# Trouble with a simple geometrical problem

Hi everyone,

I am having some trouble transporting this logic into 3D. The idea is that depending on the curve’s direction, a concave or convex curve is generated.

If parallel to Y axis its concave.
If parallel to X axis its convex.

To achieve this I used the absolute function.

But in 3D space, the vector is decomposed into word coordinates instead of the specific plane needed, and it does not work.

The attached def contains both the 2D version and the 3D version.

Thanks for any help.

Flip Curve by Rotation.gh (21.8 KB)

I don’t think “convex” and “concave” are used correctly here. Looking at your file now, but I’m very confused after reading the question.

You can set up a Plane to Plane transformation (from WorldXY to your custom plane) and then transform your vector. Convert it into absolute components, then transform it back with the opposite transformation.

Im afraid I am not following David, could you provide an example please? Thank you.

I think maybe you missed the reason I used Perp Frames and Point Oriented in my reply on this subject three days ago? You need more than 2D algorithms in a 3D space.

Graph_Mapper_Curves_2018Mar27a.gh (42.5 KB)

Here it is again with Align Plane, which looks more consistent but has an issue at one end:

Graph_Mapper_Curves_2018Mar30a.gh (44.2 KB)

Various orientations available by connecting to ‘U’ and/or ‘V’ and/or ‘W’ inputs to Point Oriented, and optionally using the expression “-x” on each one.

Thank you Jospeh. I did not miss it. Both your responses helped a lot with that particular issue.

I don’t see how that is relevant for this specific question though.

Oh well. Looks and sounds like the same question to me.

Nono, maybe you undestood better what David said? I couldn’t follow what he suggested.

Okay I have refined the definition and I tried to implement what David suggested, but something must be wrong because it isnt working…

Flip Curve by Rotation2.0.gh (28.4 KB)