help me bend of a flat shape following a certain radius

Replies to This Discussion

Permalink Reply by David Rutten on April 22, 2014 at 10:20am

How do you want to define the bending properties?

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David Rutten

david@mcneel.com

Permalink Reply by Andrei Raducanu on April 22, 2014 at 2:38pm

preferably as an angle and a radius for the "fillet".

i guess i could make the end shape out of 3 surfaces - the planar ones and the curved one (where it bends), and define the lateral edges of the curved one by making it's flat(developed) equivalent in order to get the uv coordinates of the points that define the edges

Permalink Reply by David Rutten on April 23, 2014 at 12:30pm

I'm trying to make a bending space morph. It seems to finally work for my own testcase, but there could well be bugs in it still.

The input is some geometry and one arc that defines the bending. I attached the the Transform.gha which has the component. Please test the living daylights out of it.

It's probably much slower than the Rhino bend command. And it would also be a good idea to explode curves ahead of time and only morph those that are in the bending region. The ones 'before' and 'after' the arc can just be transformed linearly. 

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David Rutten

david@mcneel.com

Attachments:

• bend test.gh, 5 KB
• Transform.zip, 74 KB

Permalink Reply by Andrei Raducanu on April 23, 2014 at 4:11pm

well isn't the timing just dandy... Thanks a lot! i'll give it a go tomorrow, see where it gets me

Permalink Reply by David Rutten on April 24, 2014 at 2:58am

Well, the timing is not particularly surprising. You asked for it, I made it...

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David Rutten

david@mcneel.com

Permalink Reply by Andrei Raducanu on April 24, 2014 at 2:39pm

First of all, thanks a lot (i'm actually flattered by this)! Second of all, i'm so excited it works!

I wanted to see if the bent surface has the same dimensions as the original so in order to do this i tried to unroll it and i discovered the Rhino Unroll component works only if the angle between the arc and the surface orientation is a maximum of about 5.2deg (0.09rad), as in the attached pic. For higher angles it says that the surface has double curvature.

I also attached the rhino file containing the "double curvature" surface.

I am now trying out other arcs and whatnot to see how it works and where there are particularities. I be back.

PS: didn't know you could write this kind of stuff in expressions: x-5*UnitZ Smoove!

Attachments:

• teste.3dm, 86 KB

Permalink Reply by Andrei Raducanu on April 24, 2014 at 3:13pm

here's another thing i discovered: the direction of the arc is important (meaning if the curve is flipped or not). it needs to flow with the surface, otherwise it gives weird results (doesn't bend the surface, but rotates it, as in the attached example)

Attachments:

• bendtest.gh, 15 KB

Permalink Reply by David Rutten on April 24, 2014 at 3:13pm

...i discovered the Rhino Unroll component works only if the angle between the arc and the surface orientation is a maximum of about 5.2deg (0.09rad)...

Could be due to tiny amounts of double-curvedness. The morphing should be a completely area and length preserving, developable operation. However geometry is resampled during a morphing operation which may introduce ripples if a principle deformation direction is not (anti)parallel to control-points directions.

PS: didn't know you could write this kind of stuff in expressions: x-5*UnitZ Smoove!

Cool huh?

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David Rutten

david@mcneel.com

Permalink Reply by Andrei Raducanu on April 24, 2014 at 3:33pm

something i find a bit off is that the Arc component doesn't let me introduce negative angle values, in order to make the arc form the other way around. I guess i should flip its base plane, but there is no flip plane component from what i see (there are workarounds, off course, but you taught us to be lazy bastards...)

Permalink Reply by David Rutten on April 25, 2014 at 2:09am

Yeah the Arc needs fixin'

I'll make sure that angle domains are handled properly in the next release.

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David Rutten

david@mcneel.com

Permalink Reply by David Rutten on April 25, 2014 at 3:17am

It's a bit weird. The only way I can seem to fix this properly means the resulting arc may have a different plane rotation and angle domain than specified. It will look correct, but not be exactly what you asked for, as what you ask for may result in an invalid Rhino arc.

Is that ok? Doesn't sound ok does it?

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David Rutten

david@mcneel.com

Permalink Reply by David Rutten on April 25, 2014 at 3:30am

At any rate, you now always get a valid arc, even though the arc properties are changed if I had to fix it after the fact. This is technically a breaking change that could invalidate existing GH files, however I think the new behaviour is so much better than the old and the likelihood that it breaks something is so small that I'm willing to put it out there for the next release.

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David Rutten

david@mcneel.com

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