计算两点中的中点

//计算两点之间的中点
AcGePoint3d MidPoint(AcGePoint3d pt1, AcGePoint3d pt2)
{
AcGePoint3d pt;
pt.x = (pt1.x + pt2.x)/2;
pt.y = (pt1.y + pt2.y)/2;
pt.z = (pt1.z + pt2.z)/2;
return pt;
}