swift & Spritekit : Creation of a slope

Question

我正在尝试在 2D 游戏中创建斜坡。这个斜坡应该有一个 X 度。当现在一个球“滚过”这个斜坡时。这个坡度的效果应该改变，然后球的行为因此向后滚动，向前滚动或在其他地方初始化倾斜度。我认为我可以使用具有物理 body 的 SKSpritenode 来实现这一点，并且当球滚动(“碰撞”)时效果应该受到球的影响，但我无法实现这一点。

我怎样才能做到这一点？

最好的问候，

克里斯

Answer 1

如果我对你的问题的理解正确，你正在寻找斜坡，以便在球向上或向下移动时对球产生物理影响。

请看下面的示例项目(该项目处于横向模式并且 show physics 设置为 YES)。

#import "GameScene.h"

typedef NS_OPTIONS(uint32_t, Level1PhysicsCategory) {
    CategoryBall  = 1 << 0,
    CategoryFloor0  = 1 << 1,
};

@implementation GameScene {
    SKSpriteNode *ballNode;
}

-(void)didMoveToView:(SKView *)view {
    self.backgroundColor = [SKColor whiteColor];

    // create slope floor
    SKSpriteNode *myNode0 = [SKSpriteNode spriteNodeWithColor:[SKColor clearColor] size:CGSizeMake(200, 100)];
    myNode0.position = CGPointMake(500,300);
    myNode0.zPosition = 100;
    CGMutablePathRef trianglePath = CGPathCreateMutable();
    CGPathMoveToPoint(trianglePath, nil, -myNode0.size.width/2, myNode0.size.height/2);
    CGPathAddLineToPoint(trianglePath, nil, myNode0.size.width/2, -myNode0.size.height/2);
    CGPathAddLineToPoint(trianglePath, nil, -myNode0.size.width/2, -myNode0.size.height/2);
    CGPathAddLineToPoint(trianglePath, nil, -myNode0.size.width/2, myNode0.size.height/2);
    myNode0.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:trianglePath];
    myNode0.physicsBody.dynamic = NO;
    myNode0.physicsBody.restitution = 0;
    myNode0.physicsBody.friction = 0.0;
    myNode0.physicsBody.categoryBitMask = CategoryFloor0;
    myNode0.physicsBody.collisionBitMask = CategoryBall;
    CGPathRelease(trianglePath);
    [self addChild:myNode0];

    // create top floor
    SKSpriteNode *myNode1 = [SKSpriteNode spriteNodeWithColor:[SKColor clearColor] size:CGSizeMake(300, 5)];
    myNode1.position = CGPointMake(250,348);
    myNode1.zPosition = 100;
    myNode1.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(300, 5)];
    myNode1.physicsBody.dynamic = NO;
    myNode1.physicsBody.restitution = 0;
    myNode1.physicsBody.friction = 0.0;
    myNode1.physicsBody.categoryBitMask = CategoryFloor0;
    myNode1.physicsBody.collisionBitMask = CategoryBall;
    [self addChild:myNode1];

    // create bottom floor
    SKSpriteNode *myNode2 = [SKSpriteNode spriteNodeWithColor:[SKColor clearColor] size:CGSizeMake(300, 5)];
    myNode2.position = CGPointMake(750,248);
    myNode2.zPosition = 100;
    myNode2.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(300, 5)];
    myNode2.physicsBody.dynamic = NO;
    myNode2.physicsBody.restitution = 0;
    myNode2.physicsBody.friction = 0.0;
    myNode2.physicsBody.categoryBitMask = CategoryFloor0;
    myNode2.physicsBody.collisionBitMask = CategoryBall;
    [self addChild:myNode2];

    // create ball
    ballNode = [SKSpriteNode spriteNodeWithColor:[SKColor clearColor] size:CGSizeMake(20, 20)];
    ballNode.position = CGPointMake(770,300);
    ballNode.zPosition = 100;
    ballNode.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:10];
    ballNode.physicsBody.dynamic = YES;
    ballNode.physicsBody.restitution = 0;
    ballNode.physicsBody.friction = 0.0;
    ballNode.physicsBody.categoryBitMask = CategoryBall;
    ballNode.physicsBody.collisionBitMask = CategoryFloor0;
    [self addChild:ballNode];
}

-(void)update:(CFTimeInterval)currentTime {

    // check if ball has fallen off screen
    // if yes, put ball back in place
    if(ballNode.position.y < 0) {
        ballNode.physicsBody.velocity = CGVectorMake(0, 0);
        ballNode.position = CGPointMake(770, 300);
    }
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    // change the dx velocity to apply more or less force to the ball
    [ballNode.physicsBody applyImpulse:CGVectorMake(-7, 0)];
}