I want the srf in the guided direction, so the extracted point can all be the same order as the guide.
The easiest way to do this in GH is definitely through the “Flip” component,
While the result “true” tells the opposite, the plane result isn’t changed like guide srf.
And is there any approach that could do the same thing in RhinoCommon?
I’m not entirely sure what you want, but when if you flip your surface based on the guide surface, that doesn’t always mean the resulting surface follows the guide surface’s plane orientation. Flipwould just reference the normal direction of the guide surface…