# Help needed with a spiral stair riddle

Hi, I need to have those spiraling steps aligned on the column surface. Can someone point me to a solution? Thanks in advance!
I already tried the Srinkwrap Constraint but it doesn’t apply to the array objects and I also need to have the array live for adjustments.
I also tried the Curve modifier with a conformed curve after Array but the curve normals are incontrolable.

You can try shrinkwrap only the inner face of the steps to the wall.
And maybe shrinkwrap the outer face to a invisible outer wall.

Thanks but this is the result, also keeping just the inner face and putting a Solidify on top results in irregular shapes of the stairs.

Did you use object offset with the array? Looks like your steps are not rotated.
steps.blend (657.5 KB)

I experimented with it, increase the resolution of the inner and outer tube if the stairs are moving to jaggy if you rotate the array via the empty. Make sure to apply transformations to the walls and the starting position of the stair should between both walls, otherwise you got disformed stairs.

Thanks for assistance but what I have is not a straight cylinder in the middle, but a variable radius. I did try your method with an external wall and a second vertex group but the steps get irregular no matter what type of projection I choose.

There is a solution with instancing then, but i cannot fix the distance problem. Somewhere i have make a mistake i cant find.

steps2.blend (1.0 MB)

I can align the faces on surface with Projection mode in Shrinkwrap but they get irregular on local Z and tilded by surface. I’m thinking that maybe the solution is with drivers or a constraint combination.

Can’t you just create your spiral stair case up the column normally and then apply the modifier so they are individual stairs and then move them locally using normals position away from the pillar? Sorry I just learned how to properly do this. I tried with the curve modifier but need to understand how objects contort around it…not really familiar with that.

It’s even working with part selection, transform to Normal and snap to face.
Still I hope to find a nondestructive workflow for this.

This could work if the data transfer modifier would working, its not. Don’t know why.
steps3.blend (1.0 MB)

Such things would be super easy if there would a modifier to save and restore geometry data. For example save all vertices z-coordinates, shrinkwrap, and then restore vertices z-coordinats, maybe with influence option/add/sub/diff/…
Wouldnt that a good suggestion for the developers?

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I think this is the limit with this method. I collapsed everything, deleted upper rail and extruded verticaly. It almost works but in the second pic you can see where it fails. Face instancing seems like a good enough feature for general cases but it’s not reliable.

Yeah or a better array> curve that makes the difference between geometry and origin with controls for orientation influence and axis locking. There are already good proposals on RightClick but the development is what it is.

“arrange on curve” was ported to 2.80+ yesterday by @cwolf3d maybe is helps with this task.

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Thanks, it works. All that was needed was the constraint for X,Y rotation before the addon to get only horizontal steps and a bit of tweaking the angles in the addon dialogue. It’s now the same workflow I use in 3ds max

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I am glad it works. There is always an Addon in Blender.LOL

That and helpful blendering fellows. Thank you all for assistance!

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