Comment by elcomet
Comment by elcomet 7 hours ago
Can you explain more? Which things are impossible in blender
Comment by elcomet 7 hours ago
Can you explain more? Which things are impossible in blender
Parent's comparison is pretty great, but it shouldn't be "overdone". It's not really the format that's different/a problem (it's not hard to make a blender object from a CAD design - the same way an SVG can be rendered to PNG, and similarly irreversible in both cases), it's the whole design flow.
CAD uses geometry primitives with parameters and exact sizing (e.g. you draw a rectangle of this size, and cut a whole into it this and this offset from one of the corners, and you expand this shape to 3D). As mentioned this can be approximated via geometry nodes, but they are very different in "ideology".
A .step or .stp file encodes the model as mathematical shapes, rather than approximating it with polygons, but it doesn't save the entire parametric workflow or history, only the final result. As far as I know, there is no widely adopted file format that also saves this information.
For architecture, there is Industry Foundation Classes (IFC). IFC is a standard for describing building. FreeCAD supports this natively. There's a tutorial here: https://yorik.uncreated.net/?blog%2F2025%2F002-nativeifc-tut...
Blender has and extension for IFC called Bonsai. https://extensions.blender.org/add-ons/bonsai/
CAD modeller are good at producing parametric 3d models. You can make use of spreadsheets and constraints to create a piece, that will later super easily be changed.
https://en.wikipedia.org/wiki/Constraint_(computer-aided_des...
> CAD modeller are good at producing parametric 3d models
If that's the only thing they do better than Blender, then it sounds like their days are numbered. Has to be more benefits right? Blender exposes a pretty wide Python API, loading spreadsheets ends up pretty simple, and together with Geometry Nodes, you can even visualize it in a way that makes somewhat sense. Constraints been existing for a long time in Blender too.
If you try OpenScad-style adding and subtracting volumes, the syntax is pretty horrific. It is impossible to script objects that way. Quote Gemini:
However, implementing a full OpenSCAD-like syntax and robust CSG system from scratch in Blender Python is complex due to Blender's mesh-based nature versus OpenSCAD's mathematical description. Blender's boolean operations on complex meshes can sometimes lead to topological errors.To be fair though, OpenSCAD works best too if you do this during the generative step and not after the fact. I've used it to remix existing STLs so it definitely does work but you really have to watch the areas where two shapes get close to each other, especially if there is a lot of fine detail.
Did I solve all problems that OpenSCAD might have? Compared to FreeCAD. Me myself think I did: https://youtu.be/eG5lhLYvihQ?si=yA00IYVU4_Zemdxi
Spiritually, Blender is to FreeCAD what Gimp is to Inkscape or what BMP is to SVG. With Blender you're massaging piles of anonymous polygons so they look right aestheticallY, while with CAD you're composing geometric primitives to make a precise blueprint for a 3D object that just happens to be rendered with polygons. The former is better for art while the latter is better for manufacturing.