Talking about Hero Slide game, Game development, HTML5, Javascript and Phaser.
To continue the Hero Slide prototype added a couple of weeks ago, we need to properly handle animations and allow only legal moves. Let’s make a small recap: In step 1 we saw how to * Initialize the game * Place random tiles on the map * Move tiles with WASD keys Then in step 2 we added these features: * Add animation to tile creation and movement * Match tiles Finally in step 3 we covered: * code optimization * explosions Talking about explosions, it wasn’t a nice effect due to a messy animation management, so in this 4th step we will see how to syncronize animations and don’t let new items appear if the player did not perform a legal move. Move tiles with WASD keys and try to match normal tiles and bombs – focus the canvas first. The key to handle animations is to keep track of how many tiles we are moving withmovingTiles variable, which increases each time we are about to move a tile with a tween, and decreases once the tween is completed. This time we can know when every tween has been completed and act accordingly.
Each player move now is managed this way.
* We see if it’s a valid move. If not, we wait for another move.
* We move the tiles, disabiling player movement.
* We match all tiles according to game rules.
* For each bomb matched – if any – we make an explosion.
* We allow the player to move again.
And this is the commented source code.
// the game
var game;
// size of each tile, in pixels
var tileSize = 120;
// different kinds of tiles
var tileTypes = 5;
// the game array, the board will be stored here
var gameArray = [];
// field size, in tiles. This will represent a 4x4 tiles field
var fieldSize = 4;
// duration of each tween
var tweenDuration = 100;
// creation of the game
window.onload = function() {
game = new Phaser.Game(480, 480);
game.state.add("PlayGame", playGame);
game.state.start("PlayGame");
}
var playGame = function(game){}
playGame.prototype = {
preload: function(){
// preloading the assets
game.load.spritesheet("tiles", "tiles.png", tileSize, tileSize);
},
create: function(){
// initializing game board
for(var i = 0; i < fieldSize; i++){
gameArray[i] = [];
for(var j = 0; j < fieldSize; j++){
// each array item is an object with a tile value (0: empty) and a sprite (null: no sprite)
gameArray[i][j] = {
tileValue : 0,
tileSprite: null
};
}
}
// function to add a new item, will be explained later
this.addItem();
// liteners to handle WASD keys. Each key calls handleKey function
this.upKey = game.input.keyboard.addKey(Phaser.Keyboard.W);
this.upKey.onDown.add(this.handleKey, this);
this.downKey = game.input.keyboard.addKey(Phaser.Keyboard.S);
this.downKey.onDown.add(this.handleKey, this);
this.leftKey = game.input.keyboard.addKey(Phaser.Keyboard.A);
this.leftKey.onDown.add(this.handleKey, this);
this.rightKey = game.input.keyboard.addKey(Phaser.Keyboard.D);
this.rightKey.onDown.add(this.handleKey, this);
},
// this function will add a new item to the board
addItem: function(){
// emptySpots is an array which will contain all the available empty tiles where to place a new item
var emptySpots = [];
// now we loop through the game board to check for empty tiles
for(var i = 0; i < fieldSize; i++){
for(var j = 0; j < fieldSize; j++){
// remember we define an empty tile as a tile whose tileValue is zero
if(gameArray[i][j].tileValue == 0){
// at this time we push a Point with tile coordinates into emptySpots array
emptySpots.push(new Phaser.Point(j, i));
}
}
}
// newSpot is a randomly picked item in emptySpots array
var newSpot = Phaser.ArrayUtils.getRandomItem(emptySpots);
// if newSpot is not null this means we have a place where to put a new tile
if(newSpot != null){
// selecting a random value between 1 and tileTypes
var tileType = game.rnd.between(1, tileTypes);
// updating game array with the new tile value and sprite
gameArray[newSpot.y][newSpot.x] = {
tileValue: tileType,
tileSprite: game.add.sprite(newSpot.x * tileSize, newSpot.y * tileSize, "tiles", tileType - 1)
}
// we start with the alpha at zero to create a "fade in" tween
gameArray[newSpot.y][newSpot.x].tileSprite.alpha = 0;
