[HN Gopher] Plasticity: CAD for Artists
___________________________________________________________________
Plasticity: CAD for Artists
Author : dgellow
Score : 51 points
Date : 2024-03-08 11:03 UTC (11 hours ago)
(HTM) web link (www.plasticity.xyz)
(TXT) w3m dump (www.plasticity.xyz)
| skybrian wrote:
| I'm wondering whether this is useful for 3D printing and whether
| you _can_ add important measurements when it matters (to make
| parts that fit.)
| CharlesW wrote:
| From a 2022 discussion:
| https://news.ycombinator.com/item?id=30695360
|
| > _Are there parametric features? eg. Can I say "this line is
| 35mm long"?_
|
| > _I want to emphasize to everyone that this is for concept
| artists. It's nurbs used to create interesting shapes and
| fillets. While there are some parametric features, they're
| completely de emphasized compared to something like fusion or
| solidworks_
| oktwtf wrote:
| The software has evolved significantly since 2022, I'd even
| say that the dev has been flexible and enabled functionality
| to bridge some more traditional CAD use cases in modern
| versions. For example when you sketch shapes on a workplane
| you are able to define the measurement aspects, diameters,
| offsets, lengths; you can even quickly define relative angles
| when drawing out segmented lines.
|
| However there are no parametric controls for the elements of
| your shapes or drawings. Keeping these constraints out of
| mind certainly helps me get into a flow when modeling, much
| more akin to subd or poly modeling while maintaining the
| benefits of NURBS. But for adapting models quickly for more
| flexible designs isn't /really/ the tool for it. You can take
| it pretty far though!
|
| I personally use Plasticity to model all kinds of things
| including 3d-printed items (vacuum wall mounting, iPhone lens
| mount, storage cases, clips...) All of these items needed to
| be measured accurately and Plastiticy was able to handle that
| without issue.
|
| I've been using 3d software for 20+ years, Max, Maya,
| Blender, XSI, Houdini, Wings3d, Lightwave, Modo, ZBrush,
| Mudbox... "lots" of 3d software. Some get the job done and
| some are even a pleasure to use, Plasticity decidedly in my
| mind does both.
| timothyb89 wrote:
| I've been using it for light CAD work to design stuff for
| (hobbyist) 3d printing. You can use exact measurements just
| fine. The main issue is that it isn't parametric but for my
| needs that isn't a big issue, and the one-time $150 pricetag is
| wildly easier to swallow than a Fusion 360 subscription.
|
| It's a lot like Blender, if Blender was a few degrees more
| usable for CAD. That said, I've yet to try the Blender CAD
| Sketcher addon (https://www.cadsketcher.com/).
| declaredapple wrote:
| Oh I need to try that addon.
|
| I've been meaning to look for a Fusion360 alternative that
| can run on linux and doesn't cost $$$$/yr.
| graypegg wrote:
| There's also FreeCAD, which is getting better! Definitely
| worth trying the RealThunder fork [0] that handles some
| geometry better than the upstream branch, and is kept up to
| date.
|
| It's still weird. That's for sure. But very much usable as
| a fusion360 replacement for simple to intermediate 3D
| printing work.
|
| [0] https://github.com/realthunder/FreeCAD/releases
| treflop wrote:
| As a hobbyist, Fusion 360 is free, no?
|
| I don't pay for my Fusion 360.
| etrautmann wrote:
| You're limited to 10 design files total for a hobby license
| right?
| jdietrich wrote:
| 10 editable files at any one time. You can have an
| unlimited number of files that are set to read-only, and
| you can freely switch files from read-only to editable or
| vice-versa.
| bigboy12 wrote:
| It's a really an amazing piece of software.
| itronitron wrote:
| this link is just an ad
| owenpalmer wrote:
| why do you say that?
| alted wrote:
| Plasticity is interesting because it is maybe the only way to run
| the Parasolid geometry kernel natively on Linux right now.
|
| Parasolid, the library used to perform the geometric operations
| (the most difficult and important part of a CAD program) also
| powers the likes of SolidWorks (the industry standard), NX, and
| Onshape, and is arguably the best in the world. Its licensing
| cost is presumably a large part of the Plasticity price.
