/*
Three.js + Cannon.js video tutorial explaining the source code
Youtube: https://youtu.be/hBiGFpBle7E
SkillShare: https://skl.sh/3uREVvq
In the tutorial, we go through the source code of this game. We cover, how to set up a Three.js scene with box objects, how to add lights, how to set up the camera, how to add animation and event handlers, and finally, we add physics simulation with Cannon.js.
Comparing to the tutorial this version has some extra features:
- autopilot mode before the game starts
- introduction and result screens
- score indicator showing the level of layers added
- you can also control the game with touch events and by pressing the space key
- you can reset the game
- the game stops once a block went over the stack
- once the game failed the last block falls down
- the game reacts to window resizing
Check out my YouTube channel for other game tutorials: https://www.youtube.com/channel/UCxhgW0Q5XLvIoXHAfQXg9oQ
*/
window.focus(); // Capture keys right away (by default focus is on editor)
let camera, scene, renderer; // ThreeJS globals
let world; // CannonJs world
let lastTime; // Last timestamp of animation
let stack; // Parts that stay solid on top of each other
let overhangs; // Overhanging parts that fall down
const boxHeight = 1; // Height of each layer
const originalBoxSize = 3; // Original width and height of a box
let autopilot;
let gameEnded;
let robotPrecision; // Determines how precise the game is on autopilot
const scoreElement = document.getElementById("score");
const instructionsElement = document.getElementById("instructions");
const resultsElement = document.getElementById("results");
init();
// Determines how precise the game is on autopilot
function setRobotPrecision() {
robotPrecision = Math.random() * 1 - 0.5;
}
function init() {
autopilot = true;
gameEnded = false;
lastTime = 0;
stack = [];
overhangs = [];
setRobotPrecision();
// Initialize CannonJS
world = new CANNON.World();
world.gravity.set(0, -10, 0); // Gravity pulls things down
world.broadphase = new CANNON.NaiveBroadphase();
world.solver.iterations = 40;
// Initialize ThreeJs
const aspect = window.innerWidth / window.innerHeight;
const width = 10;
const height = width / aspect;
camera = new THREE.OrthographicCamera(
width / -2, // left
width / 2, // right
height / 2, // top
height / -2, // bottom
0, // near plane
100 // far plane
);
/*
// If you want to use perspective camera instead, uncomment these lines
camera = new THREE.PerspectiveCamera(
45, // field of view
aspect, // aspect ratio
1, // near plane
100 // far plane
);
*/
camera.position.set(4, 4, 4);
camera.lookAt(0, 0, 0);
scene = new THREE.Scene();
// Foundation
addLayer(0, 0, originalBoxSize, originalBoxSize);
// First layer
addLayer(-10, 0, originalBoxSize, originalBoxSize, "x");
// Set up lights
const ambientLight = new THREE.AmbientLight(0xffffff, 0.6);
scene.add(ambientLight);
const dirLight = new THREE.DirectionalLight(0xffffff, 0.6);
dirLight.position.set(10, 20, 0);
scene.add(dirLight);
// Set up renderer
renderer = new THREE.WebGLRenderer({ antialias: true });
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.setAnimationLoop(animation);
document.body.appendChild(renderer.domElement);
}
function startGame() {
autopilot = false;
gameEnded = false;
lastTime = 0;
stack = [];
overhangs = [];
if (instructionsElement) instructionsElement.style.display = "none";
if (resultsElement) resultsElement.style.display = "none";
if (scoreElement) scoreElement.innerText = 0;
if (world) {
// Remove every object from world
while (world.bodies.length > 0) {
world.remove(world.bodies[0]);
}
}
if (scene) {
// Remove every Mesh from the scene
while (scene.children.find((c) => c.type == "Mesh")) {
const mesh = scene.children.find((c) => c.type == "Mesh");
scene.remove(mesh);
}
// Foundation
addLayer(0, 0, originalBoxSize, originalBoxSize);
// First layer
addLayer(-10, 0, originalBoxSize, originalBoxSize, "x");
}
if (camera) {
// Reset camera positions
camera.position.set(4, 4, 4);
camera.lookAt(0, 0, 0);
}
}
function addLayer(x, z, width, depth, direction) {
const y = boxHeight * stack.length; // Add the new box one layer higher
const layer = generateBox(x, y, z, width, depth, false);
layer.direction = direction;
stack.push(layer);
}
function addOverhang(x, z, width, depth) {
const y = boxHeight * (stack.length - 1); // Add the new box one the same layer
const overhang = generateBox(x, y, z, width, depth, true);
overhangs.push(overhang);
}
function generateBox(x, y, z, width, depth, falls) {
// ThreeJS
const geometry = new THREE.BoxGeometry(width, boxHeight, depth);
const color = new THREE.Color(`hsl(${30 + stack.length * 4}, 100%, 50%)`);
const material = new THREE.MeshLambertMaterial({ color });
const mesh = new THREE.Mesh(geometry, material);
mesh.position.set(x, y, z);
scene.add(mesh);
// CannonJS
const shape = new CANNON.Box(
new CANNON.Vec3(width / 2, boxHeight / 2, depth / 2)
);
let mass = falls ? 5 : 0; // If it shouldn't fall then setting the mass to zero will keep it stationary
mass *= width / originalBoxSize; // Reduce mass proportionately by size
mass *= depth / originalBoxSize; // Reduce mass proportionately by size
const body = new CANNON.Body({ mass, shape });
