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This is a part ofNode3D project.

npm i -s bullet-raub

This addon is ABI-compatible across Node.js versions.There is no compilation duringnpm i.

Node.js addon providing a Bullet-driven physics API.

This library is a simplified interpretation ofBullet Physics.Only rigid bodies and DOF-6 constraint are supported.

Only rigid body primitives are supported. The API is simplified to just 3 classes:Scene, Body, Joint.Body can be static or dynamic and with different shapes. Joint is a DOF6 that you can set up inmany possible ways.

SeeTypeScript declarations for more details.

constscene=newScene();scene.gravity=[0,-9.8,0];constframe=()=>{scene.update();// <-- call update() to progress simulation!setTimeout(frame,15);};frame();

Thescene contains all bodies and joints. It is a high-level wrapper that initializes:

• btDefaultCollisionConfiguration
• btCollisionDispatcher
• btBroadphaseInterface
• btConstraintSolver
• btDynamicsWorld

Fromscene you can also run ray hits or traces. It should be possible to use many scenesin parallel.

const{ body}=scene.hit(start,end);

Herebody is whateverBody the ray hits first on its path. For subclasses ofBody,this will respect the dynamic type. I.e. forclass House extends Body {...} the expressionbody instanceof House will betrue.Seescene.hit andscene.trace in theexample.

constplane=newBody({ scene});// static boxplane.type='plane';// change shape to ("ground") planeconstbox=newBody({ scene});// 'box' is default typebox.pos=[0,100,0];// 100 meters abovebox.mass=1;// becomes dynamic

Passscene as a required constructor option. All bodies always exist within their parent scenes.

constjoint=newJoint();joint.minl=[0,1,0];joint.maxl=[0,1,0];joint.a=bodyA;joint.b=bodyB;

This will connectbodyA andbodyB and constrain their origins to always be 1 meter apart.You can also change the origin offsets, add rotation constraints and many other joint parameters.

Objects ofScene, Body, Joint - all have events for every property modification. E.g.as soon as you setscene.gravity=[0,0,0], and event will fire forscene.on('gravity', () => {...}).

You should callscene.update(dt: number = 0.0) in order for the scene to progress. Heredtis optional delta time in seconds. If not provided,dt will be calculated from internal timers.It is during this call toscene.update() the below'update' events will fire.

Objects ofBody will fire'update' events every tick while not sleeping:

body.on('update',(event)=>{event.pos;// position of body origin (usually center)event.quat;// rotation quaternionevent.vell;// linear velocity (where it goes)event.vela;// angular velocity (how much it spins)});

This is mostly designed to be fed into visualization APIs (such as Three.js), thereforea Quaternion is used to represent rotation. You may need linear/angular velocity forinterpolation, shading, networking, etc.

Objects ofJoint will fire'update' events every tick while not sleeping:

joint.on('update',(event)=>{event.posa;// current position of body Aevent.posb;// current position of body Bevent.broken;// boolean, is this joint broken});

Joints can be broken when overwhelmed with impulse. This is controlled byjoint.maximp -by default it's very high. But you can lower it so that, for instance, car wheels fall offupon extreme impact.