planck-js/example/BasicSliderCrank.ts

2D JavaScript/TypeScript physics engine for cross-platform HTML5 game development

/*
 * Copyright (c) Erin Catto
 * Licensed under the MIT license
 */

// A basic slider crank created for GDC tutorial: Understanding Constraints

import { World, Box, RevoluteJoint, PrismaticJoint, Testbed } from "planck";

const world = new World({
  gravity: { x: 0, y: -10 },
});

const testbed = Testbed.mount();
testbed.y = -15;
testbed.start(world);

const ground = world.createBody({
  type: "static",
  position: { x: 0.0, y: 17.0 },
});

// Define crank.
const crank = world.createBody({
  type: "dynamic",
  position: { x: -8.0, y: 20.0 },
});
crank.createFixture({
  shape: new Box(4.0, 1.0),
  density: 2.0,
});
world.createJoint(new RevoluteJoint({}, ground, crank, { x: -12.0, y: 20.0 }));

// Define connecting rod
const rod = world.createBody({
  type: "dynamic",
  position: { x: 4.0, y: 20.0 },
});
rod.createFixture({
  shape: new Box(8.0, 1.0),
  density: 2.0,
});
world.createJoint(new RevoluteJoint({}, crank, rod, { x: -4.0, y: 20.0 }));

// Define piston
const piston = world.createBody({
  type: "dynamic",
  position: { x: 12.0, y: 20.0 },
  fixedRotation: true,
});
piston.createFixture({
  shape: new Box(3.0, 3.0),
  density: 2.0,
});
world.createJoint(new RevoluteJoint({}, rod, piston, { x: 12.0, y: 20.0 }));
world.createJoint(new PrismaticJoint({}, ground, piston, { x: 12.0, y: 17.0 }, { x: 1.0, y: 0.0 }));