// the game itself
var game;
// global object with all customizable options
var gameOptions = {
// radius of the big circle - the "planet" - in pixels
bigCircleRadius: 250,
// radius of the small circle, in pixels
playerRadius: 25,
// player speed, in degrees per frame
playerSpeed: 1,
// world gravity
worldGravity: 0.8,
// jump force. First element is the first jump, second element - if any - the double jump, third element - if any - the triple jump and so on
jumpForce: [12, 9, 6],
// spike size - width, height - in pixels
spikeSize: [25, 50],
// distance needed to consider the player close to a spike, in degrees
closeToSpike: 10,
// distance needed to consider the player far from a spike, in degrees
farFromSpike: 35
}
window.onload = function() {
// game configuration object
var gameConfig = {
thpe: Phaser.CANVAS,
width: 800,
height: 800,
scene: [playGame]
}
game = new Phaser.Game(gameConfig);
window.focus()
resize();
window.addEventListener("resize", resize, false);
}
class playGame extends Phaser.Scene{
constructor(){
super("PlayGame");
}
preload(){
this.load.image("bigcircle", "bigcircle.png");
this.load.image("player", "player.png");
this.load.image("spike", "spike.png");
this.load.image("mask", "mask.png");
}
create(){
// adding a group which will contain all spikes
this.spikeGroup = this.add.group();
// adding the big circle, the "planet", placed in the middle of the canvas
this.bigCircle = this.add.sprite(game.config.width / 2, game.config.height / 2, "bigcircle");
this.bigCircle.displayWidth = gameOptions.bigCircleRadius * 2;
this.bigCircle.displayHeight = gameOptions.bigCircleRadius * 2;
// placing the player, just above the top of the "planet"
this.player = this.add.sprite(game.config.width / 2, game.config.height / 2 - gameOptions.bigCircleRadius - gameOptions.playerRadius, "player");
this.player.displayWidth = gameOptions.playerRadius * 2;
this.player.displayHeight = gameOptions.playerRadius * 2;
// a few custom properties: currentAngle is the angle of the player
this.player.currentAngle = -90;
// jumpOffset is the amount of pixels to be added to player position when it jumps
this.player.jumpOffset = 0;
// how many jumps is the player doing?
this.player.jumps = 0;
// current jump force
this.player.jumpForce = 0;
// when the player clicks/taps on the canvas...
this.input.on("pointerdown", function(e){
// can the player jump?
if(this.player.jumps < gameOptions.jumpForce.length){
// player is jumping once more
this.player.jumps ++;
// adding the proper jump force to player's jumpForce property
this.player.jumpForce = gameOptions.jumpForce[this.player.jumps - 1];
}
}, this);
// we are going to place nine spikes
for(var i = 0; i < 9; i ++){
// adding the spike on the canvas
var spike = this.add.sprite(0, 0, "spike");
// set spike origin point to left and horizontal middle
spike.setOrigin(0, 0.5);
// adding the spike to spike group
this.spikeGroup.add(spike);
// place the spike. Arguments are the spike itself and the quadrant of the big circle
this.placeSpike(spike, Math.floor(i / 3));
}
// adding the mask image which will act like a "fog" to hide and show spikes
this.maskImage = this.add.sprite(game.config.width / 2, game.config.height / 2, "mask");
}
// method to randomly place a spike into a quadrant
placeSpike(spike, quadrant){
// choosing a random angle
var randomAngle = Phaser.Math.Angle.WrapDegrees(Phaser.Math.Between(quadrant * 90, (quadrant + 1) * 90));
// this is the same random angle converted in radians
var randomAngleRadians = Phaser.Math.DegToRad(randomAngle);
// determining spike position according to its angle
var spikeX = this.bigCircle.x + (gameOptions.bigCircleRadius - Phaser.Math.Between(4, 25)) * Math.cos(randomAngleRadians);
var spikeY = this.bigCircle.y + (gameOptions.bigCircleRadius - Phaser.Math.Between(4, 25)) * Math.sin(randomAngleRadians);
spike.x = spikeX;
spike.y = spikeY;
// saving spike's quadrant in a custom property
spike.quadrant = quadrant;
// setting spike angke
spike.angle = randomAngle;
// saving the three spike vertices in custom properties
spike.top = new Phaser.Math.Vector2(spikeX + gameOptions.spikeSize[1] * Math.cos(randomAngleRadians), spikeY + gameOptions.spikeSize[1] * Math.sin(randomAngleRadians));
spike.base1 = new Phaser.Math.Vector2(spikeX + gameOptions.spikeSize[0] / 2 * Math.cos(randomAngleRadians + Math.PI / 2), spikeY + gameOptions.spikeSize[0] / 2 * Math.sin(randomAngleRadians + Math.PI / 2));
spike.base2 = new Phaser.Math.Vector2(spikeX + gameOptions.spikeSize[0] / 2 * Math.cos(randomAngleRadians - Math.PI / 2), spikeY + gameOptions.spikeSize[0] / 2 * Math.sin(randomAngleRadians - Math.PI / 2));
// is the player approaching to the spike?
spike.approaching = false;
}
// method to be executed at each frame
update(){
// is the player jumping?
