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Simple Physics Toolkit

A set of drop-in MonoBehaviour components for common physics manipulation tasks. Requires no coding — just drag, drop, and configure.

Author: Dylan Anthony Auty

Simple Physics Toolkit Showcase

Getting Started

  1. Import the package into your Unity project
  2. Attach any component below to a GameObject
  3. Configure settings in the Inspector
  4. Play your scene

Sample scenes for every component are in Samples/.

Components Overview

Component Description 3D 2D
Magnet Attract/repel Rigidbodies within a radius ✓ ✓
Explosive Apply explosive impulse force to nearby objects ✓ ✓
Buoyancy Mesh-based fluid simulation with waves/forces ✓ —
Wind Push objects in a direction within a zone ✓ ✓
ZeroGravity Disable gravity inside a trigger zone ✓ —
BouncePlate Apply upward impulse force on contact ✓ —
ProjectileSpawn Spawn and fire projectiles at intervals ✓ —
ThrustEngine Apply thrust force with optional hover mode ✓ —
Rope Create a chain of CharacterJoints between two points ✓ —
ParticleInfluencer Attract/repel Particle Systems via force fields ✓ —
DestroyObjects / Killzone2D Destroy objects that enter a trigger zone ✓ ✓
InteractableItem Marker/tag filter component ✓ ✓

Utility Components

Component Description
ConstantForceZone Directional, radial, or vortex force applied inside a trigger zone
PhysicsMaterialApplier Auto-apply physics materials and drag values on zone enter/exit
DragZone Apply linear/angular drag inside a zone with optional velocity cap
JointConnector Create configurable joints between two objects

Interaction System

Component Description
Interactable Marks objects as pickuppable; configures hold and throw settings
InteractionController Player-side controller for pickup, drop, throw via mouse/keyboard

Debug & Presets

Component / Asset Description
PhysicsDebugger Editor-only overlay showing active physics zones and force ranges
PhysicsPreset ScriptableObject asset that stores component settings for reuse

Component Details

Magnet (3D) / Magnet2D (2D)

Magnet Inspector

Attracts or repels Rigidbodies within a spherical radius.

Key Settings:

  • magnetForce — Strength of the force
  • attract — Attract or repel mode
  • innerRadius / outerRadius — Dead zone and max range
  • useColliderAsTrigger — Use a custom collider shape instead of sphere
  • realismMode — Distance-based force falloff (Newtonian)
  • onlyAffectInteractableItems — Only affect objects with InteractableItem
  • onAffect — UnityEvent invoked when force is applied

2D Notes: Uses OverlapCircleAll with Rigidbody2D. No useColliderAsTrigger mode.

Explosive (3D) / Explosive2D (2D)

Explosive Inspector

Destroys itself and applies explosive impulse force to nearby Rigidbodies.

Key Settings:

  • power — Explosion force magnitude
  • radius — Blast radius
  • explosionPrefab — Optional VFX prefab to spawn
  • onExplode / onApplyForce — UnityEvents
  • onlyAffectInteractableItems — Filter mode

Triggers: OnTriggerEnter or OnCollisionEnter when a Rigidbody touches it.

2D Notes: Uses AddForce with direction away from center (2D has no AddExplosionForce).

Buoyancy (3D only)

Buoyancy Scene Example

Advanced fluid simulation with mesh-based submerged volume calculation. Replaces the legacy Water.cs.

Key Settings:

  • fluidDensity — Default 1027 (seawater)
  • visualizeForces — Debug ray visualization
  • CalculatePressureForces / CalculateSlammingForces — Advanced force modes
  • slammingMultiplier — Impact force scaling
  • onFluidEnter / onFluidExit — UnityEvents

How it works: Adds a BuoyantItem component at runtime to entering objects. BuoyantItem reads the mesh data, calculates submerged volume per triangle, and applies buoyancy, viscous resistance, optional pressure drag, and optional slamming forces.

Requirements: Rigidbody + MeshFilter on entering objects.

Wind (3D) / Wind2D (2D)

Wind Gizmo Visualization

Applies continuous force to Rigidbodies inside its trigger collider.

Key Settings:

  • lift — Force magnitude
  • directionMode — Choose LocalUp, LocalForward, WorldUp, or WorldForward
  • onlyAffectInteractableItems — Filter
  • onAffect — UnityEvent (3D only)

Direction: Rotate the GameObject to control wind direction. Use directionMode to switch axes.

ZeroGravity (3D only)

Disables/enables gravity for Rigidbodies entering/exiting a trigger zone.

Key Settings:

  • zeroGravityDrag — Drag applied inside the zone (default 0.5)
  • normalGravityDrag — Drag restored on exit (default 0.0)
  • onlyAffectInteractableItems — Filter

Note: Also handles script enable/disable toggling gracefully.

BouncePlate (3D only)

Applies upward impulse force to Rigidbodies that touch the trigger.

