LiquidFun Rust

Rust bindings for LiquidFun.

• Model LiquidFun C++ API as closely as possible in idiomatic Rust.
• Documentation for C++ API should be usable for Rust API.
• Document places where Rust API varries from C++ API.

Usage

First, add the following to your Cargo.toml:

[dependencies]

liquidfun = "*"

Next, add this to your crate root:

extern crate liquidfun;

Example

extern crate liquidfun;

use liquidfun::box2d::common::math::*;
use liquidfun::box2d::dynamics::world::*;

#[test]
fn hello_world() {

	// Define the gravity vector.
	let gravity = Vec2::new(0.0, -10.0);

	// Construct a world object, which will hold and simulate the rigid bodies.
	let mut world = World::new(&gravity);
	assert_eq!(gravity, world.get_gravity());

}

Status

The LiquidFun Hello World example compiles and runs. More bindings will be added as needed by projects that depend on LiquidFun Rust.

User Data

Some objects in LiquidFun allow you to attach your own data to them. These are bound as usize. You can store raw pointers to your data there.

	ground_body_def.user_data = &Vec2::new(6.0, 66.0) as *const Vec2 as usize;

Passing structs by value from C++ to Rust

• make a new typedef struct with same name as C++ struct but with c_ prefix
• add just the data parts from the C++ struct, make sure both struct members have the same order

// C++
struct b2Vec2 {
	b2Vec2() {}
	...
	float32 x, y;
};

// new C struct
typedef struct c_b2Vec2 { float32 x, y; } c_b2Vec2;

• make a casting function
• cast C++ struct to new C struct and pass back to rust

c_b2Vec2* cast(b2Vec2* v) {
    return reinterpret_cast<c_b2Vec2*>(v);
}

c_b2Vec2 sendStructFromCppToRustByValue() {
	b2Vec2 tmp;
    return *cast(&tmp);
}

References

LiquidFun Programmer's Guide LiquidFun API Documentation

Thank You

Erin Catto for Box2D

Google for LiquidFun

Nicolas Silva for box2d.rs