Curves workbench

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Vincent B
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Re: Curves workbench

Post by Vincent B »

Hi Chris,
Do you think it could be possible to use Sweep2Rail by get the splines instead wireframe?
Gordon could use them.
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Chris_G
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Re: Curves workbench

Post by Chris_G »

You would like Sweep2Rails to generate a curve network that could used by Gordon surface ?
That should be possible, I need to have a look.
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Vincent B
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Re: Curves workbench

Post by Vincent B »

Any idea to correct this curve to close the gordon? :roll:
Maybe a new feature "CorrectedCurve" with a deltaZ at start and end? :D
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Cekuhnen
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Re: Curves workbench

Post by Cekuhnen »

Chris_G wrote: Mon Jun 28, 2021 5:30 pm You would like Sweep2Rails to generate a curve network that could used by Gordon surface ?
That should be possible, I need to have a look.
Chris

Is there a way to make that GORDON like surface also use G1 G2 for the edges?

The surface WB GORDON does not and compared to the BREP surface tool which has G1 the GORDON produces much cleaner geometry.

FreeCAD has a blend surface with G1 G2 which is nice
A Square or loft tool that does the same would be super useful.
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Chris_G
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Re: Curves workbench

Post by Chris_G »

GlouGlou wrote: Wed Jul 21, 2021 7:58 pm Any idea to correct this curve to close the gordon? :roll:
Maybe a new feature "CorrectedCurve" with a deltaZ at start and end? :D
Your middle rail is not touching the profile.
Is it the Workbench's job to fix bad input ?
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Chris_G
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Re: Curves workbench

Post by Chris_G »

Cekuhnen wrote: Wed Jul 21, 2021 9:48 pm Is there a way to make that GORDON like surface also use G1 G2 for the edges?
That would be great, ... but far from simple.
Cekuhnen wrote: Wed Jul 21, 2021 9:48 pm The surface WB GORDON does not and compared to the BREP surface tool which has G1 the GORDON produces much cleaner geometry.
It would be easier to understand you if you used the correct naming.
Gordon Surface is part of the Curves workbench.
I suppose what you call the "BREP surface tool" is the Filling tool of the Surface WB
Cekuhnen wrote: Wed Jul 21, 2021 9:48 pmthe GORDON produces much cleaner geometry.
Surface_Filling is a very general purpose tool, that can fill a boudary wire made of ANY number of edges.
But any face is supported by a geometry surface that always has 4 sides.
So Surface_Filling computes a (4-sided) underlying surface that passes through, and extends beyond the boundary wire, and trims it.
filling.png
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On the other hand, Gordon surface has a much stricter input requirement : a grid-like network of curves. So it can produce a geometry surface that fits the curve network, without any trimming needed : the final face is the whole computed surface.
Here is the Gordon surface result on the same set of boundary edges :
gordon.png
gordon.png (55.11 KiB) Viewed 2024 times
Cekuhnen wrote: Wed Jul 21, 2021 9:48 pm FreeCAD has a blend surface with G1 G2 which is nice
A Square or loft tool that does the same would be super useful.
Probably. The problem is that I am reaching several personal limits :
- Geometry and math ability
- Coding skill
- Free time
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Cekuhnen
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Re: Curves workbench

Post by Cekuhnen »

This are very fair points - thanks for being clear about them.

Edit:

I am curious why the sweep2rails is actually using first a fill and then you make a point cloud and via generating the curves bend the first surface into shape.

is this what an sweep 2 rail command internally would do automatically anyway?
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Vincent B
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Re: Curves workbench

Post by Vincent B »

Chris_G wrote: Thu Jul 22, 2021 7:48 am
GlouGlou wrote: Wed Jul 21, 2021 7:58 pm Any idea to correct this curve to close the gordon? :roll:
Maybe a new feature "CorrectedCurve" with a deltaZ at start and end? :D
Your middle rail is not touching the profile.
Is it the Workbench's job to fix bad input ?
Why not. :D the input is not very nice but close to perfect.
that's why I would like to correct it. 0 at the beginning and epsilon Z to the end.
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Curves WB : New BlendSolid tool

Post by Chris_G »

Hello,
I have added a new tool to the Curves Workbench.
It is called BlendSolid.
The goal is to join 2 solids by a selected face, with smooth continuity.

blendsolid.png
blendsolid.png (101.72 KiB) Viewed 1897 times
Before activating the tool, you must select the following items :
- a face on each object
- 2 consecutive edges for each wire of each face, in order to choose how to associate edges of the 2 shapes

For example, on the following picture, you would select
- the 2 highlighted faces
- then the red and blue edges of the cylinder
- then the red and blue edges of the cube.
Or :
- the 2 highlighted faces
- then the red edges of each object
- then the blue edges of each object
blendsolid_selection.png
blendsolid_selection.png (20.81 KiB) Viewed 1897 times

One important restriction is that the 2 faces must have the same number of edges.

The main properties are :

- Continuity1 and Continuity2 that set the G.. continuity with input shapes
- Samples sets the number of blendCurves that are generated to compute each surface.
- Auto Scale is the method used to compute the scaling (shape) of each surface. It is recommended to keep it on Regular Poles. (Minimize Curvature often produces bad result.)
- Scale Samples is the number of blendCurves that are computed in Auto Scale mode.
- Shape Type is read-only. It informs about the shape type that could be achieved (Solid, Shell, or Compound). If it is not Solid, it means the the tool failed somehow.
- Untwist Algo should stay on ManualMatch for now. Maybe I'll be able to add an "Auto Untwist" algo in the future ?
- Matching Shapes are the edges selected for untwisting (see Selection above)
- Offset is a list of vectors (one for each wire of the faces). It is not representing 3D points. It is coding the edge indices on each face.
blendsolid_properties.png
blendsolid_properties.png (123.28 KiB) Viewed 1897 times

The resulting BlendSolid is parametric.

GlouGlou wrote: Thu Jul 22, 2021 3:59 pmWant to give a try ?
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Re: Curves workbench

Post by chrisb »

Great stuff! Thanks!
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