Talking about Game development, HTML5, Javascript and Phaser.
One nice feature I love to find in platform games is wall jump. It’s the ability to jump, hit a wall and jump again on the opposite direction. This ability is often used to let the player climb levels, jumping from wall to wall. Thanks to Phaser and ARCADE physics, we can do it in just a few lines. First, let’s have a look at the result: a simple autorunner with jump and wall jump abilities Just tap or click to make the player jump. Every zone of the level is accessible thanks to wall jump. Try to jump while on a wall and see what happens. I made the level with Tiled Map Editor which is the best choice. This is the level I exported in JSON:
{ "height":15,
"layers":[
{
"data":[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
"height":15,
"name":"layer01",
"opacity":1,
"type":"tilelayer",
"visible":true,
"width":20,
"x":0,
"y":0
}],
"nextobjectid":1,
"orientation":"orthogonal",
"properties":
{
},
"renderorder":"right-down",
"tileheight":32,
"tilesets":[
{
"firstgid":1,
"image":"tile.png",
"imageheight":32,
"imagewidth":32,
"margin":0,
"name":"tileset01",
"properties":
{
},
"spacing":0,
"tilecount":1,
"tileheight":32,
"tilewidth":32
}],
"tilewidth":32,
"version":1,
"width":20
}
var game;
var gameOptions = {
// width of the game, in pixels
gameWidth: 640,
// height of the game, in pixels
gameHeight: 480,
// background color
bgColor: 0x444444,
// player gravity
playerGravity: 900,
// player horizontal speed
playerSpeed: 200,
// player force
playerJump: 400
}
window.onload = function() {
game = new Phaser.Game(gameOptions.gameWidth, gameOptions.gameHeight);
game.state.add("PreloadGame", preloadGame);
game.state.add("PlayGame", playGame);
game.state.start("PreloadGame");
}
var preloadGame = function(game){}
preloadGame.prototype = {
preload: function(){
game.stage.backgroundColor = gameOptions.bgColor;
game.scale.scaleMode = Phaser.ScaleManager.SHOW_ALL;
game.scale.pageAlignHorizontally = true;
game.scale.pageAlignVertically = true;
game.stage.disableVisibilityChange = true;
// loading level tilemap
game.load.tilemap("level", 'level.json', null, Phaser.Tilemap.TILED_JSON);
game.load.image("tile", "tile.png");
game.load.image("hero", "hero.png");
},
create: function(){
game.state.start("PlayGame");
}
}
var playGame = function(game){}
playGame.prototype = {
create: function(){
// starting ARCADE physics
game.physics.startSystem(Phaser.Physics.ARCADE);
// creatin of "level" tilemap
this.map = game.add.tilemap("level");
// adding tiles (actually one tile) to tilemap
this.map.addTilesetImage("tileset01", "tile");
// tile 1 (the black tile) has the collision enabled
this.map.setCollision(1);
// which layer should we render? That's right, "layer01"
this.layer = this.map.createLayer("layer01");
// adding the hero sprite
this.hero = game.add.sprite(game.width / 2, 440, "hero");
// setting hero anchor point
this.hero.anchor.set(0.5);
// enabling ARCADE physics for the hero
game.physics.enable(this.hero, Phaser.Physics.ARCADE);
// setting hero gravity
this.hero.body.gravity.y = gameOptions.playerGravity;
// setting hero horizontal speed
this.hero.body.velocity.x = gameOptions.playerSpeed;
// the hero can jump
this.canJump = true;
// the hero is not on the wall
this.onWall = false;
// waiting for player input
game.input.onDown.add(this.handleJump, this);
},
handleJump: function(){
// the hero can jump when:
// canJump is true AND the hero is on the ground (blocked.down)
// OR
// the hero is on the wall
if((this.canJump && this.hero.body.blocked.down) || this.onWall){
// applying jump force
this.hero.body.velocity.y = -gameOptions.playerJump;
// is the hero on a wall?
if(this.onWall){
// flip horizontally the hero
this.hero.scale.x *= -1;
// change the horizontal velocity too. This way the hero will jump off the wall
this.hero.body.velocity.x = gameOptions.playerSpeed * this.hero.scale.x;
}
// hero can't jump anymore
this.canJump = false;
// hero is not on the wall anymore
this.onWall = false;
}
},
update: function(){
// handling collision between the hero and the tiles
game.physics.arcade.collide(this.hero, this.layer, function(hero, layer){
// hero on the ground
if(hero.body.blocked.down){
// hero can jump
this.canJump = true;
// hero not on the wall
this.onWall = false;
}
// hero on the ground and touching a wall on the right
if(this.hero.body.blocked.right && this.hero.body.blocked.down){
// horizontal flipping hero sprite
this.hero.scale.x = -1;
}
// hero NOT on the ground and touching a wall on the right
if(this.hero.body.blocked.right && !this.hero.body.blocked.down){
// hero on a wall
this.onWall = true;
}
// same concept applies to the left
if(this.hero.body.blocked.left && this.hero.body.blocked.down){
this.hero.scale.x = 1;
}
if(this.hero.body.blocked.left && !this.hero.body.blocked.down){
this.onWall = true;
}
// adjusting hero speed according to the direction it's moving
this.hero.body.velocity.x = gameOptions.playerSpeed * this.hero.scale.x;
}, null, this);
}
}
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