let GROUND_SPRITE_WIDTH = 50

let GROUND_SPRITE_HEIGHT = 50

let numGroundSprites

let GRAVITY = 2

let JUMP =-5

let player

​

function setup() {

  createCanvas(400, 400);

  groundSprites = new Group()

  numGroundSprites = width/GROUND_SPRITE_WIDTH+1

  for(n = 0 ; n < numGroundSprites; n ++){

  let groundSprite = createSprite(

  n*50,

  height - 25,

  GROUND_SPRITE_WIDTH,

  GROUND_SPRITE_HEIGHT

  )

  groundSprites.add(groundSprite)

  }  

  player = createSprite(100, height- 75, 50, 50)

}

function draw() {

  background(150,200,250)

   player.velocity.y=+GRAVITY

  if (keyDown(UP_ARROW)) {

  player.velocity.y=JUMP

  }

  if (groundSprites.overlap(player)){

  player.position.y=height-50-player.height/2

      }

  player.position.x = player.position.x+5

  camera.position.x = player.position.x

  let firstGroundSprite = groundSprites[0]

  if (firstGroundSprite.position.x<=camera.position.x-(width/2+firstGroundSprite.width/2)){

  groundSprites.remove(firstGroundSprite)

  firstGroundSprite.position.x=firstGroundSprite.position.x+numGroundSprites*firstGroundSprite.width

    groundSprites.add(firstGroundSprite)

  }

  drawSprites()

}