// here is the fade in effect
var fadeTween = game.add.tween(gameArray[newSpot.y][newSpot.x].tileSprite).to({
alpha: 1
}, tweenDuration, Phaser.Easing.Linear.None, true);
// now the player can move
fadeTween.onComplete.add(function(e){
// the player can move again
this.canMove = true;
}, this);
}
},
// this function handles player movements
handleKey: function(e){
// variable to count the number of moving tiles
this.movingTiles = 0;
// we have to see if the player actually moved
this.playerMoved = false;
// first of all, let's see if the player can move
if(this.canMove){
// if the player can move, let's set canMove to false to prevent the player to move twice
this.canMove=false;
// initialize a detonation array. Will store all detonations, if any, to perform at the end of the turn
this.detonations = [];
this.detonations.length = 0;
// time to check for the keycode which generated the event
switch(e.keyCode){
// "A" key (left)
case Phaser.Keyboard.A:
// we scan for game field, from TOP to BOTTOM and from LEFT to RIGHT starting from the 2nd column
for(var i = 0; i < fieldSize; i++){
for(var j = 1; j < fieldSize; j++){
// we can move a tile if it's not empty and the tile on its left is empty
if(gameArray[i][j].tileValue != 0 && gameArray[i][j - 1].tileValue == 0){
// moving the tile
this.moveTile(i, j, i, j - 1);
}
else{
// we can match a tile if it's not empty and the tile on its left has the same value
if(gameArray[i][j].tileValue != 0 && gameArray[i][j - 1].tileValue == gameArray[i][j].tileValue){
// removing the item
this.moveAndRemove(i, j, {x: gameArray[i][j].tileSprite.x - tileSize}, i, j - 1)
}
}
}
}
break;
// "W" key (up)
case Phaser.Keyboard.W:
// we scan for game field, from TOP to BOTTOM and from LEFT to RIGHT starting from the 2nd row
// applying the same concepts seen before
for(var i = 1; i < fieldSize; i++){
for(var j = 0; j < fieldSize; j++){
if(gameArray[i][j].tileValue != 0 && gameArray[i - 1][j].tileValue == 0){
this.moveTile(i, j, i - 1, j);
}
else{
if(gameArray[i][j].tileValue != 0 && gameArray[i - 1][j].tileValue == gameArray[i][j].tileValue){
this.moveAndRemove(i, j, {y: gameArray[i][j].tileSprite.y - tileSize}, 1 - 1, j)
}
}
}
}
break;
// "D" key (right)
case Phaser.Keyboard.D:
// we scan for game field, from TOP to BOTTOM and from RIGHT to LEFT starting from the next-to-last column
// applying the same concepts seen before
for(var i = 0; i < fieldSize; i++){
for(var j = fieldSize - 2; j >= 0; j--){
if(gameArray[i][j].tileValue != 0 && gameArray[i][j + 1].tileValue == 0){
this.moveTile(i, j, i, j + 1);
}
else{
if(gameArray[i][j].tileValue != 0 && gameArray[i][j + 1].tileValue == gameArray[i][j].tileValue){
this.moveAndRemove(i, j, {x: gameArray[i][j].tileSprite.x + tileSize}, i, j + 1)
}
}
}
}
break;
// "S" key (down)
case Phaser.Keyboard.S:
// we scan for game field, from BOTTOM to TOP and from LEFT to RIGHT starting from the next-to-last row
// applying the same concepts seen before
for(var i = fieldSize - 2; i >= 0; i--){
for(var j = 0; j < fieldSize; j++){
if(gameArray[i][j].tileValue != 0 && gameArray[i + 1][j].tileValue == 0){
this.moveTile(i, j, i + 1, j);
}
else{
if(gameArray[i][j].tileValue != 0 && gameArray[i + 1][j].tileValue == gameArray[i][j].tileValue){
this.moveAndRemove(i, j, {y: gameArray[i][j].tileSprite.y + tileSize}, i + 1, j)
}
}
}
}
break;
}
// checking for invalid move
if(!this.playerMoved){
this.canMove = true;
}
}
},
// function to move a tile
moveTile: function(row, col, toRow, toCol){
// another moving tile
this.movingTiles ++;
// moving the tile
var moveTween = game.add.tween(gameArray[row][col].tileSprite).to({
x: gameArray[row][col].tileSprite.x + tileSize * (toCol - col),
y: gameArray[row][col].tileSprite.y + tileSize * (toRow - row)
}, tweenDuration, Phaser.Easing.Linear.None, true);
moveTween.onComplete.add(function(e){
this.endMove();
}, this);
// copying the content of the current tile on the destination tile
gameArray[toRow][toCol] = {
tileValue: gameArray[row][col].tileValue,
tileSprite: gameArray[row][col].tileSprite
}
// setting current tile to empty
gameArray[row][col] = {
tileValue: 0,
tileSprite: null
}
// the player moved!
