On mesh to curve geo node, how to get a seperate spline per edge

Question

I am working on a roof project and want to automate the placement of ridge tiles on selected edges of a roof. Selecting the appropriate edges I was able to master. Now, ridge tiles require a direction of placement (downwards) and therefore I want to use curves as the point givers for the instances on points node.

My problem now is: After having selected the appropriate edges of the roof (only downwards ones) the resulting curve may consist of single straight splines per edge but also of splines which represent two or more edges. Now, how can I get a spline per edge?

In the end I want all the splines to have the direction from highest to lowest vertex per edge.

Answer 1

To convert the edges of the roof into curves whose indices run from top to bottom, you can use the following setup:

Here, I first filter out the edges from the base mesh that run horizontally. I split the remaining edges at the vertices and convert them into curves.

Finally, I check whether the tangents of the curves point upwards or downwards, and reverse the direction of the curves selected in this way.

_{(Blender 3.2+)}