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This is a little cylinder I want to fit into the exact centre of joint of icosahedra. How to make proper constrains?

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  1. Distance from cylinder to each bend must be equal
  2. Central axis of cylinder should be normal to circumscribed sphere.

untitled.blend

geodesic dome online

kyb
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2 Answers2

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You can get there in three steps:

  1. Select inner faces of the joint
  2. Co Mesh > Snap > Cursor to selected (3D cursor is the center for new objects)
  3. Add a cylinder with six sides - it will be precisely in the middle

enter image description here

jachym michal
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  • Thank you for response, make case is slightly harder. Bends are not in the same flatness. They form a sphere dome. With you instruction i can make only one part of what i want. – kyb Jun 03 '20 at 16:08
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Maybe taking a step back.. if so, apologies..

  1. Enable the shipped Add-on 'Add Mesh: Geodesic Domes', create desired dome.
  2. On a copy of the dome, X > Delete Only Faces (The instancer can be set not to render, anyway)
  3. In its Instancing panel, set to Verts, and Align to Vertex Normal
  4. Parent your cylinder to the dome. The cylinder's mesh will need to be aligned along its local Y axis in Edit Mode.

enter image description here

  1. On the other copy, ShiftCtrlB bevel the vertices
  2. Again, delete faces.. select one of the new short edges and Shift G Select Similar > Length
  3. Delete those, and Object > Convert the remainder to a curve.
  4. Set the curve's U resolution to 1, and use its native Bevel, also at the lowest resolution, to give a square profile to the spars.

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  1. Convert back to a mesh if desired, and combine the copies.

enter image description here

... something along these lines? Tweak, take the bits which serve your purposes?

Robin Betts
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  • Phew dodged a bullet almost posting same (well dupliverts part) but so much lesser (you are a master illustrator) answer here https://blender.stackexchange.com/questions/181117/set-items-axis-to-pass-through-world-origin#comment303018_181117 Worth mentioning the instances are aligned local Y axis to vert normal? – batFINGER Jun 03 '20 at 20:20
  • @batFINGER :) Done. This is counter-intuitive, at least, to me. I really would have expected it to be Z? There's usually a consistent grammar to these things in Blender.. I must just not have twigged, yet. – Robin Betts Jun 03 '20 at 21:05