SKAction to follow Circle CGPathRef in clockwise direction

问题

My SKSpriteNode follows this path in a counterclockwise direction, how do i make it so it follows the path in a clockwise direction?

Thanks in advance!

    CGPathRef circle = CGPathCreateWithEllipseInRect(CGRectMake(0,0,50,50), NULL);

    SKAction *followTrack = [SKAction followPath:circle asOffset:YES orientToPath:YES duration:5.0];

    SKAction *forever = [SKAction repeatActionForever:followTrack];

    [player2 runAction:forever];

回答1:

Instead of CGPathCreateWithEllipseInRect(), use CGPathCreateMutable() and CGPathAddArc() to create the circle path and use the clockwise parameter to control the direction.

Untested code:

CGMutablePathRef circle = CGPathCreateMutable();
CGPathAddArc(circle, NULL, 25, 25, 25, 0, 2*M_PI, true);
CGPathCloseSubpath(circle);

回答2:

From Martin's answer a few changes cause the object to start and end at the same place:

In Objective C

CGMutablePathRef circle = CGPathCreateMutable();
CGPathAddArc(circle, NULL, -25, 0, 25, 0, 2*M_PI, true);
CGPathCloseSubpath(circle);

In swift

let path = CGPathCreateMutable()
CGPathAddArc(path, nil, -25, 0, 25, 0, CGFloat(2.0 * M_PI), true)
CGPathCloseSubpath(path)

来源：https://stackoverflow.com/questions/22746843/skaction-to-follow-circle-cgpathref-in-clockwise-direction