Comment by ur-whale | Hacker News Reader

Comment by ur-whale | Hacker News Reader

There is (among many other) one thing that I truly like about Blender: with its gigantic add-on ecosystem it is on the path to becoming the standard platform for everything 3D.

Or rather: the one place where everything you can do with 3D can come together under the same roof: CAD, CAM, Architecture, Interior Design, 3D reconstruction, Scientific Visualization, Animation, 2.5D drawing, Artistic Modeling, Prototyping, Industrial Design, Simulation, Rendering, Special Effects (of course), etc ... I'm certainly forgetting 80% of the list.

Take any of the other 3D packages out there in all the domains I listed: none of them has anywhere near the breadth and versatility of Blender, and pretty much none of them are capable of importing 3D work from other packages the way Blender can.

I hope various industries involved in 3D will finally recognize this fact and the economic value it brings about. The SFX industry has already recognized it. Fingers crossed, the other will follow.

How does CAD modelling work in Blender? I thought solid geometry manipulation like in CAD software was fundamentally different to what Blender does (surfaces only)?

There's https://www.cadsketcher.com/ addon for Blender. Blender isn't really a CAD program, but apparently it's got enough 3D functionality that it's possible to do CAD in it. Would need to hear from someone more familiar with CAD than I to know whether it's really viable yet or not. Blender's excellent for everything I've personally needed to do in 3D thus far though. (Mostly models / animations for use in game engines.)

Blender doesn't support STEP file import or export, so it is not a viable CAD program. The add-on is probably great for creating dimensioned parts for use in animations and other things Blender does. But there is no interoperability with manufacturing or simulation tools.

It is a stretch to call Blender a CAD. What I think distinguishes parametric CADs is that in Blender you edit the body while in CAD you edit a set of operations that produce the body. This sequence is then processed by geometric modelling kernel to produce the end result. Editing and rendering is the easier part of it.

Sketcher mentioned is probably letting you create dimension accurate objects by hand, but it is far from being a proper CAD.

A 5s check of the documentation (so I may be way off), looks like Sketcher co-opts blender's UI to make it a front end to a CAD app (SolveSpace). So it does get you operations modeled to geometry like a real CAD app.

Thanks for all the responses. As I said, I'm not a "CAD guy", so I didn't really know for sure, but now at least (thanks to y'all folks) I have a somewhat better understanding where "the line" between Blender 3D (and similar programs like Maya, Lightwave 3D, etc) and CAD actually lies. ;)

In my experience, it isn't really very good at it. I've moved to OpenSCAD for cad work, and am very happy with its design philosophy (if not its user experience)

CAD modeling in Blender is only possible with geometry nodes.

I did some projects using geometry nodes. It is a nice step towards CAD modeling because it is fully parametric.

CAD models are mathematical models and thus infinit accurate. Solid models are not. But sometimes they are good enough. I create a lot of models in Blender for 3D printing.

In the BlenderBIM Add-on, CAD modeling works by providing a dedicated modeling interface that interacts with the IFC data model. IFC is an ISO standard that describes geometry, data, objects, processes, and relationships, for the built environment (i.e. BIM). IFC's geometry is based on STEP, so modeling in IFC has similarities to modeling in STEP. You can have swept solid extrusions, revolutions, true arcs and circles, but also some things that don't exist in STEP but are specific to the built environment, like the parameters for an I-shaped beam.

So like other Blender add-ons that do this already (e.g. CAD Sketcher) the BlenderBIM Add-on bypasses Blender for most geometric operations. You define using the dedicated modeling interface, the IFC data model is updated, then the triangles are visualised by Blender, but the under-the-hood CAD definition is there.

The geometry processing layer is done by IfcOpenShell, which is a layer on top of OpenCASCADE (but in the future, may make more use of CGAL or its own custom geometry processing code).

That said modeling buildings are typically simpler than manufacturing CAD modeling. Buildings have forgiving construction tolerances, and are often assemblages of off-the-shelf products where it is not necessary to redefine the exact product shapes. (i.e. place a packer here, place a sprinkler there, whether the sprinkler looks like a sprinkler or is geometrically just a cube in my model makes little difference to construction or maintenance operations).

Is there a good way to work with bulid123d (or cadquery) parametric CAD with Python and Blender as a CAD? All three are built with OCC OpenCASCADE.

IFC: Industry Foundation Classes: https://en.wikipedia.org/wiki/Industry_Foundation_Classes

BIM: Building Information Modeling: https://en.wikipedia.org/wiki/Building_information_modeling

I'm not currently aware of any integration, but since it is based on OpenCASCADE, there may be certain shapes that "just work" with IFC. This is similar to how FreeCAD uses IfcOpenShell to directly serialise some FreeCAD shapes into IFC geometry.

Rendering the triangle meshes and polygon meshes is actually a ’nice to have’ tip of the iceberg in CAD/CAM/BIM flows and Blender doesn’t really help in the domain problem as such.

In general design workflows feed data to downstream consumers. Two top ’consume’ pipelines are around drawings and CNC machine control (STEP).

Rendering everything nicely is something that is nice to have but does not help in the design process, and for project coordination you probably want an online shared project view (e.g. Trimble Connect and many others).

As a private consumer it’s ofc nice to have a free too to use to tap into industrial data flows but it does not really help you in integrating into them (at least yet, but I might be wrong - data is just data).

I never claimed that Blender was at the level of more focused CAD/CAM and other specialized tool.

I also never claimed that rendering was the only thing you'd ever want to do downstream of building a CAD model. There is a ton of things other than rendering you might want to do with a 3D model initially produced in a cutting-edge CAD package, none of which are possible in the package itself.

On the other hand, if you've ever tried to import - say - an animation or a blob-based model in something like Fusion 360 or Catia ... the whole thing is simply laughable.

Whereas Blender can gobble up pretty much anything that looks like 3D data and give you a huge list of tools to manipulate, edit, display, and change it. No other tools, proprietary or OSS can get anywhere near it in terms of generality.

The fact that Blender, and everything it can do even for a straight CAD-to-manufacturing pipeline is not on your radar doesn't mean it doesn't exist or make it less interesting.

I still think that it would have been better if BIM had not been created in opposition to STEP.

> ... "on the path to becoming the standard platform for everything 3D."

For a great many purposes it's already there, and for what little that Blender isn't capable of in that space, there's always things like the Godot Engine, which happens to be a rather Blender-friendly game engine. If I remember correctly, there's a couple few other open source game engines that also go out of their way to support Blender as a part of the workflow, but Godot is the one I'm currently learning / somewhat familiar with.

Reply on news.ycombinator.com