Crossy Road with three.js

crossy-road-with-three-js.markdown

Crossy Road with three.js

An interactive tech demo inspired by Crossy Road using three.js where I put together a scene with an orthographic camera that follows the player, a few simplified 3D objects with some texture, lights and shadows, and a basic game logic that randomly generates a level that you can walk through.

A Pen by Hunor Marton Borbely on CodePen.

License.

index.html

<div id="counter">0</div>
    
<div id="controlls">
  <div>
    <button id="forward">↑</button>
    <button id="left">←</button>
    <button id="backward">↓</button>
    <button id="right">→</button>
  </div>
</div>

<div id="end">
  <button id="retry">Retry</button>
</div>

script.js

const counterDOM = document.getElementById('counter');  
const endDOM = document.getElementById('end');  

const scene = new THREE.Scene();

const distance = 500;
const camera = new THREE.OrthographicCamera( window.innerWidth/-2, window.innerWidth/2, window.innerHeight / 2, window.innerHeight / -2, 0.1, 10000 );

camera.rotation.x = 50*Math.PI/180;
camera.rotation.y = 20*Math.PI/180;
camera.rotation.z = 10*Math.PI/180;

const initialCameraPositionY = -Math.tan(camera.rotation.x)*distance;
const initialCameraPositionX = Math.tan(camera.rotation.y)*Math.sqrt(distance**2 + initialCameraPositionY**2);
camera.position.y = initialCameraPositionY;
camera.position.x = initialCameraPositionX;
camera.position.z = distance;

const zoom = 2;

const chickenSize = 15;

const positionWidth = 42;
const columns = 17;
const boardWidth = positionWidth*columns;

const stepTime = 200; // Miliseconds it takes for the chicken to take a step forward, backward, left or right

let lanes;
let currentLane;
let currentColumn;

let previousTimestamp;
let startMoving;
let moves;
let stepStartTimestamp;

const carFrontTexture = new Texture(40,80,[{x: 0, y: 10, w: 30, h: 60 }]);
const carBackTexture = new Texture(40,80,[{x: 10, y: 10, w: 30, h: 60 }]);
const carRightSideTexture = new Texture(110,40,[{x: 10, y: 0, w: 50, h: 30 }, {x: 70, y: 0, w: 30, h: 30 }]);
const carLeftSideTexture = new Texture(110,40,[{x: 10, y: 10, w: 50, h: 30 }, {x: 70, y: 10, w: 30, h: 30 }]);

const truckFrontTexture = new Texture(30,30,[{x: 15, y: 0, w: 10, h: 30 }]);
const truckRightSideTexture = new Texture(25,30,[{x: 0, y: 15, w: 10, h: 10 }]);
const truckLeftSideTexture = new Texture(25,30,[{x: 0, y: 5, w: 10, h: 10 }]);

const generateLanes = () => [-9,-8,-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9].map((index) => {
    const lane = new Lane(index);
    lane.mesh.position.y = index*positionWidth*zoom;
    scene.add( lane.mesh );
    return lane;
}).filter((lane) => lane.index >= 0);

const addLane = () => {
    const index = lanes.length;
    const lane = new Lane(index);
    lane.mesh.position.y = index*positionWidth*zoom;
    scene.add(lane.mesh);
    lanes.push(lane);
}

const chicken = new Chicken();
scene.add( chicken );

const laneTypes = ['car', 'truck', 'forest'];
const laneSpeeds = [2, 2.5, 3];
const vechicleColors = [0xa52523, 0xbdb638, 0x78b14b];
const threeHeights = [20,45,60];

const initaliseValues = () => {
    lanes = generateLanes()

    currentLane = 0;
    currentColumn = Math.floor(columns/2);

    previousTimestamp = null;

    startMoving = false;
    moves = [];
    stepStartTimestamp;

    chicken.position.x = 0;
    chicken.position.y = 0;