body.position.set(x, y, z);
world.addBody(body);
return {
threejs: mesh,
cannonjs: body,
width,
depth
};
}
function cutBox(topLayer, overlap, size, delta) {
const direction = topLayer.direction;
const newWidth = direction == "x" ? overlap : topLayer.width;
const newDepth = direction == "z" ? overlap : topLayer.depth;
// Update metadata
topLayer.width = newWidth;
topLayer.depth = newDepth;
// Update ThreeJS model
topLayer.threejs.scale[direction] = overlap / size;
topLayer.threejs.position[direction] -= delta / 2;
// Update CannonJS model
topLayer.cannonjs.position[direction] -= delta / 2;
// Replace shape to a smaller one (in CannonJS you can't simply just scale a shape)
const shape = new CANNON.Box(
new CANNON.Vec3(newWidth / 2, boxHeight / 2, newDepth / 2)
);
topLayer.cannonjs.shapes = [];
topLayer.cannonjs.addShape(shape);
}
window.addEventListener("mousedown", eventHandler);
window.addEventListener("touchstart", eventHandler);
window.addEventListener("keydown", function (event) {
if (event.key == " ") {
event.preventDefault();
eventHandler();
return;
}
if (event.key == "R" || event.key == "r") {
event.preventDefault();
startGame();
return;
}
});
function eventHandler() {
if (autopilot) startGame();
else splitBlockAndAddNextOneIfOverlaps();
}
function splitBlockAndAddNextOneIfOverlaps() {
if (gameEnded) return;
const topLayer = stack[stack.length - 1];
const previousLayer = stack[stack.length - 2];
const direction = topLayer.direction;
const size = direction == "x" ? topLayer.width : topLayer.depth;
const delta =
topLayer.threejs.position[direction] -
previousLayer.threejs.position[direction];
const overhangSize = Math.abs(delta);
const overlap = size - overhangSize;
if (overlap > 0) {
cutBox(topLayer, overlap, size, delta);
// Overhang
const overhangShift = (overlap / 2 + overhangSize / 2) * Math.sign(delta);
const overhangX =
direction == "x"
? topLayer.threejs.position.x + overhangShift
: topLayer.threejs.position.x;
const overhangZ =
direction == "z"
? topLayer.threejs.position.z + overhangShift
: topLayer.threejs.position.z;
const overhangWidth = direction == "x" ? overhangSize : topLayer.width;
const overhangDepth = direction == "z" ? overhangSize : topLayer.depth;
addOverhang(overhangX, overhangZ, overhangWidth, overhangDepth);
// Next layer
const nextX = direction == "x" ? topLayer.threejs.position.x : -10;
const nextZ = direction == "z" ? topLayer.threejs.position.z : -10;
const newWidth = topLayer.width; // New layer has the same size as the cut top layer
const newDepth = topLayer.depth; // New layer has the same size as the cut top layer
const nextDirection = direction == "x" ? "z" : "x";
if (scoreElement) scoreElement.innerText = stack.length - 1;
addLayer(nextX, nextZ, newWidth, newDepth, nextDirection);
} else {
missedTheSpot();
}
}
function missedTheSpot() {
const topLayer = stack[stack.length - 1];
// Turn to top layer into an overhang and let it fall down
addOverhang(
topLayer.threejs.position.x,
topLayer.threejs.position.z,
topLayer.width,
topLayer.depth
);
world.remove(topLayer.cannonjs);
scene.remove(topLayer.threejs);
gameEnded = true;
if (resultsElement && !autopilot) resultsElement.style.display = "flex";
}
function animation(time) {
if (lastTime) {
const timePassed = time - lastTime;
const speed = 0.008;
const topLayer = stack[stack.length - 1];
const previousLayer = stack[stack.length - 2];
// The top level box should move if the game has not ended AND
// it's either NOT in autopilot or it is in autopilot and the box did not yet reach the robot position
const boxShouldMove =
!gameEnded &&
(!autopilot ||
(autopilot &&
topLayer.threejs.position[topLayer.direction] <
previousLayer.threejs.position[topLayer.direction] +
robotPrecision));
if (boxShouldMove) {
// Keep the position visible on UI and the position in the model in sync
topLayer.threejs.position[topLayer.direction] += speed * timePassed;
topLayer.cannonjs.position[topLayer.direction] += speed * timePassed;
// If the box went beyond the stack then show up the fail screen
if (topLayer.threejs.position[topLayer.direction] > 10) {
missedTheSpot();
}
} else {
// If it shouldn't move then is it because the autopilot reached the correct position?
// Because if so then next level is coming
if (autopilot) {
splitBlockAndAddNextOneIfOverlaps();
setRobotPrecision();
}
}
// 4 is the initial camera height
if (camera.position.y < boxHeight * (stack.length - 2) + 4) {
camera.position.y += speed * timePassed;
}
updatePhysics(timePassed);
renderer.render(scene, camera);
}
lastTime = time;
}
function updatePhysics(timePassed) {
world.step(timePassed / 1000); // Step the physics world
// Copy coordinates from Cannon.js to Three.js
overhangs.forEach((element) => {
element.threejs.position.copy(element.cannonjs.position);
element.threejs.quaternion.copy(element.cannonjs.quaternion);
});
}
window.addEventListener("resize", () => {
// Adjust camera
console.log("resize", window.innerWidth, window.innerHeight);
const aspect = window.innerWidth / window.innerHeight;
const width = 10;
const height = width / aspect;
camera.top = height / 2;
camera.bottom = height / -2;
// Reset renderer
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.render(scene, camera);
});