therohans / dapao

A lightweight 3D physics engine written in Typescript.

大炮 (Dàpào)

Lightweight 3D Physics for the Web and Beyond

Dapao is just a Typescript port of the cannon.js library with some added tests.

Project Goals

I am porting this to Typescript so I can use it within my own game engine (which is in Typescript). While the cannon.js version works perfectly well, I want to have better integration with my engine (tree shaking, etc), and I eventually want to be able to compile this to webassembly or maybe even native - things Javascript can't do at the moment.

Using the library

If you want to use the library, you can either reference this repo directly from within your webpack config:

...
"dependencies": {
  "dapao": "https://github.com/TheRohans/dapao.git#master",
  "document-register-element": "^1.7.0"
  ...
},
...

Or clone the repo and reference it from the local file system:

...
"dependencies": {
  "dapao": "file:../dapao",
  "document-register-element": "^1.7.0"
  ...
},
...

Contributing

1. Clone this repository
2. Install node.js
3. Run npm install to install all of the dependencies
4. Run npm run build to build DaPao

Example

For deeper examples, I recommend you checkout the cannon.js project (cannon.js), but here is a very basic example:

The sample code below creates a sphere on a plane, steps the simulation, and prints the sphere simulation to the console. Note that DaPao (and Cannon.js) uses SI units (metre, kilogram, second, etc.).

import * as DaPao from 'dapao';

// Setup our world
var world = new DaPao.World();
world.gravity.set(0, 0, -9.82); // m/s²

// Create a sphere
var radius = 1; // m
var sphereBody = new DaPao.Body({
   mass: 5, // kg
   position: new DaPao.Vec3(0, 0, 10), // m
   shape: new DaPao.Sphere(radius)
});
world.addBody(sphereBody);

// Create a plane
var groundBody = new DaPao.Body({
    mass: 0 // mass == 0 makes the body static
});
var groundShape = new DaPao.Plane();
groundBody.addShape(groundShape);
world.addBody(groundBody);

var fixedTimeStep = 1.0 / 60.0; // seconds
var maxSubSteps = 3;

// Start the simulation loop
var lastTime;
(function simloop(time){
  requestAnimationFrame(simloop);
  if(lastTime !== undefined){
     var dt = (time - lastTime) / 1000;
     world.step(fixedTimeStep, dt, maxSubSteps);
  }
  console.log("Sphere z position: " + sphereBody.position.z);
  lastTime = time;
})();

Features

• Rigid body dynamics
• Discrete collision detection
• Contacts, friction and restitution
• Collision filters
• Body sleeping
• Various shapes and collision algorithms (see table below)

	Sphere	Plane	Box	Convex	Particle	Heightfield	Trimesh
Sphere	Yes	Yes	Yes	Yes	NT	TD	TD
Plane	-	-	Yes	Yes	NT	-	TD
Box	-	-	Yes	BU	NT	TD	TD
Cylinder	-	-	NT	NT	NT	TD	TD
Convex	-	-	-	BU	NT	TD	TD
Particle	-	-	-	-	-	TD	TD
Heightfield	-	-	-	-	-	-	TD
Trimesh	-	-	-	-	-	-	-

• NT = Not tested, but code exists. Feedback welcome.
• BU = Buggy
• TD = Todo