    camera.position.y = initialCameraPositionY;
    camera.position.x = initialCameraPositionX;
}

initaliseValues();

const renderer = new THREE.WebGLRenderer({
  alpha: true,
  antialias: true
});
renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );

hemiLight = new THREE.HemisphereLight(0xffffff, 0xffffff, 0.6);
scene.add(hemiLight)

dirLight = new THREE.DirectionalLight(0xffffff, 0.6);
dirLight.position.set(-100, -100, 200);
dirLight.castShadow = true;
scene.add(dirLight);

dirLight.shadow.mapSize.width = 2048;
dirLight.shadow.mapSize.height = 2048;
var d = 500;
dirLight.shadow.camera.left = - d;
dirLight.shadow.camera.right = d;
dirLight.shadow.camera.top = d;
dirLight.shadow.camera.bottom = - d;

// var helper = new THREE.CameraHelper( dirLight.shadow.camera );
// var helper = new THREE.CameraHelper( camera );
// scene.add(helper)

backLight = new THREE.DirectionalLight(0x000000, .4);
backLight.position.set(200, 200, 50);
backLight.castShadow = true;
scene.add(backLight)

function Texture(width, height, rects) {
    const canvas = document.createElement( "canvas" );
    canvas.width = width;
    canvas.height = height;
    const context = canvas.getContext( "2d" );
    context.fillStyle = "#ffffff";
    context.fillRect( 0, 0, width, height );
    context.fillStyle = "rgba(0,0,0,0.6)";  
    rects.forEach(rect => {
      context.fillRect(rect.x, rect.y, rect.w, rect.h);
    });
    return new THREE.CanvasTexture(canvas);
}

function Wheel() {
    const wheel = new THREE.Mesh( 
      new THREE.BoxBufferGeometry( 12*zoom, 33*zoom, 12*zoom ), 
      new THREE.MeshLambertMaterial( { color: 0x333333, flatShading: true } ) 
    );
    wheel.position.z = 6*zoom;
    return wheel;
}

function Car() {
  const car = new THREE.Group();
  const color = vechicleColors[Math.floor(Math.random() * vechicleColors.length)];
  
  const main = new THREE.Mesh(
    new THREE.BoxBufferGeometry( 60*zoom, 30*zoom, 15*zoom ), 
    new THREE.MeshPhongMaterial( { color, flatShading: true } )
  );
  main.position.z = 12*zoom;
  main.castShadow = true;
  main.receiveShadow = true;
  car.add(main)
  
  const cabin = new THREE.Mesh(
    new THREE.BoxBufferGeometry( 33*zoom, 24*zoom, 12*zoom ), 
    [
      new THREE.MeshPhongMaterial( { color: 0xcccccc, flatShading: true, map: carBackTexture } ),
      new THREE.MeshPhongMaterial( { color: 0xcccccc, flatShading: true, map: carFrontTexture } ),
      new THREE.MeshPhongMaterial( { color: 0xcccccc, flatShading: true, map: carRightSideTexture } ),
      new THREE.MeshPhongMaterial( { color: 0xcccccc, flatShading: true, map: carLeftSideTexture } ),
      new THREE.MeshPhongMaterial( { color: 0xcccccc, flatShading: true } ), // top
      new THREE.MeshPhongMaterial( { color: 0xcccccc, flatShading: true } ) // bottom
    ]
  );
  cabin.position.x = 6*zoom;
  cabin.position.z = 25.5*zoom;
  cabin.castShadow = true;
  cabin.receiveShadow = true;
  car.add( cabin );
  
  const frontWheel = new Wheel();
  frontWheel.position.x = -18*zoom;
  car.add( frontWheel );

  const backWheel = new Wheel();
  backWheel.position.x = 18*zoom;
  car.add( backWheel );

  car.castShadow = true;
  car.receiveShadow = false;
  
  return car;  
}

function Truck() {
    const truck = new THREE.Group();
    const color = vechicleColors[Math.floor(Math.random() * vechicleColors.length)];
    

