers(); 
 
 for(int i = 0; i < layersArray.length; i++) {
     // do something with the layers
 }

Answer 1

Can't test right know, but try that:

 [SerializeField]
 private LayerMask layerMask;

 private bool[] hasLayers = new bool[32];

 private void CheckMasks()
 {
     for (int i = 0; i < 32; i++)
     {
         if (layerMask == (layerMask | (1 << i)))
         {
             hasLayers [i] = true;
         }
     }
 }

EDIT: Already tested and working!

EDIT2: Here is two LayerMask extensions to help! Just create a c# script "LayerMaskExtensions" and copy paste the code.

 public static class LayerMaskExtensions
 {
     public static bool HasLayer(this LayerMask layerMask, int layer)
     {
         if (layerMask == (layerMask | (1 << layer)))
         {
             return true;
         }
 
         return false;
     }
 
     public static bool[] HasLayers(this LayerMask layerMask)
     {
         var hasLayers = new bool[32];
 
         for (int i = 0; i < 32; i++)
         {
             if (layerMask == (layerMask | (1 << i)))
             {
                 hasLayers[i] = true;
             }
         }
 
         return hasLayers;
     }
 }

To use it:

 public LayerMask layerMask;
 public int layer;
 
 void Method()
 {
     bool hasLayer = layerMask.HasLayer(layer);
     bool[] hasLayers = layerMask.HasLayers();
 }

Answer 2

Answer by Bunny83 · Jan 29, 2016 at 02:45 AM

Uhm it's not really clear what you want to do with the layer information. The LayerMask struct can only handle the layers defined in the tag / layer manager. A layermask is simply an uint value which represents a bit mask where each bit of the 32 bit number represent one layer.

So a value of "6" would be: 00000110 in binary. As you can see bit 1 and 2 are set if you start counting at 0.

You can use usual bit operations to check for a specific bit in a bit mask.

 uint bitMask  = 0x00e5; // 0000 0000 1110 0101
 if ((bitMask & (1 << 3)) > 0) // check if bit 3 is set. In this case it is not set. Keep in mind the lowest bit is 0
 bitMask |= 1<<4; // set bit 4 --> 0001 0000
 // bitMask now contains        -> 1111 0101

See the following posts for more information:

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Answer 3

Answer by MrBalin · Nov 05, 2019 at 12:30 AM

if you want to check against all layers, I found this substitute works: Physics.DefaultRaycastLayers

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Answer 4

Answer by sj631 · Sep 01, 2021 at 10:24 AM

 LayerMask originalLayerMask = 2 | 4;
 LayerMask layerMaskToCheck = 2;
 LayerMask combinedLayerMask = originalLayerMask | layerMaskToCheck;
 
 if (combinedLayerMask.value == originalLayerMask.value)
    Debug.Log(layerMaskToCheck.value +" layer Found");

You can try this but keep raycast and collision layers different for performance reasons.

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How to get all layers included in a LayerMask?

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