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In geometry nodes, Im trying to add random procedural bend to an array of bezier curves but the node fails whenever a random value is attached. I attached random values in similar places and it works, but it fails here for some reason. Is there any way to get around this without faking it like adding partial bend and random scaling to randomize? enter image description here

, I want the amount of bend to be randomized, not the direction of bend. Basically, I want the y value of the middle handlebar to be random enter image description here

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    $\begingroup$ The problem in your setup is that you connect a field to a static value, but you should be able to connect it to e.g. Set Position > Offset? $\endgroup$ Jan 5, 2022 at 0:31
  • $\begingroup$ I think his interest, and now mine, is how to change the specific control points defining the shape of the curve, not the whole curve at once. It should be possible, but it is extraordinarily obscure here. $\endgroup$ Jan 23, 2022 at 15:40

3 Answers 3

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Yes! :) In Blender 3.0. and Blender 3.1. you can control curves shapes, even if curves are instances. I made all examples below in Blender 3.0.

Solution_1.

Here I create curve with three control points. And I randomly change position of the central point by "Set position" node. In this case "Curve parameter" node and "Float curve" node and "Multiply" math node removes random values from endpoints of the curve, by multiplying this values to zero.

screenshot of node group and result

Solution_2.

Here I create curve with only two control points. And I randomly change position of the points handles. In this case I select target points with "Endpoint selection" nodes.

screenshot of node group and result

Solution_3.

It is a copy of solution_1. But in this case I select central point of the curve with "Endpoint Selection" node and "Not" Boolean math node.

screenshot of node group and result

Solution_4.

It is a hybrid of solution_3 and solution_2. Here I drop to zero handles at the ends of the curves, and enhance my control of curves shapes by adding control of central points handles.

screenshot of node group and result

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  • $\begingroup$ I forgot your nickname, but I recognized you by node layouts. :) What do you mean by Blender 3.+ ? Will it work in 3.0? From my tests the Solution 1. doesn't, but maybe I done screwed up: i.imgur.com/gMt001Q.png $\endgroup$ Jan 25, 2022 at 12:57
  • $\begingroup$ Missed a sign in a maximum of the random value :) it works for Blender 3.0 (and it was Solution #2, not 1) $\endgroup$ Jan 25, 2022 at 14:08
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    $\begingroup$ @MarkusvonBroady I made booth solutions in blender 3.0. I can proof this. :) It is easy to recognise Blender 3.0 by "Curve/Spline Parameter" node design. If you see this: docs.blender.org/manual/en/latest/_images/… - this is 3.0. But if you see this: docs.blender.org/manual/en/3.1/_images/… - this is 3.1. $\endgroup$
    – 3Dhedgehog
    Jan 25, 2022 at 14:27
  • $\begingroup$ Interesting... I only installed 3.1 just now to see if it works there (it didn't, but then I noticed it was a bad range on Random Value in my setup - I thought I have it going from minus to plus, but it was only minus. Surprising that it works, I was considering building a single curve, for each 3 points treat 1st and 2nd as a separate curve, instance it as many times as the number of curves, and remove all but 2 points for each realized instance to separate the curves... Needless to say your setup is better. :) $\endgroup$ Jan 25, 2022 at 14:31
  • $\begingroup$ @MarkusvonBroady wow! Thank you so much for bounty! I am new here. So i don't know is it already mine or i should do something more to take it, should I? For exampe I can add several other solutions to my answer. :) $\endgroup$
    – 3Dhedgehog
    Jan 25, 2022 at 14:56
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I admit that Erindale has all the tricks here. Went through a pretty long tutorial on building trees which I was thankful for.

![enter image description here

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  • $\begingroup$ If less variation is required, then of course some parameters like resample could be reduced. $\endgroup$ Jan 28, 2022 at 2:06
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    $\begingroup$ I also upvoted your answer :) Well done solution for creating very chaotic and organical shapes. Just one remarc: probably "equal" node do nothing here, because modulo already output "...001001001..." and all "1" values will be boolean "yes", and all "0" values will be boolean ''no". So if you Cntrl+X "equal" node it will work the same way. $\endgroup$
    – 3Dhedgehog
    Jan 28, 2022 at 4:45
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you can randomize it like this:

enter image description here

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  • $\begingroup$ I should've specified, I want the amount of bend to be randomized, not the direction of bend. Basically, I want the y value of the middle handlebar to be random $\endgroup$
    – Relevred
    Jan 5, 2022 at 0:23

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