开篇寄语
编写游戏，这个方面伯衡君一直想做，但是一直没提上议程，最近终于有了兴致，就准备开始研究如何编写游戏了，先从JS入手写一个小游戏好了。无论是编写复杂的游戏，还是编写简单的游戏，都是一个个逻辑汇合而成，一个个功能的堆积，堆积的多了，简单的游戏也就变成了复杂的游戏。所以，先分解游戏要实现的目的，之后再按照目的一个个去实现就会事半功倍了。
Demo地址
- https://zhangboheng.github.io/Easy-Web-TV-M3u8/，选择游戏模块后，选择躲避方块游戏即可
游戏目标
- 场景：分数栏，方块，障碍物，控制按钮，移动的场景
- 终止条件：方块碰到顶部和底部的边框或者障碍物，游戏即宣告结束
涉及知识
- html
- css
- javascript
- canvas
完整代码
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
}
canvas {
border: 1px solid #d3d3d3;
background-image: url('../../images/bg.jpg');
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
var myObstacles = [];
var myScore;
function startGame() {
myGamePiece = new component(20, 20, randomColor(), 50, 120);
myGamePiece.gravity = 0.05;
myScore = new component("30px", "Consolas", "white", 20, 40, "text");
myGameArea.start();
}
var myGameArea = {
canvas: document.createElement("canvas"),
start: function() {
this.canvas.width = window.innerWidth - 2;
this.canvas.height = window.innerHeight - 2;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.frameNo = 0;
this.interval = setInterval(updateGameArea, 20);
},
clear: function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
this.score = 0;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.gravity = 0;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
if (this.type == "text") {
ctx.font = this.width + " " + this.height;
ctx.fillStyle = color;
ctx.fillText(this.text, this.x, this.y);
} else {
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
this.hitBottom();
}
this.hitBottom = function() {
var rockbottom = myGameArea.canvas.height - this.height;
if (this.y > rockbottom) {
this.y = rockbottom;
this.gravitySpeed = 0;
}
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
function updateGameArea() {
var x, height, gap, minHeight, maxHeight, minGap, maxGap;
for (i = 0; i < myObstacles.length; i += 1) {
//Set end game conditions
if (myGamePiece.crashWith(myObstacles[i]) || myGamePiece.y == window.innerHeight - 22 || myGamePiece.y <= 0) {
return;
}
}
myGameArea.clear();
myGameArea.frameNo += 1;
if (myGameArea.frameNo == 1 || everyinterval(150)) {
x = myGameArea.canvas.width;
minHeight = 20;
maxHeight = 200;
height = Math.floor(Math.random() * (maxHeight - minHeight + 1) + minHeight);
minGap = 50;
maxGap = 200;
gap = Math.floor(Math.random() * (maxGap - minGap + 1) + minGap);
myObstacles.push(new component(10, height, randomlor(), x, 0));
myObstacles.push(new component(10, x - height - gap, randomlor(), x, height + gap));
}
for (i = 0; i < myObstacles.length; i += 1) {
myObstacles[i].x += -1;
myObstacles[i].update();
}
myScore.text = "SCORE: " + myGameArea.frameNo;
myScore.update();
myGamePiece.newPos();
myGamePiece.update();
}
function everyinterval(n) {
if ((myGameArea.frameNo / n) % 1 == 0) {
return true;
}
return false;
}
function accelerate(n) {
myGamePiece.gravity = n;
}
//Set random square colors
function randomColor() {
let r = Math.floor(Math.random() * 256);
let g = Math.floor(Math.random() * 256);
let b = Math.floor(Math.random() * 256);
return "rgb(" + r + "," + g + "," + b + ")";
}
//Set random line colors
function randomlor() {
let r = Math.floor(Math.random() * 256);
let g = Math.floor(Math.random() * 256);
let b = Math.floor(Math.random() * 256);
return "rgb(" + r + "," + g + "," + b + ")";
}
//Restart game
function restartGame() {
window.location.reload();
}
</script>
<div style="position: relative; bottom: 50px; text-align: center;">
<button onmousedown="accelerate(-0.2)" onmouseup="accelerate(0.05)">ACCELERATE</button>
<button onclick="restartGame()">RESTART</button>
</div>
</body>
</html>
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