The basics of double jump concept in an endless runner game like Spring Ninja

Read all posts about "" game

Here we are talking about Spring Ninja prototype again.

What about adding a double jump feature to the final HTML5 prototype I showed you in this post.

First, let’s have a look at the result:

Click and hold to jump, and do the same thing while in the air to perform a double jump.

Let’s now have a look at the source code, with the new lines highlighted:

window.onload = function() {	
	var game = new Phaser.Game(640, 480, Phaser.CANVAS);
	var ninja;
	var ninjaGravity = 800;
	var ninjaJumpPower;    
	var score=0;
	var scoreText;
     var topScore;
     var powerBar;
     var powerTween;
     var placedPoles;
	var poleGroup; 
     var minPoleGap = 100;
     var maxPoleGap = 300; 
     var ninjaJumping;
     var ninjaFallingDown; 
	var jumps; 
	var maxExtraJumps = 1;   
     var play = function(game){}     
     play.prototype = {
		preload:function(){
			game.load.image("ninja", "ninja.png"); 
			game.load.image("pole", "pole.png");
               game.load.image("powerbar", "powerbar.png");
		},
		create:function(){
			ninjaJumping = false;
			ninjaFallingDown = false;
			score = 0;
			placedPoles = 0;
			jumps = 0;
			poleGroup = game.add.group();
			topScore = localStorage.getItem("topFlappyScore")==null?0:localStorage.getItem("topFlappyScore");
			scoreText = game.add.text(10,10,"-",{
				font:"bold 16px Arial"
			});
			updateScore();
			game.stage.backgroundColor = "#87CEEB";
			game.physics.startSystem(Phaser.Physics.ARCADE);
			ninja = game.add.sprite(80,0,"ninja");
			ninja.anchor.set(0.5);
			ninja.lastPole = 1;
			game.physics.arcade.enable(ninja);              
			ninja.body.gravity.y = ninjaGravity;
			addPole(80);
		},
		update:function(){
			game.physics.arcade.collide(ninja, poleGroup, checkLanding);
			if(ninja.y>game.height){
				die();
			}
		}
	}     
     game.state.add("Play",play);
     game.state.start("Play");
	function updateScore(){
		scoreText.text = "Score: "+score+"\nBest: "+topScore;	
	}     
	function prepareToJump(){
		if(ninja.body.velocity.y==0 || jumps<maxExtraJumps){
			jumps++;
	          powerBar = game.add.sprite(ninja.x,ninja.y-50,"powerbar");
	          powerBar.width = 0;
	          powerTween = game.add.tween(powerBar).to({
			   width:100
			}, 1000, "Linear",true); 
			game.input.onDown.remove(prepareToJump, this);
			game.input.onUp.add(jump, this);
          }        	
	}     
     function jump(){
          ninjaJumpPower= -powerBar.width*3-100
          powerBar.destroy();
          game.tweens.removeAll();
          ninja.body.velocity.y = ninjaJumpPower*2;
          ninjaJumping = true;
          powerTween.stop();
          game.input.onUp.remove(jump, this);
		if(jumps<maxExtraJumps){  
			game.input.onDown.add(prepareToJump, this);     
		}  
     }     
     function addNewPoles(){
     	var maxPoleX = 0;
		poleGroup.forEach(function(item) {
			maxPoleX = Math.max(item.x,maxPoleX)			
		});
		var nextPolePosition = maxPoleX + game.rnd.between(minPoleGap,maxPoleGap);
		addPole(nextPolePosition);			
	}
	function addPole(poleX){
		if(poleX<game.width*2){
			placedPoles++;
			var pole = new Pole(game,poleX,game.rnd.between(250,380));
			game.add.existing(pole);
	          pole.anchor.set(0.5,0);
			poleGroup.add(pole);
			var nextPolePosition = poleX + game.rnd.between(minPoleGap,maxPoleGap);
			addPole(nextPolePosition);
		}
	}	
	function die(){
		localStorage.setItem("topFlappyScore",Math.max(score,topScore));	
		game.state.start("Play");
	}
	function checkLanding(n,p){
		game.input.onDown.remove(prepareToJump, this);
		if(n.body.touching.down){
			var border = n.x-p.x
			if(Math.abs(border)>23){
				n.body.velocity.x=border*2;
				n.body.velocity.y=-200;	
			}
			else{
				jumps=0;          
               	game.input.onDown.add(prepareToJump, this);
			}
			var poleDiff = p.poleNumber-n.lastPole;
			if(poleDiff>0){
				score+= Math.pow(2,poleDiff);
				updateScore();	
				n.lastPole= p.poleNumber;
				ninja.x=80;
			}
			if(ninjaJumping){
               	ninjaJumping = false;    
          	}
		}
		else{
			ninjaFallingDown = true;
			poleGroup.forEach(function(item) {
				item.body.velocity.x = 0;			
			});
		}			
	}
	Pole = function (game, x, y) {
		Phaser.Sprite.call(this, game, x, y, "pole");
		game.physics.enable(this, Phaser.Physics.ARCADE);
          this.body.immovable = true;
          this.poleNumber = placedPoles;
	};
	Pole.prototype = Object.create(Phaser.Sprite.prototype);
	Pole.prototype.constructor = Pole;
	Pole.prototype.update = function() {
          if(ninjaJumping && !ninjaFallingDown){
               this.body.velocity.x = ninjaJumpPower;
          }
          else{
               this.body.velocity.x = 0
          }
		if(this.x<-this.width){
			this.destroy();
			addNewPoles();
		}
	}	
}

