小游戏敌机出现
英雄飞机也有了,子弹也有了,怎么可以少了飞机呢,对吧
同样,我们也不使用官方的图片,而是使用下面这张雪碧图
- 图片地址为: https://www.twle.cn/static/i/minigame/enemy.png
- 图片大小为
400x100
- 每个子弹大小为
100x100
下载这张图片,并保存到 images
目录
敌机一般都是从顶部出现的,然后一路飞到屏幕的下面
game.js
var c = wx.createCanvas(); var ctx = c.getContext('2d'); var bullet = wx.createImage(); function reset() { ctx.save(); ctx.fillStyle = "#fff"; ctx.fillRect(0, 0, c.width, c.height); ctx.restore(); } function draw_copy() { ctx.save(); ctx.textAlign = "center" // 居中对齐 ctx.textBaseline = "middle" //垂直居中绘制 ctx.fillStyle = "#aaa"; ctx.font = "16px Arial" // 字体大小 16 像素 ctx.fillText("简单教程,简单编程", c.width / 2, (c.height - 108)) ctx.fillText(" © 2015-2018 www.twle.cn", c.width / 2, (c.height - 128)); ctx.restore(); } bullet.onload = function () { reset(ctx); ctx.drawImage(bullet, 0, 0, 100,100, c.width / 2 - 25, 0, 50, 50); draw_copy(); } reset(); bullet.src = 'images/enemy.png'
虽然敌机大小为 100x100
,但我们把它绘制小一点,不然一屏幕都放不下几个敌机
运行效果如下
对敌机进行封装
因为剧情 (接下里的教程) 需要,我们对敌机做一些封装
function Enemy() { // 位置 this.x = 0; this.y = 0; //宽高 this.w = 50; this.h = 50; // 飞行速度 this.speed = 2; // 敌机图片 this.img = null; // 敌机类型 this.kind = 1; // 原图位置 this.rx = 0; this.ry = 0; this.rw = 100; this.rh = 100; this.change_kind = function(k) { this.rx = (k-1) * 100; this.ry = 0; } this.move = function(){ this.y += this.speed; }; this.draw = function(ctx){ ctx.drawImage(this.img,this.rx,this.ry, this.rw,this.rh, this.x-this.w/2,this.y-this.h/2, this.w,this.h); } }
注意
- 我们绘制敌机的时候,
x
和y
所代表的,就是敌机中间的位置- 敌机的飞行方向是从下往上
是不是发现和子弹差不多,对的,等下我们会说
让敌机飞起来
把敌机放到动画里,敌机就会飞起来了
有一个点需要注意,敌机不可能凭空出现对吧,所以敌机初始化的 Y 坐标轴为 -h
然后我们就可以把敌机放到动画里,让敌机飞起来
var c = wx.createCanvas(); var ctx = c.getContext('2d'); var enemy = null; function Enemy() { //宽高 this.w = 50; this.h = 50; // 位置 this.x = 0; this.y = - this.h; // 飞行速度 this.speed = 2; // 敌机图片 this.img = null; // 敌机类型 this.kind = 1; // 原图位置 this.rx = 0; this.ry = 0; this.rw = 100; this.rh = 100; this.change_kind = function(k) { this.rx = (k-1) * 100; this.ry = 0; } this.move = function(){ this.y += this.speed; }; this.draw = function(ctx){ ctx.drawImage(this.img,this.rx,this.ry, this.rw,this.rh, this.x-this.w/2,this.y-this.h/2, this.w,this.h); } } function reset() { ctx.save(); ctx.fillStyle = "#fff"; ctx.fillRect(0, 0, c.width, c.height); ctx.restore(); } function draw_copy() { ctx.save(); ctx.textAlign = "center" // 居中对齐 ctx.textBaseline = "middle" //垂直居中绘制 ctx.fillStyle = "#aaa"; ctx.font = "16px Arial" // 字体大小 16 像素 ctx.fillText("简单教程,简单编程", c.width / 2, (c.height - 108)) ctx.fillText(" © 2015-2018 www.twle.cn", c.width / 2, (c.height - 128)); ctx.restore(); } function animate_it() { reset(ctx); enemy.move(); enemy.draw(ctx); draw_copy(); requestAnimationFrame(animate_it); } enemy = new Enemy(); enemy.x = c.width / 2; enemy.y = - enemy.h; enemy.img = wx.createImage(); enemy.img.onload = function () { reset(ctx); enemy.draw(ctx); draw_copy(); requestAnimationFrame(animate_it); } reset(); enemy.img.src = 'images/enemy.png'
