极客教程Flappy Bird游戏使用JavaScript编写
Flappy Bird是一款无尽的游戏，玩家可以控制一只鸟。玩家需要防止鸟与管道等障碍物碰撞。每次鸟穿过管道时，得分增加一点。游戏在鸟与管道碰撞或因重力坠落时结束。下面的部分描述了构建此游戏所需的步骤。
HTML部分： 在此部分，创建和加载游戏的元素。选择背景、鸟、障碍物和得分元素的图像。接下来，我们创建并链接style.css和index.js文件。
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div class="background"></div>
<img class="bird" src="logo.png" alt="bird-img">
<div class="message">
Press Enter To Start Game
</div>
<div class="score">
<span class="score_title"></span>
<span class="score_val"></span>
</div>
<script src="gfg.js"></script>
</body>
</html>
CSS部分： 根据需要，此部分修改游戏对象的大小、位置和样式。
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
body {
height: 100vh;
width: 100vw;
}
.background {
height: 100vh;
width: 100vw;
background-color: skyblue;
}
.bird {
height: 100px;
width: 160px;
position: fixed;
top: 40vh;
left: 30vw;
z-index: 100;
}
.pipe_sprite {
position: fixed;
top: 40vh;
left: 100vw;
height: 70vh;
width: 6vw;
background-color: green;
}
.message {
position: fixed;
z-index: 10;
height: 10vh;
font-size: 10vh;
font-weight: 100;
color: black;
top: 12vh;
left: 20vw;
text-align: center;
}
.score {
position: fixed;
z-index: 10;
height: 10vh;
font-size: 10vh;
font-weight: 100;
color: goldenrod;
top: 0;
left: 0;
}
.score_val {
color: gold;
}
JavaScript部分： 该部分包含了控制游戏状态和移动对象的代码部分。在该部分中，需要按照以下步骤进行操作。
- 在JavaScript文件中获取对鸟和背景图像的引用。
- 为背景滚动速度、鸟的飞行速度和重力设置一些值。
- 创建无限滚动背景。
- 添加事件监听器，监听“enter”键按下事件，将游戏状态改为播放状态，并通过每帧减少鸟的y坐标上的重力值，施加重力。
- 在视图宽度结尾处生成障碍（管道），使其初始时不可见，但随着背景的移动，通过减少管道的x坐标来移动，这样看起来就像鸟在移动。
- 与地面和管道发生碰撞，如果鸟发生碰撞，则将游戏状态改为结束状态，并显示重新开始游戏的消息。
- 在每次成功通过管道之后，增加分数值。
// Background scrolling speed
let move_speed = 3;
// Gravity constant value
let gravity = 0.5;
// Getting reference to the bird element
let bird = document.querySelector('.bird');
// Getting bird element properties
let bird_props = bird.getBoundingClientRect();
let background =
document.querySelector('.background')
.getBoundingClientRect();
// Getting reference to the score element
let score_val =
document.querySelector('.score_val');
let message =
document.querySelector('.message');
let score_title =
document.querySelector('.score_title');
// Setting initial game state to start
let game_state = 'Start';
// Add an eventlistener for key presses
document.addEventListener('keydown', (e) => {
// Start the game if enter key is pressed
if (e.key == 'Enter' &&
game_state != 'Play') {
document.querySelectorAll('.pipe_sprite')
.forEach((e) => {
e.remove();
});
bird.style.top = '40vh';
game_state = 'Play';
message.innerHTML = '';
score_title.innerHTML = 'Score : ';
score_val.innerHTML = '0';
play();
}
});
function play() {
function move() {
// Detect if game has ended
if (game_state != 'Play') return;
// Getting reference to all the pipe elements
let pipe_sprite = document.querySelectorAll('.pipe_sprite');
pipe_sprite.forEach((element) => {
let pipe_sprite_props = element.getBoundingClientRect();
bird_props = bird.getBoundingClientRect();
// Delete the pipes if they have moved out
// of the screen hence saving memory
if (pipe_sprite_props.right <= 0) {
element.remove();
} else {
// Collision detection with bird and pipes
if (
bird_props.left < pipe_sprite_props.left +
pipe_sprite_props.width &&
bird_props.left +
bird_props.width > pipe_sprite_props.left &&
bird_props.top < pipe_sprite_props.top +
pipe_sprite_props.height &&
bird_props.top +
bird_props.height > pipe_sprite_props.top
) {
// Change game state and end the game
// if collision occurs
game_state = 'End';
message.innerHTML = 'Press Enter To Restart';
message.style.left = '28vw';
return;
} else {
// Increase the score if player
// has the successfully dodged the
if (
pipe_sprite_props.right < bird_props.left &&
pipe_sprite_props.right +
move_speed >= bird_props.left &&
element.increase_score == '1'
) {
score_val.innerHTML = +score_val.innerHTML + 1;
}
element.style.left =
pipe_sprite_props.left - move_speed + 'px';
}
}
});
requestAnimationFrame(move);
}
requestAnimationFrame(move);
let bird_dy = 0;
function apply_gravity() {
if (game_state != 'Play') return;
bird_dy = bird_dy + gravity;
document.addEventListener('keydown', (e) => {
if (e.key == 'ArrowUp' || e.key == ' ') {
bird_dy = -7.6;
}
});
// Collision detection with bird and
// window top and bottom
if (bird_props.top <= 0 ||
bird_props.bottom >= background.bottom) {
game_state = 'End';
message.innerHTML = 'Press Enter To Restart';
message.style.left = '28vw';
return;
}
bird.style.top = bird_props.top + bird_dy + 'px';
bird_props = bird.getBoundingClientRect();
requestAnimationFrame(apply_gravity);
}
requestAnimationFrame(apply_gravity);
let pipe_seperation = 0;
// Constant value for the gap between two pipes
let pipe_gap = 35;
function create_pipe() {
if (game_state != 'Play') return;
// Create another set of pipes
// if distance between two pipe has exceeded
// a predefined value
if (pipe_seperation > 115) {
pipe_seperation = 0
// Calculate random position of pipes on y axis
let pipe_posi = Math.floor(Math.random() * 43) + 8;
let pipe_sprite_inv = document.createElement('div');
pipe_sprite_inv.className = 'pipe_sprite';
pipe_sprite_inv.style.top = pipe_posi - 70 + 'vh';
pipe_sprite_inv.style.left = '100vw';
// Append the created pipe element in DOM
document.body.appendChild(pipe_sprite_inv);
let pipe_sprite = document.createElement('div');
pipe_sprite.className = 'pipe_sprite';
pipe_sprite.style.top = pipe_posi + pipe_gap + 'vh';
pipe_sprite.style.left = '100vw';
pipe_sprite.increase_score = '1';
// Append the created pipe element in DOM
document.body.appendChild(pipe_sprite);
}
pipe_seperation++;
requestAnimationFrame(create_pipe);
}
requestAnimationFrame(create_pipe);
}
输出：
