erincatto/box2d
Box2d
Box2D is a 2D physics engine and rigid body simulator designed to compute collisions, forces, and joints in a two-dimensional plane. It functions as a collision detection library and a constraint-based physics solver that calculates the movement and interaction of solid objects using mass, friction, and restitution properties.
The engine ensures consistency across different hardware architectures through a deterministic trigonometry implementation. It prevents high-speed objects from passing through boundaries using continuous collision detection and time-of-impact interpolation.
The system covers rigid body dynamics and constraint-based animation, allowing bodies to be connected via joints and motors. It includes tools for spatial querying, ray casting, and sensor overlap detection, alongside a solver that manages iterative impulse integration and object penetration prevention.
Users can customize the simulation through length scaling configuration and a custom memory allocator to manage memory usage for performance tuning.
Features
- 2D Rigid Body Physics Engines - Provides a comprehensive engine for calculating realistic physical interactions, collisions, and dynamics for 2D objects.
- Collision Detection - Identifies intersections between physical shapes using continuous detection and filtering systems.
- Penetration Prevention - Generates contact constraints to stop bodies from overlapping while simulating friction and restitution.
- Body Type Definitions - Defines physical objects as dynamic, static, or kinematic to determine how they react to forces.
- Continuous Collision Detection - Prevents high-speed objects from passing through boundaries using bullet-mode marking and continuous detection.
- Physical Material Properties - Provides definitions for physical characteristics like density and friction that determine how bound shapes interact.
- Mass Property Calculation - Computes the mass, centroid, and rotational inertia for a shape to determine force reactions.
- Fixture Shape Definitions - Provides interfaces for constructing collision geometries using circles, polygons, edges, and chains.
- Mechanical Constraints - Provides tools for linking and constraining the movement of physical bodies through joints and motors.
- Mechanical Joint Constraints - Holds multiple bodies together using joints that support limits and motors to control relative motion.
- Physics World Management - Initializes the simulation environment with gravity and manages the lifecycle of all bodies and shapes.
- Deterministic State Simulation - Ensures consistent simulation results across different hardware architectures using a deterministic trigonometry implementation.
- Sequential Impulse Solvers - Uses an iterative sequential impulse solver to resolve constraints and update object velocities for physical stability.
- Time-of-Impact Interpolations - Prevents high-speed objects from passing through boundaries by calculating the exact moment of first contact.
- Force and Impulse Applications - Provides an API for applying linear forces, angular torques, and immediate impulses to rigid bodies.
- Contact Event Systems - Allows toggling reporting for hit events and sensor overlaps for specific shapes.
- Game Physics Integration - Integrates physics simulation to handle collisions, trigger sensors, and forces within a game world.
- Simulation Event Triggers - Sends notifications for body movement and contact interactions so applications can react to changes.
- Continuous Collision Detection - Uses time-of-impact interpolation to ensure fast-moving objects do not pass through each other.
- Spatial Partitioning Systems - Implements spatial partitioning to optimize collision detection by pruning distant objects using axis-aligned bounding boxes.
- Physical Body Management - Adjusts gravity scaling and damping to control movement and determine when objects enter a sleep state.
- Rigid Body Transform Management - Handles rotation and translation of objects and computes relative transformations between different coordinate frames.
- Collision Event Handlers - Collects deterministic lists of hit events after a time step to handle collision logic.
- Collision Notification Filters - Provides bitmasks and group indices to filter which physical shapes should interact or be ignored.
- Overlap Detection - Retrieves lists of shapes overlapping sensors or specific points where shapes touch.
- Ray and Shape Casting - Deno Physics detects intersections by projecting a ray or moving shape through space to find the first point of contact.
- Spatial Querying Systems - Locates objects using bounding box queries or ray casts to detect overlaps and find targets in the world.
- Degrees of Freedom Restriction - Creates physical connections that remove degrees of freedom to simulate pinned points or restricted motion.
- Collision Edge Chains - Deno Physics constructs connected line segments to create complex boundaries or terrain for objects to collide with.
- Kinematic Motion Control - Sets target transforms for kinematic bodies to calculate the necessary velocity to reach a position.
- Deterministic Calculation Utilities - Uses a custom deterministic trigonometry implementation to ensure consistent simulation results across different hardware platforms.
- Contact Pre-Solve Modifications - Intercepts collision data via a callback before the solver runs to customize or disable specific physical interactions.
- Sensor Overlap Detections - Identifies when objects enter or exit trigger areas defined as sensors to separate trigger logic from physical contact.
- Physics and Simulation - Battle-tested 2D physics for games.
- Physics Simulation - 2D physics engine for games.
