Image Image Image Image Image Image Image Image Image Image

/SKILL | December 6, 2019

Scroll to top

Top

OverlapCircleNonAlloc Layermask in Unity not working and the way to Fix it

OverlapCircleNonAlloc Layermask in Unity not working and the way to Fix it

Hey all,

I ran into this issue when I was trying to use OverlapCircleNonAlloc to find enemies within distance of each other for targeting.  It stumped me for about an hour until I came across this page.  At the bottom a very straight forward direction was left and it ended up working, pictured below.

After some research in the documentation here I understand the left shift operator in C# a little better also known as bit shift!  Upfront I will let you know that there is also a right-shift operator (>>).

The left-shift operator (<<) shifts its first operand left by the number of bits specified by its second operand. The type of the second operand must be an int or a type that has a predefined implicit numeric conversion to int. -Microsoft

In other words, << shifts bits over in a byte.  For example if an int is 32 bits and looks like this ‘00000000000000000000000000000001’ and you use this shift ‘1 << 8’ you move the 1 in that int over 8 times to look like this ‘00000000000000000000000100000000’.

What happens here is each movement on the bit to the left it doubles itself until it is a 256 (1 to 2 to 4 to 8 to 16 to 32 to 64 to 128 to 256) in the 8th position.  The logic is that Layers use an integer bit mask and there are 32 possible layers (check unity editor, starts at 0 and ends at 31).

So to simplify, if a bit is a 0 or a 1 and all Layers reside within a 32 bit integer, the way to find your layer within those 32 bits is to use a bit shift to find your layer.

  • Example: 1 << LayerMask.NameToLayer(“yourLayerName”)
  • Example: 1 << 8 (if 8 is your layer)
  • Example: 256 (because that is what the bit shift 8 spots over multiples out to, but the other ways make more sense if you want a visual of the layer you are calling out)

All of these will work.  I have no idea if I explained any of this the wrong way but hopefully it will help someone in the future.

See ya

1983 Views // February 20, 2018

Next Story

This is the most recent story.