Offset curve on grasshopper

Hello I’m trying to make a planar truss on a surface that’s tilted. I started with contours n then offset the contours to get the truss shape but the issue I’m facing is when I use the offset command n set the correct plane, the offset of one plane comes out how I want it ( negative in the z direction) but for the rest of the surfaces the offset line gones in positive z direction. I tried flip and negative but it dint work.

wouldn’t you want the plane of the Truss? with branches that match with your contours and use that to offset truss geometry .

Please don’t duplicate posts: Offset option

See here how to ask questions: How to ask effective questions

You could at the very least upload your file with relevant geometry internalized.