# Geometry Nodes: How to set curve line rotation to another curve's tangent?

Description: In this scene, I want to create a series of vertical planes along a horizontal curve circle. These planes must be created using a vertical curve line node. They were turned into 2D planes with a 'curve to mesh' node, using a curve line node along the X-axis as profile.

The problem: I am trying to get these planes to face inwards. They need to be oriented to the tangent of the curve circle (annotated in the 3D view). How do I achieve this?

Curve to Points node gives you Rotation output exactly for that purpose - just connect it to the instance rotation:

If this doesn't align the instances properly, you can either:

• add an intermediary node Rotate Euler,
• (better) just modify the Direction of the Curve Line.

If this still doesn't work for some reason, you could e.g. take the cross product (Vector Math) of node of the tangent and e.g. $$<0, 0, 1>$$ vector, and pass that to Align Euler to Vector node, to obtain a rotation aligned with Z axis…

You can also chain two Align Euler to Vectors, like I've done here:

• Strangely, whenever the planes are pointed straight up, they become solid gray and lose their rotation. However, any other orientation works fine. Here's some screenshots: imgur.com/a/tskWy9o Jul 6, 2023 at 21:53
• @Thomas Gimbal Lock perhaps. Jul 7, 2023 at 7:41