Re:Show HN: 3D Meshes of Signed Distance Functions in Python
by bhouston on Tuesday February 16, 2021 @09:41PM
(#26162012)
Take the spatial derivative for the normals? Runga-kutta methods work wonders for that: https://en.m.wikipedia.org/wiki/Runge–Kutta_methods That works well if they are true signed distance.
Re:Show HN: 3D Meshes of Signed Distance Functions in Python
by user-the-name on Wednesday February 17, 2021 @05:01AM
(#26164708)
Since you have a distance, you could fairly easily implement dual contouring, I think?
Re:Show HN: 3D Meshes of Signed Distance Functions in Python
by andybak on Wednesday February 17, 2021 @09:44AM
(#26166795)
Or Surface Nets. Nice compromise of speed and quality. Marching cubes needs a lot of resolution and it's imperfections are especially ugly my eyes.
Maybe mesh resolution isn't a problem for 3D printing. But if 3D printing is the main goal why bother with a mesh? Just go straight to voxels that can be fed directly to the printer.
Re:Show HN: 3D Meshes of Signed Distance Functions in Python
by user-the-name on Wednesday February 17, 2021 @10:18AM
(#26167238)
The printer does not use voxels, it uses G-codes, which are tool paths for the print head.
Re:Show HN: 3D Meshes of Signed Distance Functions in Python
by tdotuos on Wednesday February 24, 2021 @11:49PM
(#26259813)
True for FDM, but for SLA you have the potential rendering a direct slice of the SDF.
Re:Show HN: 3D Meshes of Signed Distance Functions in Python
by andybak on Wednesday February 17, 2021 @12:42PM
(#26169089)
OK. But a voxel representation has to be a closer match than a mesh. I guess overhang, solidity etc still need to be calculated and dealt with. Which is non-trivial.
Is it that "mesh to G-code" libraries are more mature than "voxel to G-code"?
I'm not doing anything special for sharp geometry. For now you just need to use sufficient resolution until it looks "good enough." Normals are just based on the triangle normals.