Geometry nodes: sampling Z position from curve to mesh

Question

I have a mesh that I want to bend along the curve, then move all vertices to match its Z position. Here's the process:

Mesh in X length of the curve
Bend the mesh to curve on XY plane
Align mesh's Z positions to the curve, using the X position from step 1 for curve length sampling. And there's a problem - the mesh is not properly aligned with curve, depending on the angle it's too low or too high. I assume I have to correct the X length input for sampling, but I have no idea how to do this.

Edit: the blend with the case: https://blend-exchange.com/b/Pav9wL2L

However, the mesh you show here can be easily constructed with Geometry Nodes. Or is it actually a more complex mesh? — quellenform, Jun 29 '22 at 14:22
It's complex mesh - I want to bend any input mesh possible, so I can't generate it from curve — UserNoRandomNumber, Jun 29 '22 at 14:23
Does this answer your question? how to bend geometry with geometry nodes — quellenform, Jun 29 '22 at 14:35
I'm using that method for the step 2, but for step 3 I need to only bend Z positions, while this method would rotate the whole mesh. — UserNoRandomNumber, Jun 29 '22 at 14:39
I don't understand the part about "bend Z positions". Can you explain this a bit more? — quellenform, Jun 29 '22 at 16:27
That means I add Z position to the target mesh from the curve to align the curve on Z position, only Z position, without rotating the mesh — UserNoRandomNumber, Jun 29 '22 at 16:40
@quellenform it's a 'Z Up' deformation I think.. One route: capture curve Z, flatten curve, deform mesh to flat curve, offset by captured Z. You or me? — Robin Betts, Jun 29 '22 at 16:47
@RobinBetts Yes, that could be so. But could also be different ...I still don't understand it exactly :D — quellenform, Jun 29 '22 at 16:49
@quellenform Here's the blend file https://blend-exchange.com/b/Pav9wL2L — UserNoRandomNumber, Jun 29 '22 at 17:26
@UserNoRandomNumber OK, here's another version. Hope it's getting there. See Edit. — Robin Betts, Jun 29 '22 at 21:06

Robin Betts · Accepted Answer · 2022-06-29T21:05:23.040

1

I hope this is what you're after.. it's just an adaptation of the X Curve Deform group from here, which you say you are using, changing the mapping in the curve's coordinates.

X to the position on the curve
Y to the cross-product of the curve tangent with (0,0,1), flat to XY, at right-angles to the tangent
Z to (0,0,1)

The new arrangement is shown below:

The result:

It would be simpler to adjust the tilt to make the curve 'Z Up'.. figuring that one out, unless @quellenform gets there first :)

You could take this futher in the mesh, by, for example, flattening the tops of the turrets to XY

edited Jun 29 '22 at 21:05

answered Jun 29 '22 at 18:10

Robin Betts

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Well, @RobinBetts, you have taken the cake once again ;-) – quellenform Jun 29 '22 at 18:24
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@quellenform Unless I can figure it, I'll post the 'Z-up' Q as one of my own.. just an invitation to have think about it :D – Robin Betts Jun 29 '22 at 19:00
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It works well on the spiral, but on other curves it's getting misaligned image – UserNoRandomNumber Jun 29 '22 at 19:05
@UserNoRandomNumber See Edit – Robin Betts Jun 29 '22 at 21:13

Geometry nodes: sampling Z position from curve to mesh

1 Answers1