3

I'm trying to make a spiral slide with geometry nodes.

I've been able to do what I want with Instance on Points, but I cannot find a way to extrude from each instance or similar. I've used Align to Euler to achieve the arc pointing downwards.

It seems I should use Curve to Mesh, but then I cannot use the Euler approach.

I've made an example to visually show how far I am so far. I'm on Blender 3.2.1

enter image description here

Duarte Farrajota Ramos
  • 59,425
  • 39
  • 130
  • 187
Magnuzoid
  • 57
  • 4
  • Why not use Curve to Mesh directly on the curve you are instancing over instead, using a semi-circle section? – Duarte Farrajota Ramos Aug 03 '22 at 14:07
  • When using the Curve to Mesh on the Spiral I can't control the rotation, at least not with what I know about geonodes. – Magnuzoid Aug 03 '22 at 14:19
  • You don't need to, Curve to Mesh always orients your profile perpendicularly to the curve without manual intervention – Duarte Farrajota Ramos Aug 03 '22 at 14:21
  • It might be that I don't understand fully.. but when I use Curve to Mesh, it rotates like this: https://media.giphy.com/media/Yu9FkLqNqVoDBbsw7t/giphy.gif – Magnuzoid Aug 03 '22 at 14:26
  • https://imgur.com/a/veLP0yy simplified geo node example for clarification :) – Magnuzoid Aug 03 '22 at 14:32
  • Sounds like the XY Problem, that is probably what you should have been asking about in the first place. See https://blender.stackexchange.com/questions/49265/how-to-edit-curve-but-not-ruined-tilt-settings/ or https://blender.stackexchange.com/questions/71787/object-on-curve-wont-stay-flat/ https://blender.stackexchange.com/questions/35771/why-does-a-bezier-curve-twist-when-rotated – Duarte Farrajota Ramos Aug 03 '22 at 14:36
  • What you need to use here is the set curve tilt node. However, still struggling myself on where to pull the correct tilt from, as this has to be procedurally modified along the spiral curve – aliasguru Aug 03 '22 at 14:48

2 Answers2

7

To align the tilt of the curve upwards, you can use the following node setup:

enter image description here

This calculates an angle from the values for normals, curve tangents and the up vector, which is plugged directly into the node Set Curve Tilt.

quellenform
  • 35,177
  • 10
  • 50
  • 133
  • how did you figure out the formula on how to calculate the tilt? – aliasguru Aug 03 '22 at 15:57
  • Looking forward to trying this! Have left my computer for today but will try tomorrow - and yes, how did you get to this beautiful formula? Usually I can mess around and fond a suitable solution, but this is above my head – Magnuzoid Aug 03 '22 at 16:14
  • nothing but amazing - thanks! – Magnuzoid Aug 04 '22 at 13:49
6

enter image description here

You can get over the tilt problem by constructing the spiral in the flat, capturing the spiral's Parameter or Length, converting to a mesh, and then setting the height as a function of the captured attribute:

enter image description here

Robin Betts
  • 76,260
  • 8
  • 77
  • 190