[AnIrishDuck]

An analogy is the difference between vector and bitmap graphics.

CAD programs aren't just a different set of operations on the same data, they use an entirely different representation (b-rep [1] vs Blender's points, vertices, and polygons).

These representations are much more powerful but also much more complex to work with. You typically need a geometric kernel [2] to perform useful operations and even get renderable solids out of them.

So sure, I suppose you could build all of that into Blender. But it's the equivalent of building an entire new complex program into an existing one. It also raises major interoperation issues. These two representations do not easily convert back and forth.

So at that point, you basically have two very different programs in a trenchcoat. So far the ecosystem has evolved towards instead building two different tools that are masters of their respective domains. Perhaps because of the very different complexities inherent in each, perhaps because it makes the handover / conversion from one domain to the other explicit.

1. https://en.m.wikipedia.org/wiki/Boundary_representation

2. https://en.m.wikipedia.org/wiki/Geometric_modeling_kernel

[diggan]

> CAD programs aren't just a different set of operations on the same data, they use an entirely different representation (b-rep [1] vs Blender's points, vertices, and polygons).

So with that in mind, there should be something that is possible to build in CAD, but impossible then to build in Blender?

I know the differences between the two, I understand they're fundamentally different, yet I seem to be able to produce similar results to others using CAD, so I'm curious what results I wouldn't be able to reproduce in Blender.

Any concrete examples I could try out?

[AnIrishDuck]

Sure. Create a diamond polygon and revolve it around a point.

Blender has methods and tools to _approximate_ doing this. It has a revolve tool... where the key parameter is the number of steps.

This is not a revolution, it's an approximation of a revolution with a bunch of planar parts.

BREP as I understand it allows you to describe the surfaces of this operation precisely and operate further on them (e.g. add a fillet to the top edge).

Ditto for things like circular holes in objects. With blender, you're fundamentally operating on a bunch of triangles. Fundamental and important solid operations must be approximated within that model.

BREP has a much richer set of primatives. This dramatically increases complexity but allows it to precisely model a much larger universe of solids.

(You can kinda rebuild functionality that geometric kernels have with geometry nodes now in blender. This is a lot of work and is not a great user interface compared to CAD programs)