Physics Settings

Physics Settings asset is used to specify the initial physics simulation configuration. In fact, some of its options can be set only on physics engine startup so using that asset may be required. Hovewer, most of the physics simulation options can be adjusted at runtime using Physics class.

Create physics settings

1. Navigate to the Content directory in the Content window

2. Right-click and select option New -> Settings, specify the asset name (eg. Physics Settings) and hit Enter
   

3. Choose option Physics Settings and press Create button
   

4. Double-click on an asset to open it and edit
   

Use physics settings

You can create as many physics settings as you want (even special versions per platform) but only one can be used during game building. Use Game Settings asset (always located in Content/GameSettings.json) to link the physics options. If your game is using more advanced configuration you can edit the game settings from code in your build script (use GameSettings.Load and GameSettings.Save from C# API).

Simulation options

Property	Description
Default Gravity	The default gravity force value (in cm^2/s).
Queries Hit Triggers	If checked, any raycast or other scene query that intersects with a collider marked as a trigger will returns with a hit. Individual raycasts can override this behavior.
Triangle Mesh Triangle Min Area Threshold	Triangles from triangle meshes (CSG) with an area less than or equal to this value will be removed from physics collision data. Set to less than or equal 0 to disable.
Bounce Threshold Velocity	Minimum relative velocity required for an object to bounce. A typical value for simulation stability is about 0.2 * gravity.
Friction Combine Mode	The default friction combine mode, controls how friction is computed for multiple materials.
Restitution Combine Mode	The default restitution combine mode, controls how restitution is computed for multiple materials.
Disable CCD	If checked, CCD will be ignored. This is an optimization when CCD is never used which removes the need for physics engine to check it internally.
Enable Adaptive Force	Enables adaptive forces to accelerate convergence of the solver. Can improve physics simulation performance but lead to artifacts.

Tip

When Continuous Collision Detection (CCD) is turned on, the affected rigid bodies will not go through other objects at high velocities (a problem also known as tunnelling).

Framerate options

Property	Description
Max Delta Time	The maximum allowed delta time (in seconds) for the physics simulation step.
Enable Substepping	Whether to substep the physics simulation.
Substep Delta Time	Delta time (in seconds) for an individual simulation substep.
Max Substeps	The maximum number of substeps for physics simulation.

Layers Matrix options

Flax physics simulation supports layer-based collision detection. You can specify collisions mask for each layer that will be used to describe if objects from that layer can collide with objects from the other layers.

This uses the global layers settings and shows them as a layers matrix. Use checkboxes to define the layers collision mask.

Other

Property	Description
Support Cooking At Runtime	Enables support for cooking physical collision shapes geometry at runtime. Use it to enable generating runtime terrain collision or convex mesh colliders.