This is probably a stupid question, but now I have tried so many ways to draw geometry starting from rotated planes in GrassHopper, but unless the component doesn’t have an explicit Plane input (or “Base”), the geometry will of course not align to the plane (only to the plane’s position in World, if starting from the Plane as a “point”).

I tried using vectors as well. But my attempts ends up with distortions of the angles of the geometry which I want to be following the transformed Plane when I tilt or rotate the Plane.

What has succeeded so far is straight lines based on Plane Normals, but if I rotate them, and then flip or rotate the plane, the lines are not rotated properly (again, the angles gets “distorted” by combined plane angles).

Obviously I don’t understand Planes in GH and how they are meant to be used. Obviously they are nothing like the Construction Planes in Rhino Viewports.

**Q**: So what is the basic approach for drawing, lets say, a line, on a plane being rotated and/or flipped and… so that that line is also rotated & flipped when the plane is flipped. Do I have to make two rotations - one for the plane an one for the geometry? If so, why then bother rotating the plane in the first place?

I must be missing something fundamental here, probably thinking in the wrong order. Like, must each GH object be explicitly rotated & flipped, and I cannot assume that geometry would follow the transformations of a plane? < scratching head >

// Rolf

**Edit**: Example picture: the two planes are at each end of a line (not shown) and are rotated. The green line (y+) was drawn starting from the lower plane (with a Point component based on that plane), but is not rotated togerther with the plane :