# PhysicsMask > A 64-bit mask, effectively 64 flags. The default enumerator will iterate all the bits that are set (1). ## Definition * **Type:** Struct * **Namespace:** [UnityEngine.LowLevelPhysics2D](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d.md) * **Assembly:** UnityEngine.Physics2DModule * **Implements:** [IEnumerable\](https://learn.microsoft.com/dotnet/api/system.collections.generic.ienumerable-1), [IEnumerable](https://learn.microsoft.com/dotnet/api/system.collections.ienumerable) ```csharp public struct PhysicsMask : IEnumerable, IEnumerable ``` ## Fields | Value | Description | | ----------------------------------------------------------------------------------------------- | ------------------------------------ | | [bitMask](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/bitmask.md) | A 64-bit mask, effectively 64 flags. | ## Static Fields | Value | Description | | ----------------------------------------------------------------------------------------- | -------------------------------------------------------------------- | | [All](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/all.md) | All 64 bits set (1) in the PhysicsMask. | | [None](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/none.md) | No bits set in the PhysicsMask, effectively zero. | | [One](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/one.md) | Bit #0 set (1) in the PhysicsMask. The remaining bits are reset (0). | ## Constructors | Constructor | Description | | ------------------------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [PhysicsMask(System.Int32\[\])](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/ctor.md#physicsmask\(int\)) | Create a PhysicsMask by specifying multiple bits to set (1). | | [PhysicsMask(UnityEngine.LayerMask)](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/ctor.md#physicsmask\(layermask\)) | Create a PhysicsMask from a LayerMask. A [LayerMask](/engine/6000.3/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/6000.3/script-reference/unityengine/lowlevelphysics2d/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/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/resetbititerator.md). | | [setBits](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/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/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/setbititerator.md). | ## Methods | Method | Description | | ----------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [AreAnyBitsSet](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/areanybitsset.md) | Checks if any of the provided PhysicsMask set bits are also set in this PhysicsMask. | | [AreBitsSet](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/arebitsset.md) | Checks if all the provided PhysicsMask set bits are also set in this PhysicsMask. | | [IsBitSet](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/isbitset.md) | Is the specified bit set. | | [ResetBit](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/resetbit.md) | Reset (0) the specified bit. | | [SetBit](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/setbit.md) | Set (1) the specified bit. | | [ToLayerMask](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/tolayermask.md) | Convert the lower 32-bits of the 64-bit mask to the 32-bit [LayerMask](/engine/6000.3/script-reference/unityengine/layermask.md). A [LayerMask](/engine/6000.3/script-reference/unityengine/layermask.md) is only 32-bits wide so the upper 32-bits of the PhysicsMask will be ignored. | ## Classes | Class | Description | | ------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [PhysicsMask.ShowAsPhysicsMaskAttribute](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/showasphysicsmaskattribute.md) | When applied to a field/property of type [PhysicsMask](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask.md), the field/property drawer will not be display it as [PhysicsLayers](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/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 full layer editing is active (see [PhysicsLowLevelSettings2D.useFullLayers](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicslowlevelsettings2d/usefulllayers.md)). | ## Structs | Struct | Description | | ----------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [PhysicsMask.ResetBitIterator](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/resetbititerator.md) | An iterator that will iterate only the bits that are reset (0) in a [PhysicsMask](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask.md) | | [PhysicsMask.SetBitIterator](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask/setbititerator.md) | An iterator that will iterate only the bits that are set (1) in a [PhysicsMask](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicsmask.md) |