    const base = new THREE.Mesh(
        new THREE.BoxBufferGeometry( 100*zoom, 25*zoom, 5*zoom ), 
        new THREE.MeshLambertMaterial( { color: 0xb4c6fc, flatShading: true } )
    );
    base.position.z = 10*zoom;
    truck.add(base)

    const cargo = new THREE.Mesh(
      new THREE.BoxBufferGeometry( 75*zoom, 35*zoom, 40*zoom ), 
      new THREE.MeshPhongMaterial( { color: 0xb4c6fc, flatShading: true } )
    );
    cargo.position.x = 15*zoom;
    cargo.position.z = 30*zoom;
    cargo.castShadow = true;
    cargo.receiveShadow = true;
    truck.add(cargo)

    const cabin = new THREE.Mesh(
      new THREE.BoxBufferGeometry( 25*zoom, 30*zoom, 30*zoom ), 
      [
        new THREE.MeshPhongMaterial( { color, flatShading: true } ), // back
        new THREE.MeshPhongMaterial( { color, flatShading: true, map: truckFrontTexture } ),
        new THREE.MeshPhongMaterial( { color, flatShading: true, map: truckRightSideTexture } ),
        new THREE.MeshPhongMaterial( { color, flatShading: true, map: truckLeftSideTexture } ),
        new THREE.MeshPhongMaterial( { color, flatShading: true } ), // top
        new THREE.MeshPhongMaterial( { color, flatShading: true } ) // bottom
      ]
    );
    cabin.position.x = -40*zoom;
    cabin.position.z = 20*zoom;
    cabin.castShadow = true;
    cabin.receiveShadow = true;
    truck.add( cabin );
    
    const frontWheel = new Wheel();
    frontWheel.position.x = -38*zoom;
    truck.add( frontWheel );
  
    const middleWheel = new Wheel();
    middleWheel.position.x = -10*zoom;
    truck.add( middleWheel );

    const backWheel = new Wheel();
    backWheel.position.x = 30*zoom;
    truck.add( backWheel );
    
    return truck;  
  }

function Three() {
    const three = new THREE.Group();
    
    const trunk = new THREE.Mesh(
      new THREE.BoxBufferGeometry( 15*zoom, 15*zoom, 20*zoom ), 
      new THREE.MeshPhongMaterial( { color: 0x4d2926, flatShading: true } )
    );
    trunk.position.z = 10*zoom;
    trunk.castShadow = true;
    trunk.receiveShadow = true;
    three.add(trunk);

    height = threeHeights[Math.floor(Math.random()*threeHeights.length)];

    const crown = new THREE.Mesh(
        new THREE.BoxBufferGeometry( 30*zoom, 30*zoom, height*zoom ), 
        new THREE.MeshLambertMaterial( { color: 0x7aa21d, flatShading: true } )
    );
    crown.position.z = (height/2+20)*zoom;
    crown.castShadow = true;
    crown.receiveShadow = false;
    three.add(crown);
    
    return three;  
}

function Chicken() {
    const chicken = new THREE.Group();
    
    const body = new THREE.Mesh(
      new THREE.BoxBufferGeometry( chickenSize*zoom, chickenSize*zoom, 20*zoom ), 
      new THREE.MeshPhongMaterial( { color: 0xffffff, flatShading: true } )
    );
    body.position.z = 10*zoom;
    body.castShadow = true;
    body.receiveShadow = true;
    chicken.add(body);

    const rowel = new THREE.Mesh(
        new THREE.BoxBufferGeometry( 2*zoom, 4*zoom, 2*zoom ), 
        new THREE.MeshLambertMaterial( { color: 0xF0619A, flatShading: true } )
    );
    rowel.position.z = 21*zoom;
    rowel.castShadow = true;
    rowel.receiveShadow = false;
    chicken.add(rowel);
    
