[HN Gopher] Constraint-based geometry (CAD) sketcher for Blender
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Constraint-based geometry (CAD) sketcher for Blender
Author : khimaros
Score : 64 points
Date : 2022-05-22 17:17 UTC (5 hours ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| pen2l wrote:
| This a pretty interesting development.
|
| I'm wondering to what degree tessellation is configurable, e.g.
| if I want polygon-dense output to have nice curvatures for
| additive manufacturing, or polygon-light output for rapid
| workflow and speed if I have complicated geometry.
| cultofmetatron wrote:
| I really wish there was a open source cad modeler on the same
| level as blender. It really is next level. My dream for if my
| startup succeeds is to bootstrap such a product. Especially if it
| had a fully extensible architecture. it would be possible for
| third party services to plug into it (both paid and open source)
| for creating and designing new inventions.
| NonNefarious wrote:
| Same. I don't know much about 3-D modeling, but I took a Maya
| class years ago and was annoyed at design flaws in its UI.
|
| I didn't expect much from Blender, owing to the shitty UI
| offered by other widely-used open-source software like GIMP and
| Audacity. But I was pleasantly surprised by Blender, and I'm
| excited to learn it.
|
| But the CAD space is dominated by pay-only rental-style
| solutions, and even most of those seem to be Web-based
| (Autodesk) or Windows-only (SolidWorks).
| dapids wrote:
| Is blender not open-source?
| cultofmetatron wrote:
| 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.
| NonNefarious wrote:
| Yeah, thanks for that explanation of the issue.
| dapids wrote:
| Thanks for the insight.
| throw_m239339 wrote:
| 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).
| Animats wrote:
| 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.
| rurban wrote:
| solvespace is much better than blender in modelling.
| Piezoid wrote:
| This add-on is using solvespace for solving constraints.
| throw_m239339 wrote:
| FreeCAD? It is used professionally by a lot of big companies
| such as Behringer to design hardware.
|
| https://www.freecadweb.org/
| slabity wrote:
| I use FreeCAD relatively often (once or twice a month) over
| the past 3 years and I can say with certainty that it is
| nowhere close to Blender in terms of quality or stability.
|
| I've been keeping up with the latest versions, but even with
| all the bug fixes that go in I am more likely than not to
| have it segfault or lose its GL context or something else
| that causes it to crash. This isn't even hyperbole, I
| literally get 2 or 3 crashes at minimum per session, and when
| it happens it's rarely reproducible. I simply save after
| every couple of changes I make because I've just come to
| expect it to happen.
|
| When it does work, I frequently run into problems like the
| infamous topological-naming-issue that, while I understand it
| is a difficult software problem to fix, I do not run into in
| the other CAD programs I've used. The only way to avoid these
| kinds of issues is to understand the underlying cause and
| then adjust your workflow so that you don't run into them.
|
| The only reason I use it is because there's not really any
| other FOSS that fits the same niches. I did learn about
| SolveSpace and this blender plugin today though, so I'll
| probably take a look.
| samwillis wrote:
| The fundamental problem is that there isn't a good enough open
| source parametric kernel. FreeCAD uses OpenCascade which is the
| best available, but quite dated, FreeCAD is pushing it to its
| limits.
| alhirzel wrote:
| Is there a good description of what such a parametric kernel
| does? Or are there any alternatives to OpenCascade?
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