问题描述
我正在使用 Sprite Kit 制作 2D 游戏,我需要添加一种方法来在每 50 点后加速游戏.
I am making a 2D game with Sprite Kit and I need to add a method to speed up the game after every 50 points.
我制定了一种方法,可以根据需要增加速度,但是每增加 50 个点,我就必须复制、粘贴和调整更新方法中的 if 语句.
I worked out a method that adds the speed as wanted, but I have to copy, paste and adjust an if-statement in the update method for every additional 50 points.
我的解决方案的另一个问题是我必须在加速后立即增加我的积分,因为如果不是,游戏完全加速,虽然我不知道为什么.
Another problem with my solution is that I have to give my points an increment right after speeding it up, because if not the game speeds up completely, though I don't know why.
这是我目前的解决方案:
Here is my solution so far:
// inside the update method
// points are added when an enemy is destroyed
// pointSpeed is the float variable that is used to change positions
if (points == 4) {
pointSpeed++;
points++;
}
if (points == 8) {
pointSpeed++;
points++;
}
if (points == 12) {
pointSpeed++;
points++;
}
我想实现此功能,而不必被迫手动完成所有增量,也不想在没有积分增量的情况下加快游戏速度.
I would like to implement this feature without being forced to do all increments manually and without the game speeding up without points increments.
推荐答案
Swift way
您可以使用 didSet 属性观察器根据当前分数更改游戏速度:
You can use didSet property observer to change the game speed based on the current score:
import SpriteKit
class GameScene: SKScene {
var score:Int = 0 {
didSet{
if score % 10 == 0 {
gameSpeed += 0.5
}
label.text = "Score : (score), Speed : (gameSpeed)"
}
}
var gameSpeed:Double = 1.0
var label:SKLabelNode = SKLabelNode(fontNamed: "ArialMT")
override func didMoveToView(view: SKView) {
/* Setup your scene here */
label.text = "Score : (score), Speed : (gameSpeed)"
label.position = CGPoint(x: CGRectGetMidX(frame), y: CGRectGetMidX(frame))
label.fontSize = 18
addChild(label)
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
score++
}
}
来自文档:
didSet 在新值存储后立即调用.
因此,在设置新分数后,您应该立即更新 gameSpeed
变量.
So, immediately after the new score is set, you should update the gameSpeed
variable.
Objective-C 方式
在 Objective-C 中,没有这样的东西可以提供与 Swift 的 didSet 和 willSet 属性观察器完全相同的行为.但是还有另一种方法,例如您可以覆盖分数的设置器,如下所示:
In Objective-C there is no such a thing which can provide the exact same behaviour like Swift's didSet and willSet property observers. But there are another ways, for example you can override a score's setter, like this:
#import "GameScene.h"
@interface GameScene()
@property(nonatomic, strong) SKLabelNode *label;
@property(nonatomic, assign) NSUInteger score;
@property(nonatomic, assign) double gameSpeed;
@end
@implementation GameScene
-(instancetype)initWithCoder:(NSCoder *)aDecoder{
NSLog(@"Scene's initWithSize: called");
if(self = [super initWithCoder:aDecoder]){
/*
Instance variables in Obj-C should be used only while initialization, deallocation or when overriding accessor methods.
Otherwise, you should use accessor methods (eg. through properties).
*/
_gameSpeed = 1;
_score = 0;
NSLog(@"Variables initialized successfully");
}
return self;
}
-(void)didMoveToView:(SKView *)view {
self.label = [SKLabelNode labelNodeWithFontNamed:@"ArialMT"];
self.label.fontSize = 18;
self.label.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
self.label.text = [NSString stringWithFormat:@"Score : %lu, Speed %f", self.score, self.gameSpeed];
[self addChild:self.label];
}
//Overriding an actual setter, so when score is changed, the game speed will change accordingly
-(void)setScore:(NSUInteger)score{
/*
Make sure that you don't do assigment like this, self.score = score, but rather _score = score
because self.score = somevalue, is an actual setter call - [self setScore:score]; and it will create an infinite recursive call.
*/
_score = score;
if(_score % 10 == 0){
self.gameSpeed += 0.5;
}
// Here, it is safe to to write something like self.score, because you call the getter.
self.label.text = [NSString stringWithFormat:@"Score : %lu, Speed %f", self.score, self.gameSpeed];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
self.score++;
}
@end
或者,我想,你可以使用 KVO,但对于您的示例,由于简单,您可以只覆盖一个 setter.或者,也许您可以创建一个自定义方法来增加分数,处理 gameSpeed 的更新逻辑,并在必要时更新速度:
Or, I guess, you can do the same using KVO, but for your example because of simplicity, you can just override a setter. Or maybe you could just make a custom method which will increase the score, handle the gameSpeed's updating logic, and update the speed if necessary:
//Whenever the player scores, you will do this
[self updateScore: score];
因此,与此相比,您将有一个额外的方法定义,必须在玩家得分时调用该方法(假设得分的 setter 已被覆盖):
So, you will have an additional method definition, which must be called when player scores, in compare to this (assuming that score's setter is overridden):
self.score = someScore;
这完全取决于您.
希望这是有道理的,它会有所帮助!
Hope this make sense and it helps!
我已经将 initWithSize:
更改为 initWithCoder
,因为从 sks 加载场景时不会调用 initWithSize
,这可能是你是怎么做的,因为在 Xcode 7 场景中,默认情况下是从 .sks 文件加载的.
I've changed the initWithSize:
to initWithCoder
, because initWithSize
is not called when the scene is loaded from sks, which is probably how you are doing it, due to fact that in Xcode 7 scene is loaded by default from .sks file.
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