Not so much as get in the way, but I was a bit sad to find out that that there’s not much I can do with extrusions in grasshopper. Like having a deconstruct extrusion component that could give you the top face, bottom face and the extrusion vector. Heck, even the extrude components in grasshopper return a closed brep instead of an extrusion when you pass a surface and a vector (I get its probably for maintaining stability across versions).
Also, extrusions cannot be made when you use surfaces with holes in them right? This kind of defeated the purpose of extrusions for me. I basically wanted to make something akin to lego blocks where my top and bottom surface will always be the same. However, there would be possibilities that these surfaces could have holes and therefore I was unable to use extrusions.
I like the idea of extrusions, if they could have holes in them and be possible to be made in grasshopper, I would love to use them. It would make a lot of my scripts much simpler than they are right now.
Hi -
I moved your post from the thread on light-weight extrusion objects in Rhino as this is different enough in Grasshopper…
The extrusion object type was introduced in Grasshopper 1 in Rhino 8. In the first several Service Releases, extruding geometry would result in extrusion objects. This caused lots of issues with Grasshopper definitions that were created in Rhino 7, and the behavior was reversed.
Note, however, that when you pipe the Brep output from an extrusion component through the Extrusion parameter, the output is an extrusion object.
I had absolutely no idea. I had tried to make a hole in a box in rhino and found it being converted into a brep which made me think that it does not support holes.
In general there is a lot of weirdness in how Rhino handles extrusions. For instance, if I extrude a planar surface in rhino, it gives me a brep (which I guess makes sense as the same happens in grasshopper)
But then exactly when are extrusions made??? Is the box and cylinder command the only time an extrusion is created? It is strange if the only way to convert a brep into an extrusion is by using grasshopper as you mentioned above. We don’t get to play around with extrusions much if we dont even have access to them most of the time. Extrude Surface, Gumball Extrude and Push-Pull should give you extrusions.
Next, I need to know what exactly an extrusion is. Is it defined purely by a planar surface and a vector? If so, can we get a deconstruct extrusion component that returns the same? This will make it massively useful. Right now the only reason to use it seems to be that it reduces file sizes when you know your objects are just simple extrusions.
What I meant to say is that a box with a hole is still an extrusion. In rhino if you make a box, and cut a hole into it, it becomes a brep even if there is no need to as is evident by this.
The ‘UseExtrusions’ setting also says that its only for planar extrusions -
@wim is it possible to have a setting that keeps extrusions as extrusions (or perhaps even converts breps into extrusions when they meet the criteria). I can very easily do this in grasshopper by just doing this. This actually ensures that I get the intended benefit of the extrusion class.
It’s still a “Closed Brep” though.
