rapier

Pros of Bullet3

• More mature and widely adopted in industry, with extensive documentation and community support
• Supports a broader range of features, including soft body dynamics and fluid simulation
• Cross-platform compatibility, including support for various game engines and 3D modeling software

Cons of Bullet3

• Written in C++, which may be less accessible for developers primarily working with higher-level languages
• Can be more complex to set up and integrate, especially for simpler projects
• Performance may be slower for certain use cases compared to more specialized libraries

Code Comparison

Bullet3:

btDefaultCollisionConfiguration* collisionConfiguration = new btDefaultCollisionConfiguration();
btCollisionDispatcher* dispatcher = new btCollisionDispatcher(collisionConfiguration);
btBroadphaseInterface* overlappingPairCache = new btDbvtBroadphase();
btSequentialImpulseConstraintSolver* solver = new btSequentialImpulseConstraintSolver;
btDiscreteDynamicsWorld* dynamicsWorld = new btDiscreteDynamicsWorld(dispatcher, overlappingPairCache, solver, collisionConfiguration);

Rapier:

let mut physics_world = rapier3d::dynamics::World::new();
let collider = ColliderBuilder::cuboid(0.5, 0.5, 0.5).build();
let rigid_body = RigidBodyBuilder::new_dynamic().translation(0.0, 10.0, 0.0).build();
physics_world.add_rigid_body(rigid_body);
physics_world.add_collider(collider, rigid_body_handle);

Pros of Box2D

• Mature and widely adopted physics engine with a large community and extensive documentation
• Lightweight and efficient, suitable for resource-constrained environments
• Supports a wide range of programming languages through bindings

Cons of Box2D

• Written in C++, which may not be ideal for all projects or developers
• Less frequent updates and slower development pace compared to Rapier
• Limited to 2D physics simulations

Code Comparison

Box2D (C++):

b2Vec2 gravity(0.0f, -10.0f);
b2World world(gravity);
b2BodyDef groundBodyDef;
b2Body* groundBody = world.CreateBody(&groundBodyDef);

Rapier (Rust):

let gravity = Vector2::new(0.0, -9.81);
let mut physics_world = World::new();
let collider = ColliderBuilder::cuboid(100.0, 0.1).build();
physics_world.add_collider(collider, BodyHandle::ground());

Both libraries provide similar functionality for creating a physics world and adding bodies. Box2D uses a more verbose C++ syntax, while Rapier leverages Rust's modern language features for a cleaner API. Rapier's code is generally more concise and type-safe, but Box2D's API may be more familiar to developers with C++ experience.

Pros of PhysX

• Mature and widely adopted in the game industry
• Extensive documentation and community support
• Optimized for NVIDIA GPUs, offering hardware acceleration

Cons of PhysX

• Closed-source and proprietary, limiting customization
• Primarily C++ focused, which may not suit all developers
• Can be complex to integrate and use for smaller projects

Code Comparison

PhysX (C++):

PxRigidDynamic* dynamicActor = physics.createRigidDynamic(PxTransform(0,0,0));
PxRigidStatic* staticActor = physics.createRigidStatic(PxTransform(0,0,0));
PxShape* shape = physics.createShape(PxSphereGeometry(1.0f), *material);
dynamicActor->attachShape(*shape);
scene->addActor(*dynamicActor);

Rapier (Rust):

let rigid_body = RigidBodyBuilder::dynamic()
    .translation(0.0, 0.0, 0.0)
    .build();
let collider = ColliderBuilder::ball(1.0).build();
world.add_rigid_body(rigid_body);
world.add_collider(collider, rigid_body_handle);

PhysX offers a more verbose API with explicit actor and shape creation, while Rapier provides a more concise, builder-pattern approach. PhysX's C++ implementation may be more familiar to game developers, whereas Rapier's Rust code emphasizes safety and modern language features.

Pros of LiquidFun

• Specialized in fluid and soft body simulation, offering unique features for game developers
• Backed by Google, potentially providing more resources and long-term support
• Includes a testbed for easy visualization and experimentation

Cons of LiquidFun

• Less active development and updates compared to Rapier
• Limited to 2D physics simulations
• C++ only, while Rapier supports multiple languages including Rust and JavaScript

Code Comparison

LiquidFun (C++):

b2World world(gravity);
b2BodyDef bodyDef;
b2Body* body = world.CreateBody(&bodyDef);
b2CircleShape circle;
body->CreateFixture(&circle, 1.0f);

Rapier (Rust):

let mut world = World::new();
let collider = ColliderBuilder::ball(0.5).build();
let rigid_body = RigidBodyBuilder::dynamic().build();
world.add_rigid_body(rigid_body);
world.add_collider(collider, rigid_body_handle);

Both libraries offer straightforward APIs for creating physics worlds and bodies. LiquidFun uses a more C-style approach with pointers, while Rapier leverages Rust's ownership model for a safer API. Rapier's code is generally more concise and type-safe compared to LiquidFun's C++ implementation.