Hop Hop Hop Underwater is a game developed by Ketchapp you can find both on App Store and Google Play.
In the game you control a character which can hop above and under the water.
When above the water, you must tap to jump. When underwater, you must tap to dive.
We can build a HTML5 prototype in a few lines using Phaser, this way:
Tap to hop if you’re above the water, or to dive if you are underwater.
In the completely commented source code, you can see it’s just a matter to switch player gravity at the right time, as well as inverting the thrust if we are underwater.
The concept is: jump force must be always against gravity direction, have a look at the source code:
let game;
let gameOptions = {
// water level, in % of screen height
waterLevel: 50,
// ball gravity
ballGravity: 1600,
// jump power
ballPower: 800
}
window.onload = function() {
let gameConfig = {
type: Phaser.AUTO,
backgroundColor:0x888888,
scale: {
mode: Phaser.Scale.FIT,
autoCenter: Phaser.Scale.CENTER_BOTH,
parent: "thegame",
width: 750,
height: 1334
},
physics: {
default: "arcade",
arcade: {
gravity: {
y: 0
}
}
},
scene: playGame
}
game = new Phaser.Game(gameConfig);
window.focus();
}
class playGame extends Phaser.Scene{
constructor(){
super("PlayGame");
}
preload(){
this.load.image("ball", "ball.png");
this.load.image("water", "water.png");
}
create(){
// add water sprite
this.water = this.add.sprite(0, game.config.height / 100 * gameOptions.waterLevel, "water");
// set registration point to top left pixel
this.water.setOrigin(0, 0);
// set display width to cover the entire game width
this.water.displayWidth = game.config.width;
// set display height to cover from water level to the bottom of the canvas
this.water.displayHeight = game.config.height - this.water.y;
// add ball sprite
this.ball = this.physics.add.sprite(game.config.width / 2, game.config.height / 4, "ball");
// set ball ballGravity
this.ball.body.gravity.y = gameOptions.ballGravity * (this.isUnderwater() ? -1 : 1)
// listener for input, calls "jump" method
this.input.on("pointerdown", this.jump, this);
}
// method to make ball jump
jump(){
// set ball velocity to positive or negative jump speed according to ball position
this.ball.body.velocity.y = gameOptions.ballPower * (this.isUnderwater() ? 1 : -1);
}
// method to check if the ball is underwater
isUnderwater(){
// true if ball y position is higher than water level
return this.ball.y > game.config.height / 100 * gameOptions.waterLevel
}
update(){
// determine next ball gravity
let nextGravity = gameOptions.ballGravity * (this.isUnderwater() ? -1 : 1);
// is next ball gravity different than current ball gravity?
// this means we moved from land to water or from water to land
if(nextGravity != this.ball.body.gravity.y){
// set ball ballGravity
this.ball.body.gravity.y = nextGravity;
// set ball velocity as if we just jumped
this.ball.body.velocity.y = gameOptions.ballPower * (this.isUnderwater() ? 1 : -1);
}
}
}
I am using Phaser for years, but I always get impressed by how easy is to build hyper casual games with it. Next time we’ll add some enemies, meanwhile download the source code.