    return chicken;  
}

function Road() {
    const road = new THREE.Group();

    const createSection = color => new THREE.Mesh(
        new THREE.PlaneBufferGeometry( boardWidth*zoom, positionWidth*zoom ), 
        new THREE.MeshPhongMaterial( { color } )
    );

    const middle = createSection(0x454A59);
    middle.receiveShadow = true;
    road.add(middle);

    const left = createSection(0x393D49);
    left.position.x = - boardWidth*zoom;
    road.add(left);

    const right = createSection(0x393D49);
    right.position.x = boardWidth*zoom;
    road.add(right);
    
    return road;
}

function Grass() {
    const grass = new THREE.Group();

    const createSection = color => new THREE.Mesh(
        new THREE.BoxBufferGeometry( boardWidth*zoom, positionWidth*zoom, 3*zoom ), 
        new THREE.MeshPhongMaterial( { color } )
    );

    const middle = createSection(0xbaf455);
    middle.receiveShadow = true;
    grass.add(middle);

    const left = createSection(0x99C846);
    left.position.x = - boardWidth*zoom;
    grass.add(left);

    const right = createSection(0x99C846);
    right.position.x = boardWidth*zoom;
    grass.add(right);

    grass.position.z = 1.5*zoom;
    return grass;
}

function Lane(index) {
    this.index = index;
    this.type = index <= 0 ? 'field' : laneTypes[Math.floor(Math.random()*laneTypes.length)];

    switch(this.type) {
        case 'field': {
            this.type = 'field';
            this.mesh = new Grass();
            break;
        }
        case 'forest': {
            this.mesh = new Grass();
            
            this.occupiedPositions = new Set();
            this.threes = [1,2,3,4].map(() => {
                const three = new Three();
                let position;
                do {
                    position = Math.floor(Math.random()*columns);
                }while(this.occupiedPositions.has(position))
                this.occupiedPositions.add(position);
                three.position.x = (position*positionWidth+positionWidth/2)*zoom-boardWidth*zoom/2;
                this.mesh.add( three );
                return three;
            })
            break;
        }
        case 'car' : {
            this.mesh = new Road();
            this.direction = Math.random() >= 0.5;
            
            const occupiedPositions = new Set();
            this.vechicles = [1,2,3].map(() => {
                const vechicle = new Car();
                let position;
                do {
                    position = Math.floor(Math.random()*columns/2);
                }while(occupiedPositions.has(position))
                occupiedPositions.add(position);
                vechicle.position.x = (position*positionWidth*2+positionWidth/2)*zoom-boardWidth*zoom/2;
                if(!this.direction) vechicle.rotation.z = Math.PI;
                this.mesh.add( vechicle );
                return vechicle;
            })

            this.speed = laneSpeeds[Math.floor(Math.random()*laneSpeeds.length)];
            break;
        }
        case 'truck' : {
            this.mesh = new Road();
            this.direction = Math.random() >= 0.5;
            
            const occupiedPositions = new Set();
            this.vechicles = [1,2].map(() => {
                const vechicle = new Truck();
                let position;
                do {
                    position = Math.floor(Math.random()*columns/3);
                }while(occupiedPositions.has(position))
                occupiedPositions.add(position);
                vechicle.position.x = (position*positionWidth*3+positionWidth/2)*zoom-boardWidth*zoom/2;
                if(!this.direction) vechicle.rotation.z = Math.PI;
                this.mesh.add( vechicle );
                return vechicle;
            })

            this.speed = laneSpeeds[Math.floor(Math.random()*laneSpeeds.length)];
            break;
        }
    }
}

document.querySelector("#retry").addEventListener("click", () => {
    lanes.forEach(lane => scene.remove( lane.mesh ));
    initaliseValues();
    endDOM.style.visibility = 'hidden';
});

document.getElementById('forward').addEventListener("click", () => move('forward'));

document.getElementById('backward').addEventListener("click", () => move('backward'));

