Loft sequence for polylines

Hi everyone,

Problem 1:
I have tried to create a loft using 3 polyline curves. The problem I am having is sequencing the curves correctly. The result comes out in a very different order. Is there any way to modify this order manually?

I’ve used the merge component but it won’t work.

Problem 2:
Is there a way to align the normals of all the curves as well(maybe using a directional vector)?
When I used this for 3 curves, it sometimes twists the loft or turns it upside down. The other times, the vertices don’t match. I tried using shift list for changing the point order manually, but that beats the point of the parametric program.
If it helps, I am only using rectangles as polylines.

I have attached the gh file and some images. Please do let me know

Thanks! (4.1 KB)

For reference, I have already checked:

There are three separate issues with this model:

  1. The sequence problem is caused by each of your curves having a different tree/branch structure, as shown in the “tree mess” panel. Flattening the inputs to Merge fixes that. Flattening the output (or input to Loft) is too late.
  2. The direction of the curves aren’t all the same so I added Flip Curve using the first curve as a guide.
  3. The seam (start/end point) on the bottom curve doesn’t match the others so I shifted it (white group). (12.0 KB)

Thank you Joseph for your quick reply. That does solve problem 1 for me.

Now for problem 2:
Just wanted to know if there is a way to solve the flip curve situation without having to do it manually every time. This is a problem since I use this routine multiple time and need to make the shift list and/or flip curve every time the loft doesn’t work out

For now, I am deconstructing each corresponding point in each curve to have the curves ‘constructed’ in a similar manner so that the loft follows through.

Is there any method by which we can orient the curves (direction and corresponding point) without this much complication?

Thank you!

Just wanted to know if there is a way to solve the flip curve situation without having to do it manually every time.

Flip curve component is not manual. Just plug one guide curve and then the rest of the curves will follow that.

For Seam, in my opinion you should be conscious of the seam in the first place, but if not then Pufferfish has an Align Curve Seams component which is iterative (closest point methods won’t always give great result, iteration is the way to go, the Pufferfish one will also allow you the option to snap re-aligned seams to corners, which is probably what you want for polylines).

Lastly, in loft options there is a handy “Align” option which can usually fix some of this stuff.

In the end though, it would be better to generate these polylines correctly in the first place, being preventative is usually better practice than band-aides.

Thank you Michael, your solution seems to be working. Will keep you posted on any new findings.

You are right about the point where you said that I should control the way the curve is created, but it is a bit hard to accomplish in my current scenario.
I am extracting a surface from a brep using deconstruct brep. I am then getting all the vertices and trying to reorder these to get uniformly defined polylines. This is what makes it hard to define the construction of the polyline