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Comment by dapids | Hacker News Reader

Is blender not open-source?

blender is a mesh modeler, That means the underlying represntation of the scene is a a set of surfaces connected by nodes subdivided by triangles. Its efficient and quick for 3d animation and concept art but not so great for cad design.

real cad tools like fusion360, autocad etc are parametric. they represent a shape in the form of constraints. The underlying representation of the shape is different in a way that facilitates modeling something that you are going to create a real world counterpart from.

Yes there are open source cad programs but nothing I've seen comes close to rivaling professional tools the way blender does.

Thanks for the insight.

Yeah, thanks for that explanation of the issue.

Blender is mostly an artistic tool (mesh modelling), which actual CAD software is designed for industrial engineering, accurate physical simulations, manufacturing, and architecture (constraint based modelling).

Yes. Blender has some volumetric operations. You can take the union or intersection of two meshes, or use one to cut out part of another. But it's a bolt-on to an underlying mesh system, and the resulting meshes have lots of ill-chosen triangles.

Serious modern parametric CAD (Autodesk Inventor, Solidworks, etc.) does constructive solid geometry well, but is not well suited to animation. Making a face via CSG is terrible. Although it's gotten better; you can now do sculpted shapes in CAD, because people design cars in them. That has both sides of the hard problem - the smooth shapes must look good, and the bolt holes for the stamping dies must line up precisely.

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