| fsloth wrote:
| Meh. Geometry kernels are oversold. Triangulate, CSG and
| triumph. CSG is the non-trivial part - and Manifold
| (https://github.com/elalish/manifold) is excellent at this.
|
| At least for consumer stuff where you anyway eventually just
| want triangles for either rendering or 3d printing.
|
| If your industrial workflow includes CNC machines you _may_
| benefit from actual analytic surface cuts and unions - maybe.
| Buttons840 wrote:
| Why is it difficult (geometric operations)? Do you have any
| suggestions on how to learn more about it?
| skgough wrote:
| There are two aspects of CAD that are very technically
| complex: parametric modelling and constraint solving.
|
| Parametric modelling is similar to 2D vector graphics formats
| in that instead of defining where vertices are placed in a
| coordinate space, it builds the model based on an instruction
| set that includes primitive shapes like circles but can also
| include complex curves defined using splines (NURBS)[0].
|
| Constraint solving is a way of mathematically deriving the
| possible shapes an object can take based on the geometric
| constraints applied to it. For example, a 2D equilateral
| triangle could be defined by setting the length of one edge
| and then constraining all edges to be of equal length. The
| coordinates of the vertices are derived from these
| constraints.
|
| SolveSpace [1] is an open source parametric modeler with a
| constraint-based solver that you can explore if this is
| something you're interested in.
|
| [0] https://en.wikipedia.org/wiki/Non-uniform_rational_B-
| spline [1] https://solvespace.com/index.pl
| moffkalast wrote:
| CAD for artists is just installing a set dimensions plugin for
| Blender. It's super weird that there's still no native
| functionality to just scale a select in edit mode to a specific
| measurable length value.
| mrob wrote:
| Blender uses an entirely different paradigm: vertex modelling.
| The only true geometric primitives in Blender are vertices,
| edges, and faces. When you insert a "sphere", you're actually
| running code to automatically generate vertices that
| approximate a sphere. There is no inherent "sphereness" to the
| resulting object. You have to decide how close an approximation
| you want up front, and if you get it wrong you might have to
| redo a lot of modelling. This is particularly tricky when it
| comes to constructive solid geometry (CSG), e.g. drilling a
| hole in that sphere by subtracting a cylinder from it. You
| might not have enough vertices to satisfactorily approximate
| the resulting object, and have to use various manual techniques
| to subdivide specific polygons in the right places.
|
| CAD supports true curved surfaces. A sphere in CAD is a genuine
| sphere, and you can decide how accurately to render it
| independently of your modeling operations. CSG is a core
| technique in CAD modelling, with no special tricks needed to
| get good results.
|
| To me, the CAD approach is more intuitive, but it's true that
| vertex modelling can be very fast when you don't need high
| precision, so I can see why artists like it.
| moffkalast wrote:
| Sure, but Blender does support CSG with polygons easily. You
| can do all typical CAD operations, modifiers, parametric
| stuff, you just have to pick your accuracy on the fly, not
| later when exporting. You do realize that everything
| eventually gets turned into polygons before production right?
| Well aside from sheet metal design I guess.
|
| I've lost count how many Fusion360 modelers I've seen that
| can't properly turn their models into a mesh and 3D print
| curved surfaces with visible polygon banding lol.
|
| > vertex modelling can be very fast when you don't need high
| precision, so I can see why artists like it
|
| It's not about speed, it's about control. When making assets
| for rendering all kinds of wild tricks are sometimes needed
| that go beyond modelling solid objects, plus adjusting UV
| coordinates for texturing and the like.
| adastra22 wrote:
| I think you vastly underestimate the difficulty of
| performing geometric kernel operations if you think someone
| could just wing it in Blender. These kernels represent the
| combined effort of literally generations of engineers
| solving really difficult edge case scenarios.
|
| Of course for artists, accuracy probably doesn't matter.
| moffkalast wrote:
| Well I regularly do indeed wing it in Blender. It is
| poorly suited for conforming to specific measurements out
| of the box, but with some plugins it's usable enough.
| Definitely wouldn't imagine it being in spec for any
| professional usage but for hobbyist maker stuff getting
| within 100 microns is more than accurate enough. I mean
| hell, I can't really measure much more accurately with my
| callipers anyway.
| gfodor wrote:
| I love this app.
___________________________________________________________________
(page generated 2024-03-08 23:01 UTC)