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I want to recreate this in blender geometry nodes. I suppose it is possible but it is more math than i hoped it is. Can someone help please?

he

enter image description here

Marko Bogunovic
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    yes its more math. it looks similar to the shape i recreated, see my answer in https://blender.stackexchange.com/questions/270409/how-can-i-plot-this-cartesian-equation-in-geometry-nodes – Harry McKenzie Aug 15 '22 at 15:19
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    To me, it looked like the inside of a doughnut. (With which we are only too familiar). On closer inspection of the Houdini nodes.. it is the inside of a doughnut.. :D – Robin Betts Aug 15 '22 at 15:23
  • hey you're right! should be easy to plot using the torus equation blender already has in the xyz math surface templates! and then limit the u and v domain :D – Harry McKenzie Aug 15 '22 at 15:25
  • If your question was solved, please be so kind and mark the answer that contributed to the solution as "Accepted Answer". This will make it easier for others to see which way leads to the solution, and the question will no longer appear as unsolved. Thank you! Here you can find more information: What should I do when someone answers my question?. If you still didn't get a solution to your question, please be kind enough to address it. – quellenform Aug 23 '22 at 21:58

2 Answers2

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You could solve this as follows:

enter image description here

Here I create a mesh with an arc as a profile and a circle.

Then I separate the horizontal edges from the vertical edges.

I split these and convert them back into curves.

With Trim Curve I extend the curves depending on the current frame.

enter image description here


(Blender 3.2)

With the same technique you can determine not only the end of the curves, but of course also the beginning:

enter image description here enter image description here

quellenform
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  • I don't know why i always thought of profile curve needing to be something closed. I didn't realize you could use an arc as the profile curve which is really cool effect! – Harry McKenzie Aug 16 '22 at 01:46
  • This is almost exactly what i need but i need horizontal lines, circles to slowly move upward also, so i have emerging effect in full – Marko Bogunovic Aug 16 '22 at 10:48
  • @MarkoBogunovic I'm afraid I don't quite understand that, they do move slowly upwards, don't they? Can you explain or show this in more detail? – quellenform Aug 16 '22 at 11:00
  • i just updated original post, added your model with manually added rotation on z axis for everything, and moving the slider on your arc node to create this growing/emerging effect. But the thing is, beginning and the end of the arc should stay on same positions and horizontal circles should disappear/emerge when they reach the end. Hope i made it clearer! – Marko Bogunovic Aug 16 '22 at 11:23
  • watch closely latest gif i uploaded – Marko Bogunovic Aug 16 '22 at 13:13
  • @MarkoBogunovic If I understand this correctly, you would otherwise simply have to animate the values for Start Angle and Sweep Angle additionally. – quellenform Aug 16 '22 at 13:45
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'Same difference' :) Always slower than @quellenform .. slightly different approach:

enter image description here

but I think his explanation will suffice ..

enter image description here

Robin Betts
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  • Good answers need to be well thought out, speed is not everything! +1 ...your answer has at least a Houdini-like gradient as background ;-) – quellenform Aug 15 '22 at 16:59
  • I had to wash up, that's my excuse... and I'm gettin' old :) – Robin Betts Aug 15 '22 at 17:01
  • Same as above, almost exactly right, only if horizontal lines would slowly move upward so we have emerging effect in full. I don't know is it visible in my video? – Marko Bogunovic Aug 16 '22 at 10:50
  • @MarkoBogunovic That effect is slightly visible in my version .. a delay in filling the rings, bottom to top. Set by the 'Addend' in the 'Anim Rings' cluster. I'm restricted by .gif size. I think yours also has a fade, that's another question. I think the easiest way to taht is via the compositor, for pure wireframe. – Robin Betts Aug 16 '22 at 11:29
  • I meant actual movement of the rings up the arc. i updated original post with a new gif. see if it clears it out – Marko Bogunovic Aug 16 '22 at 12:47
  • @MarkoBogunovic Ahh, OK, quellenform's method would work better than mine, for that. He/you could just animate the tilt of the main circle, or the start-angle of the arc sent around it. – Robin Betts Aug 16 '22 at 13:41