Key Settings:

  • bounce — Impulse force magnitude
  • onlyAffectInteractableItems — Filter
  • onBounce — UnityEvent

ProjectileSpawn (3D only)

Periodically spawns and fires projectiles from a random selection.

Key Settings:

  • emitRate — Time between shots
  • speed — Projectile speed
  • inaccuracy — Spread via Random.insideUnitSphere
  • addRandomInertiaToProjectiles — Occasional torque
  • limitObjectsInScene / limitAmount — Object limiting / pseudo-pooling
  • objects — Array of projectile prefabs to choose from

ThrustEngine (3D only)

Thrust Engine Inspector

Applies thrust force at position, with optional hover mode.

Key Settings:

  • maxPower — Maximum thrust force
  • currentPowerPercentage — Throttle (0–1)
  • hoverMode — Switch to hover dynamics
  • hoverDistance — Desired altitude
  • hoverSafeRange — Dead zone above hover distance
  • boundObject — Target Rigidbody

Rope (3D only)

Rope Scene Example

Creates a chain of CharacterJoints between two points for rope physics.

Note: Rope system is in beta. Behaviour may change in future updates.

Key Settings:

  • connectedBody — Target endpoint
  • isAnchor — First segment is kinematic (fixed)
  • resolution — Number of segments
  • renderRope / ropeWidth / ropeColor — Visual settings
  • simpleRopeCollisions — SphereColliders on mid-segments
  • ropeSegmentMass — Mass per segment
  • jointTwistLimit / jointSwingLimit — CharacterJoint angle limits
  • jointBreakForce / jointBreakTorque — Break thresholds

ParticleInfluencer (3D only)

Attracts or repels Unity Particle Systems using ParticleSystemForceField.

Key Settings:

  • attract — Attract or repel
  • forceMultiplier — Strength
  • drag — Force field drag
  • range — Force field range

Note: Operates on all ParticleSystems in the scene.

DestroyObjects (3D) / Killzone2D (2D)

Destroys any GameObject that enters its trigger. Useful for scene cleanup.

Key Settings:

  • onDestroy — UnityEvent before destruction (3D only)

InteractableItem (3D & 2D)

Empty marker/tag component. Used as a filter when onlyAffectInteractableItems is enabled on other components.

Utility Components

ConstantForceZone

Applies constant force to Rigidbodies within a trigger zone.

Force Shapes: Directional (fixed direction), Radial (toward/away from center), Vortex (tangential spin)

Settings: forceDirection, forceMagnitude, forceMode, onAffect event.

PhysicsMaterialApplier

Auto-apply physics materials and drag values when objects enter/exit a zone.

Settings: Separate enter/exit material, drag, and angular drag values. Events on enter/exit.

Set drag values to -1 to leave unchanged.

DragZone

Applies linear/angular drag to objects inside a zone with optional velocity cap.

Settings: drag, angularDrag, maxVelocity (0 = no limit). Events on enter/exit.

JointConnector

Creates configurable joints between two objects at runtime or on demand.

Joint Types: Fixed, Hinge, Spring, Configurable. Automatically adds a Rigidbody if missing.

Interaction System

Interactable

Attach to objects that the player should be able to pick up, hold, and throw.

Settings:

  • holdMode — Fixed, Spring, or Configurable joint
  • holdDistance — Distance from camera when held
  • maxPickupMass — Mass limit for pickup
  • throwForce / throwUpwardForce — Throw velocity
  • highlightColor — Visual feedback on hover
  • Events: onPickup, onDrop, onThrow

Requirements: Rigidbody.

InteractionController

Attach to the player camera. Handles raycasting, pickup, hold, and throw.

Settings:

  • Key bindings: pickupKey (default Mouse0), throwKey (default Mouse1), dropKey (default G)
  • pickupRange — Max distance for interaction
  • pickupLayers — Layer mask filtering
  • holdPoint — Transform where held objects position

Input Support: Mouse, keyboard, touch (via Input Manager).

Physics Presets

PhysicsPreset ScriptableObjects let you save and reuse component configurations.

To create a preset:

  1. Right-click in the Project window → Create → Simple Physics Toolkit → Physics Preset
  2. Name it and configure the float/bool values (field names must match component field names)
  3. Assign the preset to a component's componentPreset field
  4. Click Apply Preset in the inspector to copy values into the component

Physics Debugger

The PhysicsDebugger component shows active physics zones in the Scene view.

Modes: Off, Zones, Forces, All. Cycle with F12 (configurable).

Useful for scene setup and troubleshooting.

Legacy Components

Component Replacement Status
Water.cs Buoyancy.cs Deprecated, remains for backwards compatibility
Readme-Overview.txt This README Superseded
Overview PDF This README Superseded

Legacy documentation is in Documentation/Legacy/.

Support

For issues, feature requests, or questions, please get in touch via the Asset Store page.

Suggestions for improvements and additional features are always welcome!