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I'm not sure I understand your comment; OpenSCAD has functions like sphere(), cylinder(), etc. Most OpenSCAD models I have seen are built up primarily from sol

by 7bees 6mo ago

I'm not sure I understand your comment; OpenSCAD has functions like sphere(), cylinder(), etc. Most OpenSCAD models I have seen are built up primarily from solid primitives combined using boolean operations, just as you describe for the other tools. https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Manual/Primitive_Solids&stable=1 https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man...

seltzered_ 6mo ago
Theres a better description of the differences here: https://build123d.readthedocs.io/en/latest/OpenSCAD.html#transitioning-from-openscad https://build123d.readthedocs.io/en/latest/OpenSCAD.html#tra... Some of the differences may be in when you are trying to reference a face/edge to build off of, not just about the primitive function being used.
Doxin 6mo ago
OpenSCAD works natively with triangle meshes. sphere() will create a spherical triangle mesh. These libraries on the other hand can natively represent a sphere for instance. This means that during CAD-ing you don't need to worry about resolution, that's a consideration for export only.
- flowerbreeze 6mo ago
  Do you mean that OpenScad performs boolean/other operations on triangle meshes, but these libraries don't until output? So they might instead use curved surfaces/edges etc as outputs for operations and only convert to triangles for output or export at the very end?
  - Doxin 6mo ago
    yes, exactly.
  - Karliss 6mo ago
    It isn't even necessary to create triangle meshes during export. You can export as step files. It is a commonly used brep based file format supported by almost any "proper" CAD software. Triangle mesh based modelers can't easily export good step files because they don't operate at that level of abstraction.
  - rowanG077 6mo ago
    In professional CAD systems, geometry is not stored as triangle meshes but as mathematically defined surfaces (such as parametric and NURBS surfaces). Triangle meshes are only generated as approximations for rendering. This is analogous to vector graphics (SVG/EPS) versus raster images (PNG/JPG). Any serious manufacturing will work require a STEP (or something equivalent) which stores these parametric surfaces rather than a mesh.
ur-whale 6mo ago
> I'm not sure I understand your comment Try to do the following with OpenSCAD: 1. put a sphere and a torus somewhat close to each other 2. find the shortest segment between the two surfaces 3. place an infinite cylinder whose axis is aligned with the segment you just found 4. fillet the cylinder with both the torus and the sphere along its intersection curve with each surface This is very, very hard to do with OpenSCAD.

by 7bees 6mo ago

seltzered_ 6mo ago

Theres a better description of the differences here: https://build123d.readthedocs.io/en/latest/OpenSCAD.html#transitioning-from-openscad https://build123d.readthedocs.io/en/latest/OpenSCAD.html#tra... Some of the differences may be in when you are trying to reference a face/edge to build off of, not just about the primitive function being used.

Doxin 6mo ago

OpenSCAD works natively with triangle meshes. sphere() will create a spherical triangle mesh. These libraries on the other hand can natively represent a sphere for instance. This means that during CAD-ing you don't need to worry about resolution, that's a consideration for export only.

flowerbreeze 6mo ago
Do you mean that OpenScad performs boolean/other operations on triangle meshes, but these libraries don't until output? So they might instead use curved surfaces/edges etc as outputs for operations and only convert to triangles for output or export at the very end?
- Doxin 6mo ago
  yes, exactly.
- Karliss 6mo ago
  It isn't even necessary to create triangle meshes during export. You can export as step files. It is a commonly used brep based file format supported by almost any "proper" CAD software. Triangle mesh based modelers can't easily export good step files because they don't operate at that level of abstraction.
- rowanG077 6mo ago
  In professional CAD systems, geometry is not stored as triangle meshes but as mathematically defined surfaces (such as parametric and NURBS surfaces). Triangle meshes are only generated as approximations for rendering. This is analogous to vector graphics (SVG/EPS) versus raster images (PNG/JPG). Any serious manufacturing will work require a STEP (or something equivalent) which stores these parametric surfaces rather than a mesh.

ur-whale 6mo ago

> I'm not sure I understand your comment Try to do the following with OpenSCAD: 1. put a sphere and a torus somewhat close to each other 2. find the shortest segment between the two surfaces 3. place an infinite cylinder whose axis is aligned with the segment you just found 4. fillet the cylinder with both the torus and the sphere along its intersection curve with each surface This is very, very hard to do with OpenSCAD.