沿触摸路径移动对象

Question

我有一个笔划圆路径和一个小填充圆路径，并且我想沿笔划圆路径沿触摸方向移动该小圆，该小圆不应位于笔划圆之外。我怎样才能做到这一点 ？请帮助我

Answer 1

您的触摸可能不在您的圈子路径之外。要提供对象在圆上的位置，可以进行下一个：

    find position of touch against circle center
dx = touch.x - center.x
dy = touch.y - center.y
    find distance from the center
dist = sqrt(dx*dx +dy*dy)
     make new position at the same disraction form center but at circle radius distance
newx = center.x + radius * dx / dist
newy = center.y + radius * dy / dist