let skyAngle = 0

let ufoElevation = -100

let descentSpeed = 2

let gravity = -0.0068

let ufoAngle = 0

const GROUND_ELEVATION = 190

​

let trees = [{

    x: 300,

    z: -340

  },

  {

    x: -200,

    z: 200

  },

  {

    x: 200,

    z: 200

  }, {

    x: -300,

    z: -340

  }

]

​

let dirtTexture

let alienTexture

let moonTexture

let starTexture

let barkTexture

let leafTexture

​

function preload() {

  dirtTexture = loadImage("dirt.jpg")

  alienTexture = loadImage("alien.jpg")

  moonTexture = loadImage("moontexture.png")

  starTexture = loadImage("startexture.jpg")

  barkTexture = loadImage("bark.jpg")

  leafTexture = loadImage("leaf.jpg")

}

​

function setup() {

  createCanvas(700, 700, WEBGL)

}

​

function draw() {

  setupScene()

  drawStars()

  drawMoon()

  drawUfo()

  drawGround()

  drawTrees()

  animateUfo()

  rotateSky()

}

​

function rotateSky() {

  skyAngle += 0.001

}

​

function setupScene() {

  background('midnightblue')

  noStroke()

  directionalLight(255, 255, 255, -2, 1, -1)

  pointLight(255, 255, 255, 300, 70, 0)

}

​

function drawGround() {

  push()

  texture(dirtTexture)

  spotLight(255, 255, 255, 0, ufoElevation, ufoZ, 0, 1, 0, Math.PI / 6, 5)

  translate(0, 200, 0)

  rotateX(Math.PI / 2)

  plane(width * 2, width)

  pop()

}

​

function drawTrees(x, z) {

  for (let tree of trees) {

    push()

    translate(tree.x, 120, tree.z)

    texture(leafTexture)

    sphere(40, 16, 4)

    translate(0, 50, 0)

    texture(barkTexture)

    cylinder(10, 60)

    pop()

  }

}

​

function drawStars() {

  push()

  texture(starTexture)

  translate(0, 300, -500)

  rotateZ(skyAngle)

  plane(width * 3.5)

  pop()

}

​

function drawMoon() {

  push()

  rotateZ(skyAngle)

  texture(moonTexture)

  translate(-400, -200, -390)

  sphere(40)

  pop()

}

​

function drawUfo() {

  push()

  translate(0, ufoElevation, ufoZ)

  rotateY(ufoAngle)

  specularMaterial('gray')

  shininess(10)

  ellipsoid(100, 15, 100)

  translate(0, -14, 0)

  drawAlien()

  fill(60, 90, 200, 100)

  ellipsoid(50, 20, 50)

  translate(0, 24, 0)

  emissiveMaterial('white')

  sphere(10)

  pop()

}

​

function drawAlien() {

  push()

  rotateY(2)

  texture(alienTexture)

  translate(15, -6, 0)

  ellipsoid(5, 8, 5)

  pop()

}

​

function animateUfo() {

  ufoZ < 0 ? ufoZ += 1 : ufoLanding()

}

​

function ufoLanding() {

  descentSpeed += gravity

  ufoElevation += descentSpeed

  ufoAngle += 0.1

  if (ufoElevation > GROUND_ELEVATION) {

    noLoop()

  }

}