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我正在构建一个球在 iPad 屏幕内弹跳的游戏。类似于乒乓球游戏。我看到 SKScene 的 SKPhysicsWorld 具有重力属性，并且还控制对象如何相互碰撞。

有什么方法可以自动检测精灵的边缘是否与屏幕的边缘碰撞，所以它可以反弹？还是我需要编写自己的碰撞代码？

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4 回答 4

10

您无需编写太多代码即可使球从屏幕边缘反弹。物理环境可以处理上述所有情况，您只需要以正确的方式实例化精灵。

首先，您必须将场景的物理主体设置为：

self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];

在场景的 .h 文件中创建两个位掩码类别：

static const uint8_t ballCategory = 1;
static const uint8_t wallCategory = 2;

并给场景的物理体一个类别：

self.physicsBody.categoryBitMask = wallCategory;

然后创建你的精灵：

SKSpriteNode *spriteNode = [SKSpriteNode spriteNodeWithImageNamed:@"ball.png"]; 

spriteNode.name = @"ball";

spriteNode.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:25];
spriteNode.position = CGPointMake(10.0,10.0); //or anything you want
spriteNode.physicsBody.dynamic = YES;
spriteNode.physicsBody.affectedByGravity = NO;

spriteNode.physicsBody.categoryBitMask = ballCategory;
spriteNode.physicsBody.collisionBitMask = wallCategory;

spriteNode.physicsBody.restitution = 1.0;
spriteNode.physicsBody.friction = 0.0;
spriteNode.physicsBody.linearDamping = 0.0;
spriteNode.physicsBody.angularDamping = 0.0;

[self addChild:spriteNode];

不要给 spriteNode a [SKAction moveTo: duration:]，而是对它的物理体施加一个脉冲。

CGVector impulse = CGVectorMake(1.0,1.0);
[spriteNode.physicsBody applyImpulse:impulse];

瞧！球会从墙上弹起，没有任何东西可以阻止它。

这是 .h 文件的样子：

#import <SpriteKit/SpriteKit.h>

static const uint8_t ballCategory = 1;
static const uint8_t wallCategory = 2;

@interface BallBounce : SKScene

@end

这就是 .m 文件的样子：

#import "BallBounce.h"

@implementation BallBounce

-(instancetype)initWithSize:(CGSize)size
{
    if (self = [super initWithSize:size])
    {
        self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];
        self.physicsBody.categoryBitMask = wallCategory;

        SKSpriteNode *spriteNode = [SKSpriteNode spriteNodeWithColor:[UIColor greenColor] size:CGSizeMake(50, 50)];

        spriteNode.name = @"ball";

        spriteNode.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:25];
        spriteNode.position = CGPointMake(10.0,10.0); //or anything you want
        spriteNode.physicsBody.dynamic = YES;
        spriteNode.physicsBody.affectedByGravity = NO;

        spriteNode.physicsBody.categoryBitMask = ballCategory;
        spriteNode.physicsBody.collisionBitMask = wallCategory;

        spriteNode.physicsBody.restitution = 1.0;
        spriteNode.physicsBody.friction = 0.0;
        spriteNode.physicsBody.linearDamping = 0.0;
        spriteNode.physicsBody.angularDamping = 0.0;

        [self addChild:spriteNode];

        CGVector impulse = CGVectorMake(100.0,100.0);
        [spriteNode.physicsBody applyImpulse:impulse];

    }

    return self;
}

@end
于 2013-12-05T10:57:05.693 回答
7

你试过设置SKScene的物理体吗

[self setPhysicsBody:[SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame]];  //Physics body of Scene

这应该使您的节点保持在框架内。

W

于 2013-11-10T22:37:25.143 回答
2

这是来自http://www.raywenderlich.com/49721/how-to-create-a-breakout-game-using-spritekit 

    SKPhysicsBody* borderBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];
    // 2 Set physicsBody of scene to borderBody
    self.physicsBody = borderBody;
    // 3 Set the friction of that physicsBody to 0
    self.physicsBody.friction = 0.0f;

    // 1
    SKSpriteNode* ball = [SKSpriteNode spriteNodeWithImageNamed: @"Sphere.png"];
    ball.name = @"ball";
    ball.position = CGPointMake(self.frame.size.width/3, self.frame.size.height/3);
    [self addChild:ball];

    // 2
    ball.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:ball.frame.size.width/2];
    // 3
    ball.physicsBody.friction = 0.0f;
    // 4
    ball.physicsBody.restitution = 1.0f;
    // 5
    ball.physicsBody.linearDamping = 0.0f;
    // 6
    ball.physicsBody.allowsRotation = NO;
    ball.physicsBody.affectedByGravity = NO;

    [ball.physicsBody applyImpulse:CGVectorMake(10.0f, 10.0f)];
于 2014-03-07T05:47:48.580 回答
2

这会将您的节点带入 Swift 的框架中：

self.physicsBody = SKPhysicsBody (edgeLoopFromRect: self.frame)
于 2015-08-10T06:56:02.170 回答