centerM cmds d2m d2mgs displayMmToModel displayMmToModel displayMmToModel displayMmToModelBox displayMmToModelBox distanceM dragging gestureState gestureType lastPt lastPtM MgMotion point point2 point2M pointM pressDrag startCenterM startDistanceM startPt startPt2 startPt2M startPtM switchGesture velocity view

startPt2M Point2d MgMotion::startPt2M 双指按下的第二个手指位置，模型坐标