document.getElementById('left').addEventListener("click", () => move('left'));

document.getElementById('right').addEventListener("click", () => move('right'));

window.addEventListener("keydown", event => {
    if (event.keyCode == '38') {
        // up arrow
        move('forward');
    }
    else if (event.keyCode == '40') {
        // down arrow
        move('backward');
    }
    else if (event.keyCode == '37') {
       // left arrow
       move('left');
    }
    else if (event.keyCode == '39') {
       // right arrow
       move('right');
    }
});

function move(direction) {
    const finalPositions = moves.reduce((position,move) => {
        if(move === 'forward') return {lane: position.lane+1, column: position.column};
        if(move === 'backward') return {lane: position.lane-1, column: position.column};
        if(move === 'left') return {lane: position.lane, column: position.column-1};
        if(move === 'right') return {lane: position.lane, column: position.column+1};
    }, {lane: currentLane, column: currentColumn})

    if (direction === 'forward') {
        if(lanes[finalPositions.lane+1].type === 'forest' && lanes[finalPositions.lane+1].occupiedPositions.has(finalPositions.column)) return;
        if(!stepStartTimestamp) startMoving = true;
        addLane();
    }
    else if (direction === 'backward') {
        if(finalPositions.lane === 0) return;
        if(lanes[finalPositions.lane-1].type === 'forest' && lanes[finalPositions.lane-1].occupiedPositions.has(finalPositions.column)) return;
        if(!stepStartTimestamp) startMoving = true;
    }
    else if (direction === 'left') {
       if(finalPositions.column === 0) return;
       if(lanes[finalPositions.lane].type === 'forest' && lanes[finalPositions.lane].occupiedPositions.has(finalPositions.column-1)) return;
       if(!stepStartTimestamp) startMoving = true;
    }
    else if (direction === 'right') {
       if(finalPositions.column === columns - 1 ) return;
       if(lanes[finalPositions.lane].type === 'forest' && lanes[finalPositions.lane].occupiedPositions.has(finalPositions.column+1)) return;
       if(!stepStartTimestamp) startMoving = true;
    }
    moves.push(direction);
}

function animate(timestamp) {
    requestAnimationFrame( animate );
    
    if(!previousTimestamp) previousTimestamp = timestamp;
    const delta = timestamp - previousTimestamp;
    previousTimestamp = timestamp;
  
    // Animate cars and trucks moving on the lane
    lanes.forEach(lane => {
        if(lane.type === 'car' || lane.type === 'truck') {
            const aBitBeforeTheBeginingOfLane = -boardWidth*zoom/2 - positionWidth*2*zoom;
            const aBitAfterTheEndOFLane = boardWidth*zoom/2 + positionWidth*2*zoom;
            lane.vechicles.forEach(vechicle => {
                if(lane.direction) {
                    vechicle.position.x = vechicle.position.x < aBitBeforeTheBeginingOfLane ? aBitAfterTheEndOFLane : vechicle.position.x -= lane.speed/16*delta;
                }else{
                    vechicle.position.x = vechicle.position.x > aBitAfterTheEndOFLane ? aBitBeforeTheBeginingOfLane : vechicle.position.x += lane.speed/16*delta;
                }
            });
        }
    });

    if(startMoving) {
        stepStartTimestamp = timestamp;
        startMoving = false;
    }

