How to create perfectly parallel offset splines?

I know this is going to sound weird but

  1. Get spline data
  2. Sample spline (any mode)
  3. Create Spline
  4. Sample Spline (subdivision with 0 per segment)
  5. now run 2 outputs ( 1 for each spline)
  6. on each output use a Transform Points node and offset the Y by the amount desired.
  7. create spline
  8. spawn meshes or whatever your final steps are.

As weird as it is. steps 1-4 are 100% necessary for some reason. even if they seem redundant.

while this isn’t 100% perfect parallel it should be close enough for most use-cases. resampling it with 0 sudivisions will give you flush ends. altho the curves may have small gaps which can be fixed by slightly overlapping the meshes.

if you need 100% perfect parallels this post goes over that. but it’s a lot of math, and a lot more overhead, manually placing each point in the point data of the 2nd spline.
Parallel Splines - Programming & Scripting / Blueprint - Epic Developer Community Forums