box2d

osl/box2d provides worlds, bodies, and box, circle, or polygon fixtures using a pure-Go engine.

import "std:box2d"

world = box2d.newWorld({x: 0, y: 10})
ground = world.createBody({type: "static", x: 0, y: 10})
void ground.addBox(20, 1, {friction: 0.4})

player = world.createBody({type: "dynamic", x: 0, y: 0})
void player.addBox(1, 1, {density: 1, friction: 0.4})

loop 120 (
  void world.step(1.0 / 60)
)

log player.position()

Package

• box2d.vec(x, y) creates a vector object.

• box2d.newWorld(gravity) creates a world. Gravity accepts {x, y} or [x, y].

World

• createBody(options) creates a static, kinematic, or dynamic body.

• step(dt, velocityIterations?, positionIterations?) advances the simulation. Defaults are 8 and 3.

• gravity() and setGravity(vector) read or change gravity.

• bodyCount() and contactCount() report world state.

• destroyBody(body) removes one body. destroy() invalidates the world.

Body options include position, x, y, angle, velocity, angularVelocity, damping, allowSleep, awake, fixedRotation, bullet, active, and gravityScale.

Body

• addBox(width, height, options), addCircle(radius, options), and addPolygon(points, options) add fixtures.

• Fixture options include density, friction, restitution, and sensor.

• position(), angle(), linearVelocity(), mass(), bodyType(), and awake() inspect state.

• setTransform(position, angle) and setLinearVelocity(vector) change state.

• applyForce(vector) and applyImpulse(vector) affect dynamic bodies.

Destroyed body handles return safe zero values or false instead of accessing invalid engine state.