Resolved Initialize LayerMask method doesn't work

Hello everyone, I've written an extension class to help me initialize LayerMasks on startup. The problem is, when I do this, it's perfectly fine :

Code (CSharp):

1.  LayerMask whatIsGround;
2.   void Start()
3.     {
4.  
5.         if (whatIsGround.value == 0)
6.         {
7.             whatIsGround = 1 << LayerMask.GetMask("Ground", "GravitySurface");
8.             whatIsGround = ~whatIsGround;
9.         }
10.  
11.  
12.     }

But when I do this, the New() method doesn't work ?

Code (CSharp):

1. LayerMask whatIsGround;
2.   void Start()
3.     {
4.         if (whatIsGround.Null()) whatIsGround.New("Ground", "GravitySurface");
5.  
6.      }
7.  
8.  
9. namespace Utilities
10. {
11.     public static class LayerMasks
12.     {
13.        
14.         public static bool Null(this LayerMask mask)
15.         {
16.             return mask.value == 0;
17.         }
18.  
19.  
20.         public static LayerMask New(this LayerMask mask, params string[] layers)
21.         {
22.             mask = 1 << LayerMask.GetMask(layers);
23.             mask = ~mask;
24.             return mask;
25.         }
26.     }

I've called the namespace with the using keyword, the compiler doesn't throw any errors and the Null() method is correctly checked. So why does my LayerMask not register these new Layers and stays with the default "Nothing" layer ?

 

LayerMask

is a value type and gets copied instead of referenced. So your

New

method gets a copy of the mask value, changes it, returns a changed copy, but then your code in

Start

discards the returned value. The original

whatIsGround

field is never changed.

You need to assign the return value to copy the changes back to the field:

Code (CSharp):

1. if (whatIsGround.Null()) whatIsGround = whatIsGround.New("Ground", "GravitySurface");

 

Thank you, I was scratching my head for two hours now. I thought the "this" keyword allowed me to do just that but apparently it's just a shortcut, so I'll remove it.

Edit : Just checked my values in the inspector, it turns out that this operation returned a LayerMask with all layers active except "Nothing", "Everything" and "Default", instead of just returning the layers I passed as parameters. What could that come from?

 

Ok, nevermind, I found a workaroung for creating a new Layermask :

Code (CSharp):

1.  
2.         public static LayerMask New(params string[] layers)
3.         {
4.             LayerMask mask = new LayerMask();
5.             mask = mask.Add(layers);
6.             return mask;
7.         }
8.  
9.  
10.         public static LayerMask Add(this LayerMask mask, params string[] layers)
11.         {
12.             for (int i = 0; i < layers.Length; i++)
13.             {
14.                 if (!mask.Contains(LayerMask.NameToLayer(layers[i])))
15.                     mask |= 1 << LayerMask.NameToLayer(layers[i]);
16.             }
17.             return mask;
18.         }
19.  
20.