# PhysicsMask > A 64-bit mask, effectively 64 flags. The default enumerator will iterate all the bits that are set (1). ## Definition * **Type:** Struct * **Namespace:** [Unity.U2D.Physics](/engine/6000.7/script-reference/unity/u2d/physics.md) * **Assembly:** UnityEngine.PhysicsCore2DModule * **Implements:** [IEnumerable\](https://learn.microsoft.com/dotnet/api/system.collections.generic.ienumerable-1), [IEnumerable](https://learn.microsoft.com/dotnet/api/system.collections.ienumerable), [IEquatable\](https://learn.microsoft.com/dotnet/api/system.iequatable-1) ```csharp public struct PhysicsMask : IEnumerable, IEnumerable, IEquatable ``` ## Remarks Use a `PhysicsMask` together with [PhysicsLayers.GetLayerMask](/engine/6000.7/script-reference/unity/u2d/physics/physicslayers/getlayermask.md) and [PhysicsShape.ContactFilter](/engine/6000.7/script-reference/unity/u2d/physics/physicsshape/contactfilter.md) to control which objects collide with each other in a script. If the field or property that stores a `PhysicsMask` represents a raw bitmask rather than a set of named layers, apply [PhysicsMask.ShowAsPhysicsMaskAttribute](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/showasphysicsmaskattribute.md) so Unity displays it as bit values in the Inspector window. Additional Resources: [PhysicsLayers.GetLayerMask](/engine/6000.7/script-reference/unity/u2d/physics/physicslayers/getlayermask.md), [PhysicsShape.ContactFilter](/engine/6000.7/script-reference/unity/u2d/physics/physicsshape/contactfilter.md) ## Examples ```csharp // Get the physics mask for the "Car" layer, then get another mask for the // layers the object should collide with. using UnityEngine; using Unity.U2D.Physics; public class PhysicsMaskExample : MonoBehaviour { void Start() { PhysicsMask objectLayer = PhysicsLayers.GetLayerMask("Car"); PhysicsMask contactLayer = PhysicsLayers.GetLayerMask("Walls"); PhysicsShape.ContactFilter myContactFilter = new PhysicsShape.ContactFilter { categories = objectLayer, contacts = contactLayer }; } } ``` ## Fields | Value | Description | | ----------------------------------------------------------------------------------- | ------------------------------------ | | [bitMask](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/bitmask.md) | A 64-bit mask, effectively 64 flags. | ## Static Fields | Value | Description | | ----------------------------------------------------------------------------- | -------------------------------------------------------------------- | | [All](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/all.md) | All 64 bits set (1) in the PhysicsMask. | | [None](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/none.md) | No bits set in the PhysicsMask, effectively zero. | | [One](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/one.md) | Bit #0 set (1) in the PhysicsMask. The remaining bits are reset (0). | ## Constructors | Constructor | Description | | ------------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [PhysicsMask(System.Int32\[\])](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/ctor.md#physicsmask\(int\)) | Create a PhysicsMask by specifying multiple bits to set (1). | | [PhysicsMask(UnityEngine.LayerMask)](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/ctor.md#physicsmask\(layermask\)) | Create a PhysicsMask from a LayerMask. A [LayerMask](/engine/6000.7/script-reference/unityengine/layermask.md) is only 32-bits wide so the PhysicsMask will have the upper 32-bits set to zero. | ## Properties | Property | Description | | --------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [resetBits](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/resetbits.md) | Gets an enumerable group of bits that are currently reset (0). The bits are returned in ascending bit-index order. This uses [PhysicsMask.ResetBitIterator](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/resetbititerator.md). | | [setBits](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/setbits.md) | Gets an enumerable group of bits that are currently set (1). The bits are returned in ascending bit-index order. This uses [PhysicsMask.SetBitIterator](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/setbititerator.md). | ## Methods | Method | Description | | ----------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [AreAnyBitsSet](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/areanybitsset.md) | Checks if any of the provided PhysicsMask set bits are also set in this PhysicsMask. | | [AreBitsSet](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/arebitsset.md) | Checks if all the provided PhysicsMask set bits are also set in this PhysicsMask. | | [IsBitSet](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/isbitset.md) | Is the specified bit set. | | [ResetBit](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/resetbit.md) | Reset (0) the specified bit. | | [SetBit](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/setbit.md) | Set (1) the specified bit. | | [ToLayerMask](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/tolayermask.md) | Convert the lower 32-bits of the 64-bit mask to the 32-bit [LayerMask](/engine/6000.7/script-reference/unityengine/layermask.md). A [LayerMask](/engine/6000.7/script-reference/unityengine/layermask.md) is only 32-bits wide so the upper 32-bits of the PhysicsMask will be ignored. | ## Operators | Operator | Description | | ------------------------------------------------------------------------------------------------- | --------------------------------------------- | | [operator &](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/op-bitwiseand.md) | Bitwise AND operator for PhysicsMask. | | [operator \|](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/op-bitwiseor.md) | Bitwise OR operator for PhysicsMask. | | [operator ^](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/op-exclusiveor.md) | Bitwise XOR operator for PhysicsMask. | | [operator \<\<](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/op-leftshift.md) | Bitwise LEFT-SHIFT operator for PhysicsMask. | | [operator \~](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/op-onescomplement.md) | Bitwise COMPLEMENT operator for PhysicsMask. | | [operator >>](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/op-rightshift.md) | Bitwise RIGHT-SHIFT operator for PhysicsMask. | ## Classes | Class | Description | | ------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [PhysicsMask.ShowAsPhysicsMaskAttribute](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/showasphysicsmaskattribute.md) | When applied to a field/property of type [PhysicsMask](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask.md), the field/property drawer will not be display it as [PhysicsLayers](/engine/6000.7/script-reference/unity/u2d/physics/physicslayers.md). Instead, the field/property will be displayed as bit numbers only i.e. a raw 64-bit mask allowing each bit to be (de)selected. This is only used when physics layers are active (see [\_usePhysicsLayers](/engine/6000.7/script-reference/unity/u2d/physics/physicscoresettings2d/usephysicslayers.md)). | ## Structs | Struct | Description | | ----------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- | | [PhysicsMask.ResetBitIterator](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/resetbititerator.md) | An iterator that will iterate only the bits that are reset (0) in a [PhysicsMask](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask.md) | | [PhysicsMask.SetBitIterator](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask/setbititerator.md) | An iterator that will iterate only the bits that are set (1) in a [PhysicsMask](/engine/6000.7/script-reference/unity/u2d/physics/physicsmask.md) |