Since the game engine has been already built in the previous step, there are only a few new lines to see:

Line 17: defining jumps variable to keep track of consecutive jumps

Line 18: we’ll define another variable to make the script more universal: now you can decide how many extra jumps are allowed

Line 31: at the start of the game, jumps is set to zero

Line 60: we have to add another condition to let the player jump, that is we didn’t reach the extra jumps cap already

Line 61: now let’s increment jump by 1

Line 79: if we did not reach the maximum amount of extra jumps…

Line 80: … we add the listener to trigger mouse/touch input

Line 107: as soon as we touch the ground, re remove the listener

Line 114: if the player landed safely on the ground…

Line 115: reset jumps variable to zero

Line 116: add input listener once again

And we developed double jump. Download the full source code.

Get the most popular Phaser 3 book

Through 202 pages, 32 source code examples and an Android Studio project you will learn how to build cross platform HTML5 games and create a complete game along the way.

Get the book

215 GAME PROTOTYPES EXPLAINED WITH SOURCE CODE
// 1+2=3
// 100 rounds
// 10000000
// 2 Cars
// 2048
// A Blocky Christmas
// A Jumping Block
// A Life of Logic
// Angry Birds
// Angry Birds Space
// Artillery
// Astro-PANIC!
// Avoider
// Back to Square One
// Ball Game
// Ball vs Ball
// Ball: Revamped
// Balloon Invasion
// BallPusher
// Ballz
// Bar Balance
// Bejeweled
// Biggification
// Block it
// Blockage
// Bloons
// Boids
// Bombuzal
// Boom Dots
// Bouncing Ball
// Bouncing Ball 2
// Bouncy Light
// BoxHead
// Breakout
// Bricks
// Bubble Chaos
// Bubbles 2
// Card Game
// Castle Ramble
// Chronotron
// Circle Chain
// Circle Path
// Circle Race
// Circular endless runner
// Cirplosion
// CLOCKS - The Game
// Color Hit
// Color Jump
// ColorFill
// Columns
// Concentration
// Crossy Road
// Crush the Castle
// Cube Jump
// CubesOut
// Dash N Blast
// Dashy Panda
// Deflection
// Diamond Digger Saga
// Don't touch the spikes
// Dots
// Down The Mountain
// Drag and Match
// Draw Game
// Drop Wizard
// DROP'd
// Dudeski
// Dungeon Raid
// Educational Game
// Elasticity
// Endless Runner
// Erase Box
// Eskiv
// Farm Heroes Saga
// Filler
// Flappy Bird
// Fling
// Flipping Legend
// Floaty Light
// Fuse Ballz
// GearTaker
// Gem Sweeper
// Globe
// Goat Rider
// Gold Miner
// Grindstone
// GuessNext
// Helicopter
// Hero Emblems
// Hero Slide
// Hexagonal Tiles
// HookPod
// Hop Hop Hop Underwater
// Horizontal Endless Runner
// Hundreds
// Hungry Hero
// Hurry it's Christmas
// InkTd
// Iromeku
// Jet Set Willy
// Jigsaw Game
// Knife Hit
// Knightfall
// Legends of Runeterra
// Lep's World
// Line Rider
// Lumines
// Magick
// MagOrMin
// Mass Attack
// Math Game
// Maze
// Meeblings
// Memdot
// Metro Siberia Underground
// Mike Dangers
// Mikey Hooks
// Nano War
// Nodes
// o:anquan
// One Button Game
// One Tap RPG
// Ononmin
// Pacco
// Perfect Square!
// Perfectionism
// Phyballs
// Pixel Purge
// PixelField
// Planet Revenge
// Plants Vs Zombies
// Platform
// Platform game
// Plus+Plus
// Pocket Snap
// Poker
// Pool
// Pop the Lock
// Pop to Save
// Poux
// Pudi
// Pumpkin Story
// Puppet Bird
// Pyramids of Ra
// qomp
// Quick Switch
// Racing
// Radical
// Rebuild Chile
// Renju
// Rise Above
// Risky Road
// Roguelike
// Roly Poly
// Run Around
// Rush Hour
// SameGame
// SamePhysics
// Save the Totem
// Security
// Serious Scramblers
// Shrink it
// Sling
// Slingy
// Snowflakes
// Sokoban
// Space Checkers
// Space is Key
// Spellfall
// Spinny Gun
// Splitter
// Spring Ninja
// Sproing
// Stabilize!
// Stack
// Stairs
// Stick Hero
// String Avoider
// Stringy
// Sudoku
// Super Mario Bros
// Surfingers
// Survival Horror
// Talesworth Adventure
// Tetris
// The Impossible Line
// The Moops - Combos of Joy
// The Next Arrow
// Threes
// Tic Tac Toe
// Timberman
// Tiny Wings
// Tipsy Tower
// Toony
// Totem Destroyer
// Tower Defense
// Trick Shot
// Tunnelball
// Turn
// Turnellio
// TwinSpin
// vvvvvv
// Warp Shift
// Way of an Idea
// Whack a Creep
// Wheel of Fortune
// Where's my Water
// Wish Upon a Star
// Word Game
// Wordle
// Worms
// Yanga
// Yeah Bunny
// Zhed
// zNumbers