.. _doc_assets_physics_material:

Physics Material Assets
=======================

Work-in-progress feature to allow custom physics effects rather than hardcoding them.

The ``PhysicsMaterialAsset`` type associates gameplay properties and effects with custom Unity "physic" materials. For example if none of the built-in physics materials has appropriate effects for the surface of Mars, a custom Unity physics material named "MarsDirt" could be created. Then a physics material asset with ``UnityName`` set to "MarsDirt" and ``Fallback`` of 33650ff924b34f8d9c5a0fd97418cd3e (built-in gravel) could add custom effects for the Martian surfaces.

The ``PhysicsMaterialExtensionAsset`` type can be used to insert custom properties into built-in physics materials. For example if a custom laser gun should leave burn marks on the hit surface rather than bullet holes, an extension asset can set the ``Base`` property to a built-in physics material to add custom effects.

Properties
----------

**Type** *string*: ``SDG.Unturned.PhysicsMaterialAsset`` or ``SDG.Unturned.PhysicsMaterialExtensionAsset``

**UnityName** *string* or ``UnityNames`` *string array*: Names of Unity "physic" materials to associate with this asset. Not set by extension assets. Multiple names can be specified as an array because the old built-in physics materials had several variants for special cases that should now be handled by these assets.

**Fallback** :ref:`Asset Pointer <doc_data_assetptr>`: Points to a different physics material asset. Fallbacks are used when a property is not set. For example the snow physics material does not have a bullet casing bounce audio clip, so the gravel fallback is used instead.

**Base**  :ref:`Asset Pointer <doc_data_assetptr>`: Points to a physics material asset to extend. Properties from the extension asset will be appended to the base asset.

**AudioDefs** *dictionary*: pairs of key/name and :ref:`Master Bundle Pointer <doc_data_masterbundleptr>` to OneShotAudioDefinition. For example the ``ParticleSystemCollisionAudio`` component ``MaterialPropertyName`` is referring to these keys. Official properties include:

- BulletCasingBounce: used by vanilla non-shotgun particle collision audio.
- BulletImpact: fired bullet hitting surface.
- BipedLand: player landing on a surface after falling. Could be used for other two-legged characters (zombies) in the future.
- FootstepWalk: individual non-sprinting footstep.
- FootstepRun: individual sprinting footstep.
- LegacyImpact: will probably be phased-out. Still used by vehicle bumper collision and as a fallback for melee impact.
- MeleeImpact: melee attack hitting surface.
- ShotgunShellBounce: used by vanilla shotgun particle collision audio.

**TireMotionEffect** :ref:`Asset Pointer <doc_data_assetptr>` to :ref:`Effect Asset <doc_assets_effect>`: Effect to spawn while driving on this material. Its transform is set to the ground hit position with the Z axis aligned to the wheel's up vector and rotated according to forward/reverse speed. The vanilla effects use the rate over distance emission mode.

**IsArable** *bool*: If true, crops can be planted on this material.

**HasOil** *bool*: If true, oil drills can be placed on this material. Note at the time of writing (2022-02-10) oil drills can only be placed on terrain materials.

**Character_Friction_Mode** *enum* (``ImmediatelyResponsive``, ``Custom``): If custom the acceleration, deceleration, and max speed properties are used. Replacement for the hardcoded ice and slippery metal plate.

**Character_Acceleration_Multiplier** *float*: Default acceleration is equal to the target move speed.

**Character_Deceleration_Multiplier** *float*: Default deceleration is 2m/s².

``Character_Max_Speed_Multiplier`` *float*: Allows speed to reach up to this multiplied by the target move speed.