Generating truck objects from lists of points

[twitchyliquid64]

Hi!

I'm working on a 2d constraint-solving CAD, and would like to implement the ability to export a linear/lathe extrusion of the drawing as an STL or STEP file. Truck seems like the best library for the job as far as I can tell.

Can you help me work out how to do this?

I think I need to create a Wire to represent the boundary geometry, creates two faces from this wire for the top and bottom faces, and then glue them together somehow, perhaps glue_at_boundaries ? And then presumably i need to use boolean operations to cut out interior geometry?

Lathe extrusion might be easier, if I can create a Wire maybe I can use rsweep ?

[twitchyliquid64]

I ... think I got it working? could it be?

https://github.com/twitchyliquid64/liquid-cad/commit/a0b5fb50946e002efc4c5f3284570c7cec1861c7#diff-1d4b34bc50dcd41fc559b9563fbba91dfab991671496865a28cee406e0e976ef

PrusaSlicer says my generate STL has a number of errors - I'm not sure if there is a bug in truck or I'm doing something incorrect.

[MattFerraro]

Hello,

Are you familiar with tsweep? That plus rsweep should get you most of the way there. The key is to sweep a face, not a wire, so that the outcome is a solid, not a shell.

Cheers, Matt

[twitchyliquid64]

Thanks!

Yepp I'm sweeping a face to make a solid, the remaining issue is just that truck is producing an STL which PrusaSlicer says has errors, but I can file a separate issue for that!

[twitchyliquid64]

For the sake of posterity, here's how I did it:

1. Make a Wire by collecting a Vec of lines which connect your points to form a closed loop (you could also use the other builder methods here, no need for everything to be a straight line)

   
   let lines = vec![
   builder::line(builder::vertex(Point3::new(1.0, 0.0, 0.0)), builder::vertex(Point3::new(2.0, 0.0, 0.0))),
   builder::line(builder::vertex(Point3::new(2.0, 0.0, 0.0)), builder::vertex(Point3::new(2.0, 3.0, 0.0))),
   builder::line(builder::vertex(Point3::new(2.0, 3.0, 0.0)), builder::vertex(Point3::new(1.0, 0.0, 0.0))),
   ];
   // NOTE: Don't actually create duplicate vertex objects, reuse ones that point to the same point

let wire: Wire = lines.into();

2. Convert into a face

```rust
let face = builder::try_attach_plane(&wires).unwrap();

3. Sweep to form a solid object:

let solid = builder::tsweep(&face, height * Vector3::unit_z());