    if(stepStartTimestamp) {
        const moveDeltaTime = timestamp - stepStartTimestamp;
        const moveDeltaDistance = Math.min(moveDeltaTime/stepTime,1)*positionWidth*zoom;
        const jumpDeltaDistance = Math.sin(Math.min(moveDeltaTime/stepTime,1)*Math.PI)*8*zoom;
        switch(moves[0]) {
            case 'forward': {
                camera.position.y = initialCameraPositionY + currentLane*positionWidth*zoom + moveDeltaDistance;        
                chicken.position.y = currentLane*positionWidth*zoom + moveDeltaDistance; // initial chicken position is 0
                chicken.position.z = jumpDeltaDistance;
                break;
            }
            case 'backward': {
                camera.position.y = initialCameraPositionY + currentLane*positionWidth*zoom - moveDeltaDistance;
                chicken.position.y = currentLane*positionWidth*zoom - moveDeltaDistance;
                chicken.position.z = jumpDeltaDistance;
                break;
            }
            case 'left': {
                camera.position.x = initialCameraPositionX + (currentColumn*positionWidth+positionWidth/2)*zoom -boardWidth*zoom/2 - moveDeltaDistance;        
                chicken.position.x = (currentColumn*positionWidth+positionWidth/2)*zoom -boardWidth*zoom/2 - moveDeltaDistance; // initial chicken position is 0
                chicken.position.z = jumpDeltaDistance;
                break;
            }
            case 'right': {
                camera.position.x = initialCameraPositionX + (currentColumn*positionWidth+positionWidth/2)*zoom -boardWidth*zoom/2 + moveDeltaDistance;        
                chicken.position.x = (currentColumn*positionWidth+positionWidth/2)*zoom -boardWidth*zoom/2 + moveDeltaDistance; 
                chicken.position.z = jumpDeltaDistance;
                break;
            }
        }
        // Once a step has ended
        if(moveDeltaTime > stepTime) {
            switch(moves[0]) {
                case 'forward': {
                    currentLane++;
                    counterDOM.innerHTML = currentLane;    
                    break;
                }
                case 'backward': {
                    currentLane--;
                    counterDOM.innerHTML = currentLane;    
                    break;
                }
                case 'left': {
                    currentColumn--;
                    break;
                }
                case 'right': {
                    currentColumn++;
                    break;
                }
            }
            moves.shift();
            // If more steps are to be taken then restart counter otherwise stop stepping
            stepStartTimestamp = moves.length === 0 ? null : timestamp;
        }
    }

    // Hit test
    if(lanes[currentLane].type === 'car' || lanes[currentLane].type === 'truck') {
        const chickenMinX = chicken.position.x - chickenSize*zoom/2;
        const chickenMaxX = chicken.position.x + chickenSize*zoom/2;
        const vechicleLength = { car: 60, truck: 105}[lanes[currentLane].type]; 
        lanes[currentLane].vechicles.forEach(vechicle => {
            const carMinX = vechicle.position.x - vechicleLength*zoom/2;
            const carMaxX = vechicle.position.x + vechicleLength*zoom/2;
            if(chickenMaxX > carMinX && chickenMinX < carMaxX) {
                endDOM.style.visibility = 'visible';
            }
        });
    
    }
    renderer.render( scene, camera );	
}

requestAnimationFrame( animate );

scripts

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/99/three.min.js"></script>

style.css

@import url('https://fonts.googleapis.com/css?family=Press+Start+2P');

body {
  margin: 0;
  font-family: 'Press Start 2P', cursive;
  font-size: 2em;
  color: white;
}
button {
  outline: none;
  cursor: pointer;
}
#counter {
  position: absolute;
  top: 20px;
  right: 20px;
}
#end {
  position: absolute;
  min-width: 100%;
  min-height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  visibility: hidden;
}
#end button {
  background-color: red;
  padding: 20px 50px 20px 50px;
  font-family: inherit;
  font-size: inherit;
}
#controlls {
  position: absolute;
  min-width: 100%;
  min-height: 100%;
  display: flex;
  align-items: flex-end;
  justify-content: center;
}
#controlls div {
  margin-bottom: 20px;
  font-size: 0;
  max-width: 180px;
}
#controlls button {
  width: 50px;
  font-family: inherit;
  font-size: 30px;
  border: 3px solid white;
  color: white;
  background-color: transparent;
  margin: 5px;
}
#controlls button:first-of-type {
  width: 170px;
}