AgentSkillsCN

Setting Up Physics

配置物理引擎、碰撞检测、刚体以及各类物理交互

SKILL.md
--- frontmatter
description: Setting up physics, collisions, rigidbodies, and physical interactions

Setting Up Physics

Use this skill when objects need to fall, bounce, collide, be pushed, or have any physical behavior.

Trigger Phrases

  • •"fall", "gravity", "drop"
  • •"bounce", "bouncy"
  • •"collide", "collision", "hit"
  • •"push", "physics"
  • •"roll", "slide"

When to Apply (Automatically)

Apply physics when:

  • •Objects need to fall (gravity)
  • •Objects need to collide with each other
  • •Objects need trigger detection (OnTriggerEnter)
  • •Objects need to be pushed or affected by forces
  • •Objects need realistic movement

Implementation Checklist

  1. •

    Add Rigidbody

    • •useGravity: true for falling objects, false for floating
    • •isKinematic: true for script-controlled, false for physics-controlled
    • •mass: affects push/pull behavior
    • •drag: slows movement over time
  2. •

    Add Colliders

    • •Primitive (Box, Sphere, Capsule) preferred for performance
    • •Mesh Collider only when needed (convex for moving objects)
    • •isTrigger = true for detection without physical collision
  3. •

    Physics Materials (optional)

    • •Bounciness: 0 (no bounce) to 1 (full bounce)
    • •Friction: 0 (ice) to 1+ (sticky)
  4. •

    Layer Collision Matrix

    • •Configure which layers collide with which
    • •Optimize by disabling unnecessary collisions

Common Setups

Falling Object (Crate, Ball)

code
Rigidbody:
  - useGravity: true
  - isKinematic: false
  - mass: 1-10 based on size

Collider:
  - BoxCollider or SphereCollider
  - isTrigger: false

Trigger Zone (Pickup, Damage Area)

code
Rigidbody:
  - useGravity: false
  - isKinematic: true

Collider:
  - isTrigger: true

Projectile (Bullet, Laser)

code
Rigidbody:
  - useGravity: false
  - isKinematic: true
  - collisionDetectionMode: Continuous (for fast objects)

Collider:
  - isTrigger: true

Player Character

code
Option A - CharacterController:
  - More precise, less physics-y
  - Good for platformers

Option B - Rigidbody:
  - useGravity: true
  - constraints: Freeze rotation X, Z
  - Good for physics-based games

Gotchas to Remember

  1. •

    Triggers need Rigidbody: OnTriggerEnter only fires if at least one object has a Rigidbody

  2. •

    Kinematic vs Dynamic:

    • •Kinematic: moved by scripts, not affected by physics
    • •Dynamic: moved by physics forces
  3. •

    Collision Detection:

    • •Discrete: default, can miss fast objects
    • •Continuous: catches fast objects, more expensive
  4. •

    Layer Matrix: If collisions aren't working, check Edit > Project Settings > Physics

Physics Materials

Bouncy Ball

code
bounciness: 0.8
dynamicFriction: 0.2
staticFriction: 0.2
bounceCombine: Maximum

Ice/Slippery

code
bounciness: 0
dynamicFriction: 0.05
staticFriction: 0.05
frictionCombine: Minimum

Sticky/High Friction

code
bounciness: 0
dynamicFriction: 1
staticFriction: 1

Output to User

Don't mention physics jargon. Say:

  • •"Now the crates will fall and you can push them"
  • •"The ball bounces off walls"
  • •"Walking into the coin picks it up"