这篇文章的游戏使用SpriteKit和Swift语言来完毕。
SpriteKit是苹果自己的游戏引擎,更能贴合iOS系统底层的API,只是架构和实现上都是模仿了Cocos2D。所以使用上事实上区别不大,只是SpriteKit更轻量级一些。
程序入口
main函数跟OC一样,将入口指向了appdelegate,而cocoa touch框架差点儿跟OC一样,仅仅只是用Swift重写了一遍。
这些模板自带的方法跟OC项目并无差异。。。
開始编写游戏
假设你了解CCNode,CCSprite,CCScene等那看起SpriteKit差点儿没有不论什么问题。
override func viewWillLayoutSubviews() { super.viewWillLayoutSubviews() var skView : SKView = self.view as SKView if !skView.scene { //DEBUG skView.showsFPS = true skView.showsNodeCount = true var scene : SKScene = GameScene.sceneWithSize(skView.bounds.size) scene.scaleMode = .AspectFill skView.presentScene(scene) } }
因为当viewDidLoad方法被调用时,skView还没有被加到view的层级结构上,因而它不能相应方向以及布局的改变。所以skView的bounds属性此时还不是它横屏后的正确值,而是默认竖屏所相应的值,看来这个时候不是初始化scene的好时机。所以我们须要将这部分代码挪到将要布局子视图的方法中。
播放背景音乐
这里我们使用AVAudioPlayer来播放音乐。
Controller中声明一个属性
var backgroundMusicPlayer : AVAudioPlayer?
func setupMedia() { var error : NSError? let backgroundMusicURL : NSURL = NSBundle.mainBundle().URLForResource(BG_MUSIC_NAME, withExtension: "caf") backgroundMusicPlayer = AVAudioPlayer(contentsOfURL: backgroundMusicURL , error: &error) if error { println("load background music error : \(error)") } else { backgroundMusicPlayer!.numberOfLoops = -1 backgroundMusicPlayer!.prepareToPlay() backgroundMusicPlayer!.play() } }
override func viewDidLoad() { super.viewDidLoad() setupMedia() }
在视图载入完成时開始播放。
游戏场景
我们建了一个SKScene的子类来进行游戏显示和逻辑的编写。
class GameScene: SKScene
胜利失败场景
class GameOverScene : SKScene { convenience init(size: CGSize, won: Bool) { self.init(size: size) self.backgroundColor = SKColor(red:1.0, green:1.0, blue:1.0, alpha:1.0) self.setupMsgLabel(isWon :won) self.directorAction() } func setupMsgLabel(isWon won: Bool) { var msg: String = won ? "Yow Won!" : "You Lose :[" var msgLabel = SKLabelNode(fontNamed: "Chalkduster") msgLabel.text = msg msgLabel.fontSize = 40 msgLabel.fontColor = SKColor.blackColor() msgLabel.position = CGPointMake(self.size.width/2, self.size.height/2) self.addChild(msgLabel) } func directorAction() { var actions: AnyObject[] = [ SKAction.waitForDuration(3.0), SKAction.runBlock({ var reveal = SKTransition.flipHorizontalWithDuration(0.5) var gameScene = GameScene(size: self.size) self.view.presentScene(gameScene, transition: reveal) }) ] var sequence = SKAction.sequence(actions) self.runAction(sequence) } }
一个简单的显示游戏胜利和失败的页面,仅仅有一个label和一些action。
初始化
var player: SKSpriteNode! //英雄精灵 var lastSpawnTimeInterval: NSTimeInterval! //记录上次时间和更新时间 var lastUpdateTimeInterval: NSTimeInterval! var monstersDestroyed: Int! //记录被消灭的怪兽数量
init(size: CGSize) { super.init(size: size) self.backgroundColor = SKColor(red: 1.0, green:1.0, blue:1.0, alpha:1.0) player = SKSpriteNode(imageNamed: "player") player.position = CGPointMake(self.player.size.width/2, self.frame.size.height/2) self.addChild(player) monstersDestroyed = 0 lastSpawnTimeInterval = 0 lastUpdateTimeInterval = 0 gameLevel.nextLevel() //physics self.physicsWorld.gravity = CGVectorMake(0, 0) self.physicsWorld.contactDelegate = self }
声明了一些属性并在构造过程中进行了赋值。实例化了英雄精灵。
设置了主要的物理引擎属性。
加入怪兽
func addMonster() { var monster = SKSpriteNode(imageNamed: "monster") //location var minY = monster.size.height/2 var maxY = self.frame.size.height - monster.size.height/2 var rangeY = maxY - minY var actualY = arc4random() % rangeY + minY monster.position = CGPointMake(self.frame.size.width + monster.size.width/2, actualY) self.addChild(monster) //physics monster.physicsBody = SKPhysicsBody(rectangleOfSize: monster.size) monster.physicsBody.dynamic = true monster.physicsBody.categoryBitMask = monsterCategory monster.physicsBody.contactTestBitMask = projectileCategory monster.physicsBody.collisionBitMask = 0 //speed var minDuration = 2.0 var maxDuration = 4.0 var rangeDuration = maxDuration - minDuration var actualDuration = arc4random() % rangeDuration + minDuration var actionMove = SKAction.moveTo(CGPointMake(-monster.size.width/2, actualY), duration: actualDuration) var actionMoveDone = SKAction.removeFromParent() var loseAction = SKAction.runBlock({ var reveal = SKTransition.flipHorizontalWithDuration(0.5) var gameOverScene = GameOverScene(size: self.size, won: false) self.view.presentScene(gameOverScene, transition: reveal) }) monster.runAction(SKAction.sequence([actionMove, loseAction, actionMoveDone])) }
