I'm new to rhino, how do I do this (tensile / mesh model)

[urbansketcher]

Hello everyone, I need to model something resembling this - a central rod with shorter rods placed in horizontal alignment along the central rod plus a tensile fabric stretched over it, no need for complicated material property simulation (at this time). If there are tutorials to take me step by step though the process, commands and workflow, or some other software is faster to learn for this particular task, please let me know, because I’m on the clock here my alternative is just drafting it by hand using fillets.

[hughecchapman]

Others can prob provide better guidance here.

Not sure this is the best approach (esp. if the position/orientation of the poles is crucial) but if you’re happy to freely model the stretch material then position the poles to suit, you could try -

• crudely model the stretch tent fabric as a distorted spheroid

• use the rebuild command to generate an appropriate number of control points

• turn control points on and manipulate control points to distort the surface in a controlled way

• model & position poles

Another approach would be -

• model the poles

• create 3D linework to define key seams of your form, breaking up your form into linework shapes with 4 sides

• use this linework to generate surfaces

• use surface matching to match edges and smooth out your form

[encephalon]

for a really quick preview create a sphere then rebuild or revolve a curve and rebuild to a decent raster (much fine than mine) then select the points where you want to have your protruding parts and use InvertPt followed by the command smooth keep smoothing till you are happy with the result.

for something more accurate with a given structure underneath i honestly would just try that with some other 3d app which has fabric simulation embedded like c4d, blender and whatnot, specifically if you are trying to get these pointy tips. doing this with rhino accurately is not a quick task and without grasshopper probably almost futile, but that all depends what your actual intentions are.

[Tom_P]

simulation

see also here - cloth simulation with grasshopper / kangaroo)

@DanielPiker

shrinkwrap_sharp.gh (24.2 KB)

Here’s a go at this with the current Kangaroo, also using MeshEdit to make the convex hull to start with and Weaverbird.
It’s still not perfect - edges that are part of the input geometry and the convex hull stay crisp, but it can still end up rounding other edges inside as it shrinks.
I’d like to improve this, but I think it will need some slightly different way of finding the collisions, and/or remeshing while shrinking.

shrinkwrap

you might also just play around with some very simple initial geometry.
_line
_pipe
and then use
_shrinkwrap (with 10 to 50 smooth iterations) (left)
or
with some initial offset outwards (middle) and back inwards (right).