this.playerMoved = true;
},
// function to move and remove a tile
moveAndRemove: function(row, col, toObject, toRow, toCol){
// another moving tile
this.movingTiles ++;
var moveTween = game.add.tween(gameArray[row][col].tileSprite).to(toObject, tweenDuration, Phaser.Easing.Linear.None, true);
moveTween.onComplete.add(function(e){
e.destroy();
this.endMove();
}, this);
// looking at tile type to see what to do next - at the moment we only manage bombs
switch(gameArray[row][col].tileValue){
// bomb
case 4:
// let's add detonation coordinates to detonations array
this.detonations.push(new Phaser.Point(toCol, toRow));
}
gameArray[row][col] = {
tileValue: 0,
tileSprite: null
}
},
// function to just remove a tile
removeTile: function(row, col){
// another moving tile (ok we are removing it but it's the same)
this.movingTiles ++;
var removeTween = game.add.tween(gameArray[row][col].tileSprite).to({
alpha: 0
}, tweenDuration, Phaser.Easing.Linear.None, true);
removeTween.onComplete.add(function(e){
this.movingTiles --;
gameArray[row][col].tileSprite.destroy();
gameArray[row][col] = {
tileValue: 0,
tileSprite: null
}
if(this.movingTiles == 0){
this.addItem();
}
}, this);
},
// function to end a move
endMove: function(){
// one less tile to move
this.movingTiles --;
// if there aren't moving tiles...
if(this.movingTiles == 0){
// do we have to handle detonations or just add a new item?
if(this.detonations.length > 0){
this.handleDetonations();
}
else{
this.addItem();
}
}
},
// handling detonations
handleDetonations: function(){
// looping through all detonations
for(var i = 0; i < this.detonations.length; i++){
// removing the bomb
this.removeTile(this.detonations[i].y, this.detonations[i].x)
// handle detonations
if(this.detonations[i].y - 1 >= 0 && gameArray[this.detonations[i].y - 1][this.detonations[i].x].tileValue != 0){
this.removeTile(this.detonations[i].y - 1, this.detonations[i].x)
}
if(this.detonations[i].y + 1 < fieldSize && gameArray[this.detonations[i].y + 1][this.detonations[i].x].tileValue != 0){
this.removeTile(this.detonations[i].y + 1, this.detonations[i].x)
}
if(this.detonations[i].x - 1 >= 0 && gameArray[this.detonations[i].y][this.detonations[i].x - 1].tileValue != 0){
this.removeTile(this.detonations[i].y, this.detonations[i].x - 1)
}
if(this.detonations[i].x + 1 < fieldSize && gameArray[this.detonations[i].y][this.detonations[i].x + 1].tileValue != 0){
this.removeTile(this.detonations[i].y, this.detonations[i].x + 1)
}
}
}
}
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