Curves workbench

[Chris_G]

Lets track the issue on the curves workbench repo then?

Yes please.

[ChrisWomble]

Having managed to make the gordon surface tool work for my trivial example (thanks for all the models, everyone who posted). I been trying to apply the same technique to the surface I would really like to model:

Screenshot from 2021-08-25 22-20-50.png (17.06 KiB) Viewed 1902 times

But the tool does not give me the result I would like:

Screenshot from 2021-08-25 22-20-50.png (17.06 KiB) Viewed 1902 times

Can anyone suggest what it is I'm doing wrong?

[Chris_G]

Putting 2 profiles so close to each other produces heavy oscillation.
See how the curve changes here :

oscillation.gif (171.61 KiB) Viewed 1876 times

Try to model your surface with curves that are more evenly distributed.

[ChrisWomble]

Thanks Chris - that is an excellent and intuitive explanation!

What I am hoping to achieve is a surface which transitions from the top profile to the bottom profile, but which quickly loses the sharp corner of the top profile. Can you suggest an approach which would allow me to do that?

[hammax]

... besides being a fan of Gordon - but sometimes a simple 4-section loft works better.
(knowing from ships hulls design...)
There are redraws caused by FC-Version conflict - very soon I'll get a 64-PC!!

Simple_Loft_2.PNG (45.05 KiB) Viewed 1848 times

[Pauvres_honteux]

Trim and split are just very common tools...

They sure are!
Amending to that I'd say, having them as separate tools opens up for showing two different icons in the tree. That way one can directly and visually see which tool/operation was used and therefor emediately know what that particular tool produced (two separate surfaces or one joined surface).

Further the split tool can be incorporated in a "surface-to-surface-radii-tool" (it's yet to be created) in such a way it automatically splt them surfaces the user selects and apply a radius (or radii) of choice along the intersection. This creates a much more Topo-naming stable solution for radius/radii.

Background fact: a trim command produces a common edge which becomes the radius/radii parent. And here lies the problem, the topo-naming chain will eventually become so long it breaks.

Perhaps we should make a feature request for trim and split, so they don't fall between chairs?

In the end all trim commands project a curve

Huh, there you go! Out of curiosity, how did you find out about that?

... find the intersection curve ...

Regarding intersections in general, there's a feature request for it: issue #3301

[ChrisWomble]

... besides being a fan of Gordon - but sometimes a simple 4-section loft works better.
(knowing from ships hulls design...)
There are redraws caused by FC-Version conflict - very soon I'll get a 64-PC!!


Simple_Loft_2.PNG

Thank you hammax - this is exactly what I wanted to achieve. I will spend some time unpicking what you have done to understand it better. Such a quick response - I'm really very grateful.

[Cekuhnen]

Huh, there you go! Out of curiosity, how did you find out about that?

In Alias I have the curve created before split and the curve remains.
.
Good proposal for the intersection container.
You can do intersection points via a datum plane and datum points and then later put a sketch on that datum plane and project the points into the sketch. https://forum.freecadweb.org/viewtopic. ... 5&start=10
This is working but kinda more steps than needed - would be ideal just be inside the sketcher.
.
.

I read in the past that other surface modelers hide the curve.

Having managed to make the gordon surface tool work for my trivial example

I am puzzled how you managed to place the MidSketch onto the Sketch/Profile Back and Profile Front.

Did you find an intersection point or is that why in Sketch the paths are broken into two parts ?
.

Screen Shot 2021-08-26 at 8.18.40 AM.png (51.63 KiB) Viewed 1783 times

[ChrisWomble]

I am puzzled how you managed to place the MidSketch onto the Sketch/Profile Back and Profile Front.
Did you find an intersection point or is that why in Sketch the paths are broken into two parts ?

In the sketch, I extended the bezier with line segments. The top point of the bezier and the line segments each have a horizontal constraint - specifically so I could place the datum plane to provide the additional profile at the height I wanted it.

[Cekuhnen]

I am puzzled how you managed to place the MidSketch onto the Sketch/Profile Back and Profile Front.
Did you find an intersection point or is that why in Sketch the paths are broken into two parts ?

In the sketch, I extended the bezier with line segments. The top point of the bezier and the line segments each have a horizontal constraint - specifically so I could place the datum plane to provide the additional profile at the height I wanted it.

Ok good that is what I assumed.
Good example for a find intersecting point command in the sketcher