bezier控制点计算

现在精灵在originPoint位置，要沿着弧线走到endPoint位置：

 1   ccBezierConfig by;
 2     by.controlPoint_1 = ccp(-controlX, 0);
 3     by.controlPoint_2 = ccp(-controlX, controlY);
 4     by.endPosition = ccp(0, controlY);
 5     CCBezierBy *bezierBy = CCBezierBy::create(1.0f, by);
 6     
 7     ccBezierConfig to;
 8     to.controlPoint_1 = ccp(originPoint.x-controlX, originPoint.y);
 9     to.controlPoint_2 = ccp(originPoint.x-controlX, endPoint.y);
10     to.endPosition = endPoint;
11     CCBezierTo *bezierTo = CCBezierTo::create(1.0f, to);

by是相对现在的位置

to是绝对位置