运行演示如下
更多敌机
我们每 800ms
产生一个敌机
这时候要使用一个数组来存储全部的敌机,还要检查敌机是否超出边界,如果超出了边界就删除敌机
注意,一般来说,敌机的产生速度要远远小于子弹的,不然子弹都忙不过来不是
还有一点,敌机的位置是随机的,所以我们要使用随机数创建一个敌机位置
game.js
var c = wx.createCanvas(); var ctx = c.getContext('2d'); var screenHeight = c.height; var screenWidth = c.width; function Enemy() { //宽高 this.w = 50; this.h = 50; // 位置 this.x = 0; this.y = - this.h; // 飞行速度 this.speed = 2; // 敌机图片 this.img = null; // 敌机类型 this.kind = 1; // 原图位置 this.rx = 0; this.ry = 0; this.rw = 100; this.rh = 100; this.change_kind = function (k) { this.rx = (k - 1) * 100; this.ry = 0; } this.move = function () { this.y += this.speed; }; this.draw = function (ctx) { ctx.drawImage(this.img, this.rx, this.ry, this.rw, this.rh, this.x - this.w / 2, this.y - this.h / 2, this.w, this.h); } } var Enemys = { _data: [], move: function () { for (var i in this._data) { this._data[i].move(); if (this._data[i].y >= screenHeight) { this._data.splice(i, 1); } } }, add: function (enemy) { this._data.push(enemy); }, draw: function (ctx) { for (var i in this._data) { this._data[i].draw(ctx); } } } function reset() { ctx.save(); ctx.fillStyle = "#fff"; ctx.fillRect(0, 0, c.width, c.height); ctx.restore(); } function draw_copy() { ctx.save(); ctx.textAlign = "center" // 居中对齐 ctx.textBaseline = "middle" //垂直居中绘制 ctx.fillStyle = "#aaa"; ctx.font = "16px Arial" // 字体大小 16 像素 ctx.fillText("简单教程,简单编程", c.width / 2, (c.height - 108)) ctx.fillText(" © 2015-2018 www.twle.cn", c.width / 2, (c.height - 128)); ctx.restore(); } function animate_it() { reset(ctx); Enemys.move(); Enemys.draw(ctx); draw_copy(); requestAnimationFrame(animate_it); } function create_enemy(img) { var enemy = new Enemy(); enemy.x = (enemy.w / 2) + Math.random() * (screenWidth - enemy.w / 2); enemy.y = - enemy.h; enemy.img = img; Enemys.add(enemy); } var enemy_img = wx.createImage(); enemy_img.onload = function () { reset(ctx); create_enemy(enemy_img); Enemys.draw(ctx); draw_copy(); setInterval(function () { create_enemy(enemy_img); }, 800); requestAnimationFrame(animate_it); } reset(); enemy_img.src = 'images/enemy.png'
运行演示如下
把敌机也绘制到游戏上
好了,加下来就是组装我们的敌机和之前已经做好的游戏了
除了组长之外,还有一个很重要的工作,就是合并
我们发现敌机和子弹所使用的信息都差不多,连保存数组也差不多,那么我们就可以把它们的主要代码合并
game.js
var inherits = function (superCtor) { var f = function () { superCtor.call(this); } f.super_ = superCtor; f.prototype = Object.create(superCtor.prototype, { constructor: { value: f, enumerable: false, writable: true, configurable: true } }); return f; }; var Resource = { _res: [], // [][] 资源对象数组, 0 表示资源 1 url 2 类型 3 是否加载完成 _load: function (idx, ops) { var res = this._res[idx]; if (!res[3]) { if (res[2] == "audio") this._load_audio(res[1], idx, ops) if (res[2] == "image") this._load_image(res[1], idx, ops); } }, _load_image: function (src, i, ops) { var img = wx.createImage(); var that = this; that._res[i][0] = img; img.onload = function () { that._res[i][3] = true; } img.src = src; }, _load_audio: function (src, i, ops) { var audio = wx.createInnerAudioContext(); if (ops != null) { for (var k in ops) { audio[k] = ops[k]; } } var that = this; that._res[i][0] = audio; audio.onCanplay(function () { that._res[i][3] = true; }); audio.src = src; }, loaded: function (callback) { for (var i = 0; i < this._res.length; i++) { if (!this._res[i][3]) { var that = this; setTimeout(function () { that.loaded(callback); }, 200); return; } } callback(); }, add: function (src, type, id, ops) { this._res.push([null, src, type, false, id]); this._load(this._res.length-1, ops); }, item: function (src) { for (var i = 0; i < this._res.length; i++) { if (this._res[i][1] == src) { return this._res[i][0]; } } return null; } } var Bucket = { _bucket: {}, move: function () { for (var i in this._bucket) { for (var j in this._bucket[i]) { this._bucket[i][j].move(); if (this._bucket[i][j].hit()) { this._bucket[i].splice(j, 1); } } } }, add: function (obj, bucket) { if (!(bucket in this._bucket)) { this._bucket[bucket] = []; } this._bucket[bucket].push(obj); }, draw: function (ctx) { for (var i in this._bucket) { for (var j in this._bucket[i]) { this._bucket[i][j].draw(); } } } } function Sprite() { // 位置 this.x = 0; this.y = 0; //宽高 this.w = 0; this.h = 0; // 飞行速度 this.speed = 0; // 图片 this.img = null; // 类型 this.kind = 0; // 原图位置 this.rx = 0; this.ry = 0; this.rw = 0; this.rh = 0; this.ctx = null; this.change_kind = function (k) { this.rx = (k - 1) * this.rw; this.ry = 0; } this.move = function () { this.y += this.speed; }; this.draw = function () { this.ctx.drawImage(this.img, this.rx, this.ry, this.rw, this.rh, this.x - this.w / 2, this.y - this.h / 2, this.w, this.h); } } var Bullet = inherits(Sprite); Bullet.prototype.hit = function () { return this.y <= 0; } var Enemy = inherits(Sprite); Enemy.prototype.hit = function () { return this.y >= screenHeight; } var c = wx.createCanvas(); var ctx = c.getContext('2d'); var img = wx.createImage(); var plane = wx.createImage(); var bgCanvas = null; var offset = 0; var w = 0; var h = 0; var screenWidth = c.width; var screenHeight = c.height; // 上一次飞机的位置 var lasted = { x: 0, y: 0 }; // 触摸区域是否在飞机内部 var in_plane = false; // 创建计时器 var t = 0; function init_bg() { bgCanvas = wx.createCanvas(); bgCanvas.width = screenWidth; bgCanvas.height = screenHeight + h; var bgctx = bgCanvas.getContext('2d'); var y = 0; var x = 0; // 底部多绘制一张图片 while (y < screenHeight + h) { x = 0; while (x < screenWidth) { bgctx.drawImage(img, x, y, w, h); x += w; } y += h; } } function reset() { ctx.save(); ctx.fillStyle = "#fff"; ctx.fillRect(0, 0, c.width, c.height); ctx.restore(); } function draw_copy() { ctx.save(); ctx.textAlign = "center" // 居中对齐 ctx.textBaseline = "middle" //垂直居中绘制 ctx.fillStyle = "#aaa"; ctx.font = "16px Arial" // 字体大小 16 像素 