CcsPrite跟随一系列cgPoints

为什么要编写自己的tick方法?你为什么不使用内置的 CCMoveTo 方法?

(void) gotoNextWayPoint {
    // You would need to code these functions:
    CGPoint point1 = [self popCurrentWayPoint];
    CGPoint point2 = [self getCurrentWayPoint];

    // Calculate distance from last way point to next way point
    CGFloat dx = point2.x - point1.x;
    CGFloat dy = point2.y - point1.y;
    float distance = sqrt( dx*dx + dy*dy );

    // Calculate angle of segment
    float angle = atan2(dy, dx);

    // Rotate sprite to angle of next segment
    // You could also do this as part of the sequence (or CCSpawn actually) below
    // gradually as it approaches the next way point, but you would need the
    // angle of the line between the next and next next way point
    [mySprite setRotation: angle];

    CCTime segmentDuration = distance/speed;

    // Animate this segment, and afterward, call this function again
    CCAction *myAction = [CCSequence actions: 
          [CCMoveTo actionWithDuration: segmentDuration position: nextWayPoint], 
          [CCCallFunc actionWithTarget: self selector: @selector(gotoNextWayPoint)],
          nil];

    [mySprite runAction: myAction];
}