Layer Mask

RAYCASTING | ADVANCED PARAMETERS

Layer Mask specifies layers to use in a Physics.Raycast

• GameObject can use up t4o 32 Layer Masks supported by the Editor

  • Layers 0,1,2,4, & 5 are used by Unity by default

  • Other 24 are controllable by the user

VISUAL REPRESENTATION OF LAYER MASK

A layer mask is essentially a 32 bit integer

--> Each bit represents an individual layer and defines them as 1 <on/true> or 0 <off/false>

--> Each bit is used to describe whether the layer is used

VISUAL REPRESENTATION OF LAYER BITMASK

LAYERMASK WITHIN UNITY

Unity, by default, uses layers 0, 1, 2, 4, & 5 for

Using a layer mask in correlation with raycasting allows the program only detect certain collisions with your ray.

HOW TO DETECT A LAYER WITHIN CODE...

There are two types of ways we can have the raycast detect whether a layer is on or off when it collides with an object.

1. String Value
2. Bitwise Operator

STRING VALUE

To check whether or not a gameobject has a specific layer enabled through the use of its string value we need to follow two steps.

1. STEP ONE --> Create a variable to store the layerMask's string value

2. STEP TWO --> Create a Raycast that will detect laymasks through a string value

STEP ONE

=>Create a variable to hold the wanted layer <Variable can be serializable for easy modification within Unity's Editor>

[SerializeField]
LayerMask _mask = LayerMask.GetMask("Enemy")

• LayerMask.GetMask(layerNames) --> returns the layer mask created from the parameter layerNames

STEP TWO

=>Create a RayCast that will be able to detect if the gameobject the rayCast collided with has the layer "Enemy" enabled

Physics.Raycast(transform.position, Vector3.forward, 10, _mask)

The above line of code creates a raycast that starts at the position of the attached gameobject and casts a ray 10 units forward. If the raycast hits another collider, the program checks to see whether or not that gameobject has the layer "Enemy" enabled. --> If it does, then the raycast returns true --> If it doesn't, then the raycast returns false

The Downfall to using the string value to check layer masks is because you can only check 1 layer at a time.

BITWISE OPERATOR

To check whether or not a gameobject has a specific layer enabled through the use of its integer value we need to accomplish the following steps.

1. Check Unity on what the integer value is assigned to the chosen layer.

2. Create a variable to store the layerMask's integer value

3. Create a Raycast that will detect layermasks through the use of a bitwise shift operator

STEP ONE

=> Check Unity's layer settings to get the integer value of the necessary layers

"Enemy" layer is assigned to int value 6, as shown above.

TO ACCESS TAGS/LAYERS

EDIT > PROJECT SETTINGS > TAGS AND LAYERS > LAYERS

STEP TWO

=> Create a Raycast that will detect layermasks through the use of a bitwise shift operator

Physics.Raycast(transform.position, Vector3.forward, 10, 1 << 6)

The layermask 1 << 6 uses a bitwise shift operator to tell unity to only detect objects who have layermask 6 active.

HOW TO DETECT MULTIPLE LAYERS

To detect multiple layers you must use the BITWISE OPERATOR

1 << 6 | 1 << 8 --> Checks whether layer 6 OR layer 8 is active