Morphing Sweeps

open OCADml
open OSCADml

While Mesh.sweep and it's derived functions are useful for sweeping fixed polygons with holes, as shown in the rounded sweeps demo, the Mesh.morphing_sweep family provides a means to do so with different shapes at the beginning and end.

let () =
  let path =
    let control =
      V3.[ v 0. 0. 2.; v 0. 20. 20.; v 40. 20. 10.; v 30. 0. 10. ]
      |> Path3.quaternion (Quaternion.make (v3 1. 1. 0.) (Float.pi /. -5.))
    Bezier3.curve ~fn:80 @@ Bezier3.of_path ~size:(`Flat (`Rel 0.3)) control
  and caps =
    Mesh.Cap.(capped ~bot:(round @@ circ (`Radius 0.5)) ~top:(round @@ circ (`Radius 0.5)))
  and a = Poly2.ring ~fn:5 ~thickness:(v2 2.5 2.5) (v2 6. 6.)
  and b = Poly2.ring ~fn:80 ~thickness:(v2 2. 2.) (v2 4. 4.) in
  Mesh.path_morph ~refine:2 ~caps ~path ~outer_map:`Tangent a b
  |> Scad.of_mesh
  |> Scad.to_file "tangent_morph_sweep.scad"

Similar to the ?scale_ez and ?twist_ez parameters on Path3.to_transforms and those that make use of it, such as Mesh.morph, the morphing sweep functions in the Mesh module expose ?ez, which offers the same style of bezier easing (see Easing) for morphs.

let scad =
  let top =
      ~ez:(v2 0.42 0., v2 1. 1.)
      (Poly2.ring ~fn:5 ~thickness:(v2 0.5 0.5) (v2 4. 4.))
      (Poly2.ring ~fn:80 ~thickness:(v2 0.2 0.2) (v2 1. 1.))
    |> Scad.of_mesh
  Scad.(add (ztrans 2. top) (ztrans (-2.) @@ xrot Float.pi top))

As the generated mesh contains quite a large number of points due to the large number of slices and the resolution of the inner ring (and the duplication) of the shape (megabytes), we'll take advantage of the include trick provided by the optional ?incl parameter to Scad.to_file. This will produce a pair of .scad scripts, one named "incl_eased_morph.scad", and another named "eased_morph.scad" that simply includes it. By loading the later into OpenSCAD rather than the former, we can avoid the sluggishness that can result when the editor attempts to handle large files.

let () = Scad.to_file ~incl:true "eased_morph.scad" scad