if(this.player.jumps > 0){
// adjusting player jump offset
this.player.jumpOffset += this.player.jumpForce;
// decreasing jump force due to gravity
this.player.jumpForce -= gameOptions.worldGravity;
// if jumpOffset is less than zero, it means the player touched the ground
if(this.player.jumpOffset < 0){
// setting jump offset to zero
this.player.jumpOffset = 0;
// player is not jumping anymore
this.player.jumps = 0;
// there is no jump force
this.player.jumpForce = 0;
}
}
// setting new player current angle according to current position and speed
this.player.currentAngle = Phaser.Math.Angle.WrapDegrees(this.player.currentAngle + gameOptions.playerSpeed);
// moving the mask image accordingly
this.maskImage.angle = this.player.currentAngle + 90;
// getting the same angle in radians
var radians = Phaser.Math.DegToRad(this.player.currentAngle);
// determining the distance from the center according to planet radius, player radius and jump offset
var distanceFromCenter = (gameOptions.bigCircleRadius * 2 + gameOptions.playerRadius * 2) / 2 + this.player.jumpOffset;
// position the player using trigonometry
this.player.x = this.bigCircle.x + distanceFromCenter * Math.cos(radians);
this.player.y = this.bigCircle.y + distanceFromCenter * Math.sin(radians);
// determining the number of revolutions the player has to do move according to planet and player size
var revolutions = (gameOptions.bigCircleRadius * 2) / (gameOptions.playerRadius * 2) + 1;
// set player rotation according to current angle and the number of revolutions needed
this.player.angle = this.player.currentAngle * revolutions;
// looping through each spike, as child of spikeGroup
this.spikeGroup.children.iterate(function(spike){
// getting angle difference between the spike and the player
var angleDiff = this.getAngleDifference(spike.angle, this.player.currentAngle);
// if the player is not approaching the spike and it's close enough...
if(!spike.approaching && angleDiff < gameOptions.closeToSpike){
// player is approaching the spike
spike.approaching = true;
}
// if the player is approaching the spike...
if(spike.approaching){
// checking for collision between the player and the two triangle sizes
if(this.distToSegmentSquared(new Phaser.Math.Vector2(this.player.x, this.player.y), gameOptions.playerRadius, spike.top, spike.base1) || this.distToSegmentSquared(new Phaser.Math.Vector2(this.player.x, this.player.y), gameOptions.playerRadius, spike.top, spike.base2)){
// restart the game if the collision occurs
this.scene.start("PlayGame");
}
// if we are getting too far from the spike...
if(angleDiff > gameOptions.farFromSpike){
// recycle the spike and move it in a random position three quadrants further
this.placeSpike(spike, (spike.quadrant + 3) % 4);
}
}
}, this)
}
// function to get the minimum difference between two angles a1 and a2
getAngleDifference(a1, a2){
var angleDifference = a1 - a2
angleDifference += (angleDifference > 180) ? -360 : (angleDifference < -180) ? 360 : 0
return Math.abs(angleDifference);
}
// function to get the distance between two points p1 and p2
getDistance(p1, p2){
return (p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y);
}
// function to determine if a circle is touching a line segment given the circle center, the radius and the points defining the segment
distToSegmentSquared(circleCenter, circleRadius, segmentStart, segmentEnd){
var l2 = this.getDistance(segmentStart, segmentEnd);
var t = ((circleCenter.x - segmentStart.x) * (segmentEnd.x - segmentStart.x) + (circleCenter.y - segmentStart.y) * (segmentEnd.y - segmentStart.y)) / l2;
t = Math.max(0, Math.min(1, t));
var tX = segmentStart.x + t * (segmentEnd.x - segmentStart.x);
var tY = segmentStart.y + t * (segmentEnd.y - segmentStart.y);
var tPoint = {
x: tX,
y: tY
}
return this.getDistance(circleCenter, tPoint) < circleRadius * circleRadius;
}
}
// pure javascript to scale the game
function resize() {
var canvas = document.querySelector("canvas");
var windowWidth = window.innerWidth;
var windowHeight = window.innerHeight;
var windowRatio = windowWidth / windowHeight;
var gameRatio = game.config.width / game.config.height;
if(windowRatio < gameRatio){
canvas.style.width = windowWidth + "px";
canvas.style.height = (windowWidth / gameRatio) + "px";
}
else{
canvas.style.width = (windowHeight * gameRatio) + "px";
canvas.style.height = windowHeight + "px";
}
}
HTML5 prototype of a circular endless runner featuring double jump built with Phaser – double, triple, infinite jumps and commented source code
Read all posts about "Circular endless runner" game
Another long title for another update to the HTML5 circular endless runner prototype built with Phaser.
I wanted to build a physics game without using physics and I am doing it quite well. I already developed gravity, jump, double jump and collision detection using only mathematics and trigonometry, and today I have a couple of new features:
* You are not longer limited to jump and double jump, you can adjust the game to let the player make any number of consecutive jumps just by changing a variable.
* There is a fog effect – which is actually a circular gradient fading to black to totally transparent black color – which makes the spikes appear and disappear giving the idea of an endless environment. But they are just 9 sprites placed here and there according to player position.
Have a look at the prototype:
Click or tap to jump and double jump, or even to make a triple jump and see how spikes smoothly appear and disappear.
What about the source code? I commented it line by line. There is still some – or better a lot of – room for improvement but having a source code with all comments will allow you to better understand how I built this prototype and above all to port the game in other languages, since I did not use any physics engine, just mathematics.
Now it’s time to add some kind of score and increase somehow the difficulty as you progress in the game, will do it next week, meanwhile download the source code.