对怪物进行了初始化,物理配置,速度设置而且让其行动,假设超出了左边界则判定为游戏失败,假设中途碰到忍者发出的飞镖则会销毁,这部分由碰撞检測来实现,稍后会提到。
加入飞镖
当我们点击屏幕结束的时候,须要发射飞镖来进行攻击。
系统有自带监听方法,和UIKit中的一样。
override func touchesEnded(touches: NSSet!, withEvent event: UIEvent!) { // get touch var touch = touches.anyObject() as UITouch var location = touch.locationInNode(self) //bullet action self.addProjectile(location: location) }
然后是加入子弹的方法
func addProjectile(#location: CGPoint) { var projectile = SKSpriteNode(imageNamed:"projectile") projectile.position = player.position //physics projectile.physicsBody = SKPhysicsBody(circleOfRadius: projectile.size.width/2) projectile.physicsBody.dynamic = true projectile.physicsBody.categoryBitMask = projectileCategory projectile.physicsBody.contactTestBitMask = monsterCategory projectile.physicsBody.collisionBitMask = 0 projectile.physicsBody.usesPreciseCollisionDetection = true var offset = niSub(location, projectile.position) if offset.x < 0 {return} self.addChild(projectile) // direct unit vector var direction = niNormalize(offset) //to screen's edge var shootAmount = niMult(direction, 1000) //now loc var realDest = niAdd(shootAmount, projectile.position) //action var velocity = 480.0/1.0 var realMoveDuration = Double(self.size.width) / velocity var actionMove = SKAction.moveTo(realDest, duration: realMoveDuration) var actionMoveDone = SKAction.removeFromParent() var sequence = SKAction.sequence([actionMove, actionMoveDone]) projectile.runAction(sequence) self.runAction(SKAction.playSoundFileNamed("pew-pew-lei.caf", waitForCompletion: false)) }
跟怪兽一样,我们对飞镖进行了初始化,物理状态配置,然后去依据点击的位置和英雄的位置去确定它的向量方向,好让他開始移动。之后让他在那个方向上去移动。
游戏辅助
在确定方向移动时我们用到了一些自己定义的闭包函数,而且因为Swift是类型安全语言,非常多时候我们不能直接对不同类型的数值进行运算,所以如同在c++中有的一样,Swift也能够进行运算符重载。
// overload @infix func %(lhs: UInt32, rhs: Float) -> Float { return Float(lhs) % Float(rhs) } @infix func %(lhs: UInt32, rhs: Double) -> Double { return Double(lhs) % Double(rhs) } let niAdd = {(a: CGPoint, b: CGPoint) -> CGPoint in CGPointMake(a.x + b.x, a.y + b.y)} let niSub = {(a: CGPoint, b: CGPoint) -> CGPoint in CGPointMake(a.x - b.x, a.y - b.y)} let niMult = {(a: CGPoint, b: Float) -> CGPoint in CGPointMake(a.x * b, a.y * b)} let niLength = {(a: CGPoint) -> CGFloat in CGFloat(sqrt(Double(a.x * a.x + a.y * a.y)))}
// unit vector let niNormalize = {(a : CGPoint) -> CGPoint in var length = niLength(a) return CGPointMake(a.x / length, a.y / length) }
适合的时机加入怪兽
能够注意到我们之前并没有调用加入怪兽的方法,在iOS系统中,每秒的帧数为60,而在SKScene中,刷新帧会有默认的方法update来进行游戏逻辑的编写。
override func update(currentTime: NSTimeInterval) { var timeSinceLast: CFTimeInterval = currentTime - lastSpawnTimeInterval lastUpdateTimeInterval = currentTime if timeSinceLast > 1 { timeSinceLast = Double(gameLevel.toRaw()) / 60.0 lastUpdateTimeInterval = currentTime } self.updateWithTimeSinceLastUpdate(timeSinceLast: timeSinceLast) }
这时我们便能够加入怪兽了
func updateWithTimeSinceLastUpdate(#timeSinceLast: CFTimeInterval) { lastSpawnTimeInterval = lastSpawnTimeInterval + timeSinceLast if lastSpawnTimeInterval > 1 { lastSpawnTimeInterval = 0 self.addMonster() } }
碰撞检測
最后则是须要对碰撞逻辑进行定义。
物理模型有联系时会有代理方法回调。
func didBeginContact(contact: SKPhysicsContact) { var firstBody: SKPhysicsBody! var secondBody: SKPhysicsBody! if (contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask) { firstBody = contact.bodyA; secondBody = contact.bodyB; } else { firstBody = contact.bodyB; secondBody = contact.bodyA; } if (firstBody.categoryBitMask & projectileCategory) != 0 && (secondBody.categoryBitMask & monsterCategory) != 0 { self.didCollide(projectile: firstBody.node as SKSpriteNode, monster: secondBody.node as SKSpriteNode) } }
这时我们希望是怪兽和飞镖碰撞时再进行以下的逻辑
func didCollide(#projectile: SKSpriteNode, monster: SKSpriteNode) { projectile.removeFromParent() monster.removeFromParent() monstersDestroyed = monstersDestroyed + 1 if monstersDestroyed > 30 { var reveal = SKTransition.flipHorizontalWithDuration(0.5) var gameOverScene = GameOverScene(size: self.size, won: true) self.view.presentScene(gameOverScene, transition: reveal) } }
这样整个忍者飞镖怪兽的游戏就完毕了。
以下是游戏截图:
游戏的代码: 点击打开链接
以上是本篇博客所有内容。欢迎指正和讨论。