ctx.fillText("简单教程,简单编程", c.width / 2, (c.height - 36)) ctx.fillText(" © 2015-2018 www.twle.cn", c.width / 2, (c.height - 18)); ctx.restore(); } function animate_it() { reset(ctx); ctx.drawImage(bgCanvas, 0, offset, screenWidth, screenHeight, 0, 0, screenWidth, screenHeight); Bucket.move(); Bucket.draw(ctx); ctx.drawImage(plane, 0, 0, 128, 128, lasted.x - 64, lasted.y - 64, 128, 128); draw_copy(); timeit(); offset; if (offset % h == 0) { offset = 0; } requestAnimationFrame(animate_it); } wx.onShow(function () { Resource.item('audio/bgm.mp3').play(); }) wx.onAudioInterruptionBegin(function () { // 暂停音乐 Resource.item('audio/bgm.mp3').stop(); // 中断动画 //cancelAnimationFrame(animate_it); }) wx.onAudioInterruptionEnd(function () { Resource.item('audio/bgm.mp3').play() // 恢复动画 cancelAnimationFrame(animate_it); }) wx.onTouchStart(function (e) { var x = e.touches[0].clientX; var y = e.touches[0].clientY; if (plane_hit(x, y)) { in_plane = true; } }); wx.onTouchEnd(function (e) { if (in_plane) { lasted.x = e.touches[0].clientX; lasted.y = e.touches[0].clientY; in_plane = false; } }); // 触摸移动事件 wx.onTouchMove(function (e) { if (in_plane) { lasted.x = e.touches[0].clientX; lasted.y = e.touches[0].clientY; } }) function plane_hit(x, y) { return x > (lasted.x - 64) && x < (lasted.x + 64) && y > (lasted.y - 64) && y < (lasted.y + 64); } function start() { w = screenWidth > img.width ? img.width : screenWidth; h = img.height * (w / img.width); lasted.x = (screenWidth - 128) / 2; lasted.y = screenHeight - 128; var bgm = Resource.item('audio/bgm.mp3').play(); init_bg(); ctx.drawImage(plane, 0, 0, 128, 128, lasted.x, lasted.y, 128, 128); draw_copy(); requestAnimationFrame(animate_it); } function create_bullet(img) { var bullet = new Bullet(); bullet.x = lasted.x; bullet.y = lasted.y; bullet.img = img; bullet.w = 30; bullet.h = 30; bullet.speed = - 2; bullet.img = img; bullet.kind = 1; bullet.rw = 60; bullet.rh = 60; bullet.ctx = ctx; Bucket.add(bullet, 'buttet'); } function create_enemy(img) { var enemy = new Enemy(); enemy.w = 50; enemy.h = 50; enemy.x = (enemy.w / 2) + Math.random() * (screenWidth - enemy.w / 2); enemy.y = -50; enemy.img = img; enemy.speed = 2; enemy.img = img; enemy.kind = 1; enemy.rw = 100; enemy.rh = 100; enemy.ctx = ctx; Bucket.add(enemy, 'enemy'); } function timeit() { if (t % 60 == 0) { var enemy = Resource.item('images/enemy.png'); create_enemy(enemy); } if (in_plane && t % 20 == 0) { var bullet = Resource.item('images/bullet.png'); create_bullet(bullet); } t++; } reset(); Resource.add('images/bg.jpg', 'image'); Resource.add('audio/bgm.mp3', 'audio', null, { loop: true }); Resource.add('images/plane.png', 'image'); Resource.add('images/bullet.png', 'image'); Resource.add('images/enemy.png', 'image'); Resource.loaded(function () { img = Resource.item('images/bg.jpg'); plane = Resource.item('images/plane.png'); start(); });
运行演示如下
手机录制视频会严重掉帧