How do I use layermasks?

Question

Layermasks took me a while to figure out and get working correctly, and I've seen a few people asking about them on the forums, so I thought I'd add a little something to help anyone who may be struggling with them.

The question is: How do I use/create layermasks to use with, e.g., Physics.Raycast or other Physics functions? For those who don't know: a layermask allows you to specify certain layers to exclude/include in certain physics functions.

Answer 1

Answer by Bryan-Legend · Apr 15, 2016 at 09:12 PM

Make sure you're not passing in the layer mask in the distance argument position.

Do This

     if (Physics.Raycast(transform.position, transform.forward, out hit, Mathf.Infinity, SelectionLOSCheckMask))

NOT THIS

     if (Physics.Raycast(transform.position, transform.forward, out hit, SelectionLOSCheckMask))

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Answer 2

Answer by castor · Sep 20, 2016 at 04:21 PM

Honestly, after trying all these methods, I find the easiest to use 'GetMask' command:

You set your variable at the start:

     int maskMouseRaycastDefault;

and then in the Awake function, define the names that create that mask. No need for bit shifting, or memorizing what number is what.

 void Awake(){
         maskMouseRaycastDefault = LayerMask.GetMask("Default", "Collision", "DynamicObjs");
 }

The biggest advantage, and the reason why I stopped using the bit shift method, is that you can very clearly read what your layerMask is composed of, and if for some reason you later need to change your layer order, as long as you preserve the names it still works.

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Owen-Reynolds · Sep 20, 2016 at 05:25 PM 1

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Unity didn't have an official Layermask type when this Q was asked, so you had to learn a little about bit-shifting. So the Q is now partly obsolete.

As it is now, bit-shifting is better if you know it. You can pre-define enemyLayer=1<<9 and so forth, then write enemyLayer | fishLayer. Shorter, Intellisense works on it and it runs faster. The layer$$anonymous$$ask class is a front-end if you don't have a program$$anonymous$$g background; which means if you haven't already used bit-operations before, don't waste your time learning them -- use the Layer$$anonymous$$ask class.

Answer 3

Answer by Adam-Sowinski · Nov 10, 2016 at 01:47 PM

The easiest way of getting the masks is like this:

 var layerNames = new string[] { "YourLayerName" };
 var layerMask =  LayerMask.GetMask(layerNames);

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Answer 4

Answer by shottogan · May 25, 2017 at 07:14 AM

If you simply make a public LayerMask var, multiple layers can be selected simultaneously in the dropdown.

 public LayerMask layerMask;

And then, for example:

 var standing = Physics2D.OverlapCircle( position, radius, layerMask );

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How do I use layermasks?

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