iOS7 SKScene如何使精灵弹出屏幕的边缘？

Question

我正在制作一个在iPad屏幕上弹跳球的游戏。类似于乒乓游戏。我看到SKScene的SKPhysicsWorld具有重力特性，并且控制着物体如何相互碰撞。

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

Answer 1

你不需要写太多的代码来使球从屏幕边缘弹出。物理环境可以处理以上所有的事情，您只需要以正确的方式实例化这些精灵。

首先，您必须将场景的physicsBody设置为这样：

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;

并给现场的物理身体一个类别：

self.physicsBody.categoryBitMask = wallCategory;

然后创建你的雪碧：

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];

与其给spriteNode一个[SKAction moveTo: duration:]，不如对它的物理体施加一种冲动。

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

然后瞧！球将在没有任何东西阻挡的情况下从墙壁上反弹。

.h文件应该是这样的：

#import <SpriteKit/SpriteKit.h>

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

@interface BallBounce : SKScene

@end

.m文件应该是这样的：

#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

Answer 2

你试过设置SKScene的物理体吗？

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

这应该使您的节点处于帧内。

W

Answer 3

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

    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)];