# PhysicsCore 2D project settings reference > Learn about Physics Core 2D API settings. The following Project settings manage the global settings for the Physics Core 2D API. > **Note:** > > This documentation is about writing C# scripts using the `Unity.U2D.Physics` API. To use 2D physics in the Unity Editor using components like the Rigidbody 2D component, refer to [2D physics](/engine/6000.5/manual/unity2d/2d-physics.md.md) instead. To open the PhysicsCore 2D project settings window, go to **Edit** > **Project Settings…** > **PhysicsCore 2D**. > **Note:** > > To manage the global settings for 3D physics instead, refer to the [Physics project settings reference](/engine/6000.5/manual/unity-editor/editor-settings-reference/comp-manager-group/class-physics-manager.md). | **Property** | **Description** | | ------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Physics Core Settings** | Assigns a set of global settings for physics objects and the physics simulation when you use the Physics Core 2D API. For more information, refer to [Configure global Physics Core 2D API settings](/engine/6000.5/manual/unity2d/2d-physics-api/properties/class-physics-core-settings2d.md). | ## Settings The settings tab contains the settings from the **PhysicsCore Settings** file. ### Layers The properties in this section configure the layers Unity uses to detect collision. For more information, refer to [Configure collisions between Physics Core 2D API objects](/engine/6000.5/manual/unity2d/2d-physics-api/interactions/collisions-enable.md). | **Property** | **Description** | | ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Physics Layer Names** | Sets the names of the 64 layers the `PhysicsMask` API uses if you enable **Use Full Layers**. By default, the first layer has the name **Default** and the other layers have no name. | ### Default Definitions The properties in this section set the default values when you create a new definition object. For the individual sections, refer to the following: #### General * [World definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/world.md) * [Body definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/body.md) * [Shape definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/shape.md) * [Chain definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/chain.md) #### Joints * [Distance joint definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/joint-distance.md) * [Fixed joint definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/joint-fixed.md) * [Hinge joint definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/joint-hinge.md) * [Relative joint definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/joint-relative.md) * [Slider joint definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/joint-slider.md) * [Wheel joint definition reference](/engine/6000.5/manual/unity2d/2d-physics-api/reference/joint-wheel.md) ### Global | **Property** | **Description** | | -------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Transform Change Mode** | Sets when Unity sends notifications to callbacks when the transform of a physics body changes. The options are:**Off**: Doesn't send notifications.**Frame Start**: Sends notifications at the start of the frame.**Fixed Update**: Sends notifications during the `FixedUpdate` event stage.**Update**: Sends notifications during the `Update` event stage.For more information, refer to [Event functions](/engine/6000.5/manual/scripting/managing-update-order/event-functions.md). | | **Contact Filter Mode** | Determines when Unity reports a contact event between two shapes that have contact filters. The options are:**Both**: Reports a contact event only if both shapes have contact filters that include each other.**Either**: Reports a contact if either shape has a contact filter that includes the other.For more information, refer to [`PhysicsShape.ContactFilter`](/engine/6000.5/script-reference/unity/u2d/physics/physicsshape/contactfilter.md). | | **Rendering Mode** | Determines whether Unity draws a debug visualization in a built project. The options are:**Editor Only**: Draws only in the Unity Editor.**Development Player**: Draws in the Editor, and a built project if **Development Build** is enabled. For more information, refer to [Build Profiles window reference](/engine/6000.5/manual/building-and-publishing/build-settings/build-profiles-reference.md).**Any Player**: Draws in the Editor and built projects.For more information, refer to [Draw a debug visualization of objects](/engine/6000.5/manual/unity2d/2d-physics-api/create-objects/debug-drawing.md). | | **Maximum Worlds** | Sets the maximum number of worlds that can exist at the same time. Unity always creates one physics world by default. | | **Concurrent Simulations** | Sets the number of physics simulations that can run at the same time. The default is 2. | | **Length Units Per Meter** | Sets the number of Unity units that correspond to one meter in the physics simulation. The default is 1. | | **Use Physics Layers** | Enables the `PhysicsMask` API using the 64 layers in the **Layers** tab. If you disable this property, the `PhysicsMask` API uses the 32 [GameObject layers](/engine/6000.5/manual/working-with-gameobjects/layers.md) instead. | | **Disable Simulation** | Stops the simulation. You can still use the API as normal while the simulation is stopped. | | **Always Draw Worlds** | Creates a `DrawResults` object with the debug draw visualization, even if you set **Rendering Mode** to disable drawing in a built project. For more information, refer to [PhysicsWorld.DrawResults](/engine/6000.5/script-reference/unity/u2d/physics/physicsworld/drawresults.md). | ## Additional resources * [2D physics with the Physics Core 2D API](/engine/6000.5/manual/unity2d/2d-physics-api.md)