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First i'd like to say thanks to every users on this website because i'm always finding solutions here and it's sooo helpful !

I'm trying to make a game like Xonix, Bix or Jezzball with SpriteKit. Anyway, i have a ball bouncing against walls, and i'm trying to make obstacles where it can't go, those obstacles are made from CGPathref (the user makes it with its movements)

I'm using bodyWithPolygonFromPath to create the physicsbody of the skspritenode, it's working, but not always. I've downloaded YMCPhysicsDebugger to see the content of the body, and in every case, it's good, but i've seen that when i have more than 4 points on the CGPath, the ball does not collide against the whole of the body, it only collides against a smaller zone.. I've tried and searched a lot without any results.. I've tried to make the points of CGPath counterclockwise, it doesn't work as well, even in the other side..

I'm copying you the code for the creation of SKSpriteNode, but i doubt it will be useful, i think the problem is with my points, maybe i need more explanations on how the physicsbody works with a polygon

SKSpriteNode *zone = [SKSpriteNode spriteNodeWithColor:[UIColor redColor] size:CGSizeMake(50, 50)];
zone.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path.CGPath]; // 1
zone.physicsBody.friction = 0.0f;
zone.physicsBody.restitution = 0.0f;
zone.physicsBody.linearDamping = 0.0f;
zone.physicsBody.allowsRotation = NO;
zone.physicsBody.categoryBitMask = wallsCategory;
zone.physicsBody.dynamic = NO; // 2
[self addChild:zone];

Here are two pictures of my "game", the first one works, the ball bounces right back against it. The second one is not working like it should, only the upper part is detected for collision.

http://hpics.li/86a69e2

http://hpics.li/e16d18e

I've also tried to detect when the ball enters an obstacle in the update function to manually make it bounce against it, but of course, it's not really working. Plus my math studies are not that good lol

for(SKSpriteNode *zone in zonesTab) 
{
    UIBezierPath *path = [zoneesTab objectAtIndex:i]; // Array of UIBezierPath for the obstacles
    if(CGPathContainsPoint(path.CGPath, NULL, ball.frame.origin, FALSE)) 
    {
        ball.physicsBody.velocity=CGVectorMake(ball.physicsBody.velocity.dx*-1, ball.physicsBody.velocity.dy*-1);
        NSLog(@"Touches iT");
    }
    i++;

}

I've also thought about making several SKSpriteNode everytime a CGPath has more than 4 points, but i don't really know how to do that in mathematics..

Anyway, that's a long post, I hope some of you will read it all and understand it all (sorry for my english, i'm french!) and most of all, will be able to help me !!

Thank you very much

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1 回答 1

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第一个屏幕截图中的形状是凸的，但第二个屏幕截图中的形状是凹的。

物理多边形形状需要凸出才能正常工作。您可以执行以下两项操作之一：

  • 创建两个节点和两个实体，它们各自的形状是凸形的，但它们一起形成凹形。这些物体可以是动态的。您可能希望将它们设置为静态或使用刚性距离接头将它们连接在一起，或者确保它们不会分开。
  • 使用bodyWithEdgeLoopFromPath:或bodyWithEdgeChainFromPath:能够创建凹形碰撞形状。这些物体不会是动态的，也无法自行移动，但它们是具有静态运动场的任意碰撞形状的完美解决方案。
于 2014-01-15T17:28:49.020 回答