Echo is a 2D Physics library written in Haxe.
It focuses on maintaining a simple API that is easy to integrate into any engine/framework (Heaps, OpenFL, Kha, etc). All Echo needs is an update loop and its ready to go!
Try the Samples here!
- Semi-implicit euler integration physics
- SAT-powered collision detection
- Quadtree for broadphase collision querying
- Collision listeners to provide collision callbacks
- Extendable debug drawing
Echo requires Haxe 4 to run.
Install the library from haxelib:
haxelib install echo
Alternatively the library can be installed from github:
haxelib git echo https://github.com/AustinEast/echo.git
Then include the library in your project's .hxml:
-lib echo
For OpenFL users, add this into your Project.xml instead:
<haxelib name="echo" />
The Echo Class holds helpful utility methods to help streamline the creation and management of Physics Simulations. It is recommended import this class like so:
using echo.Echo;
A World is an Object representing the state of a Physics simulation and it configurations.
A Body is an Object representing a Physical Body in a World. A Body has a position, velocity, mass, an optional collider shape, and many other properties that are used in a World simulation.
A Body's collider are represented by different Shapes. Available Shapes:
- Rectangle
- Circle
- Capsule (Coming Soon)
- Polygon (Coming Soon)
Groups are collections of Bodys. These can be used for grouping collisions.
Listeners keep track of collisions between Bodies and Groups, enacting callbacks and physics responses, depending on their configurations.
// `using` echo.Echo is prefered over importing it, as it adds in some useful extension methods
using echo.Echo;
class Main {
static function main() {
// Create a World to hold all the Physics Bodies
// Worlds, Bodies, and Listeners are all created with optional configuration objects.
// This makes it easy to construct object configurations, reuse them, and even easily load them from JSON!
var world = Echo.start({
width: 64, // Affects the bounds for collision checks.
height: 64, // Affects the bounds for collision checks.
gravity_y: 5, // Force of Gravity on the Y axis. Also available for the X axis.
iterations: 2 // Sets the number of iterations each time the World steps.
});
// Create a Body with a Circle Collider and add it to the World
world.make({
shape: {
type: CIRCLE,
radius: 16
}
});
// Create a Body with a Rectangle collider and add it to the World
// This Body will have a Mass of zero, rendering it as unmovable
// This is useful for things like platforms or walls.
world.make({
mass: 0, // Setting this to zero makes the body unmovable by forces and collisions
y: 48, // Set the object's Y position below the Circle, so that gravity makes them collide
shape: {
type: RECT,
width: 10,
height: 10
}
});
// Create a basic listener.
// Calling this with no parameters will cause every object to collide against one another
world.listen();
// Set up a Timer to act as an update loop
new haxe.Timer(16).run = () -> {
// Step the World's Physics Simulation forward
world.step(16 / 1000);
// Log the World State in the Console
echo.util.Debug.log(world);
}
}
}