May I ask if in Rhino 8, closed multisurfaces can be created with push-pull to create internal hollow solids? (Pushing and pulling a single surface can obtain an internal hollow solid) - as shown in the figure.
No, Rhino doesnât have a way to indiciate that two non-intersecting surfaces (or solids) are supposed to represent a hollow inside. To make a hollow, you need to have something connecting them, such as a hole drilled in the part.
Can you tell me more about why you want to represent a hollow object?
there is similar topics
found this one - but there was another oneâŚ
ok found one moreâŚ
one more
Yeah, the question has come up for as long as Rhino has existed. But Iâm curios if @CTQCTQ has a use case that we havenât heard of before (not that it will make it any easier to implement).
@brian Yes, in Rhino 8, I first created a sphere and then used the PushPull command to offset a certain distance, creating a hollow solid. However, this situation seems to only apply to a single surface and is not useful for multiple surfaces (such as the cube of a shell in the figure).
Ah, ok, then this is more a curiosity than âI need to make hollow objectsâ. Itâs true Rhino just doesnât have a way to represent that kind of object.
@Tom_P Yes, the BooleanDifference command does not work on non intersecting entities.
@brian Although Rhino does not support internal hollow solids of closed multisurfaces, they can be created through Rhinoinside import. As shown in the figure.
Yes you can make such objects in Rhino using NonManifoldMerge but the situations where such a feature is actually useful and not an error are extremely limited. What you are doing here is a pointless academic exercise. THERE IS SO SUCH THING IN CAD AS A âSOLID.â Itâs all surfaces. There is nothing actually âinsideâ a solid. They are ALL hollow. The whole concept of âsolidâ modeling is an abstraction at the layer of the interface.
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One use case is placing magnets or weights inside 3D printed objects. A void must be created to contain the magnet or weight.
Thatâs a massive market Iâm sure, the entire CAD industry is missing out. Oh wait, the slicer can handle it. Still seems unlikely youâre going to actually printâŚa magnet inside the object, youâre gonna assemble it after, the model will contain no voids.
Well, it is possible I suppose to pause the printer halfway and insert the magnet - assuming that it sits at or below the level of the head at the slice level, otherwise there is a collision risk - and then continue the print cycle⌠But thatâs complicated and requires printer supervision by a human.
It does if youâre pausing the printer to insert the magnet into a cavity and the printer then resumes to close the cavity. The model has a hollow area / void in it. Have done this on more than one occasion to ensure a small magnet has no chance of getting out.
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Assembled then plugged is not as clean.
Magnets inside an object: lids and closures
Weights inside an object: vases
Market size: will leave to others, e.g. you
it is quite commonly needed in rendering, for proper refraction
the workaround there is to extract render meshes and join them
No itâs not needed for refraction, objects only need to have their normals pointing the right way to create âinsideâ and âoutside.â
maybe for some simplistic renderers you have used
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