Sketcher: Bezier curves

[NormandC]

I can also live with visible circles if it means having BSplines in the Sketcher as opposed to no BSpline at all.

Really, a button to toggle the visibility of the circles (if it's doable) would quite easily assuage my cleanliness issues.

I'll try to get some time aside to test this!

Weight control in Sketcher BSplines can easily become a big feature point for FreeCAD.

Agreed, since as I wrote I think at least the mid-range commercial CAD software I know about don't have this.

[triplus]

My first impression was things could easily get over-complex. But seeing how easy it has become to grasp the concept behind poles/weights in sketcher i feel it would be a shame if we wouldn't go after more. That is if @abdullah is preprepared to implement more of everything. As usually when you are confronted with some task you need to do you usually end up in a position where you need it all.

[abdullah]

Not something to become obsessed with! I very much like how you went straight into the most comprehensive BSpline support. Weight control in Sketcher BSplines can easily become a big feature point for FreeCAD.

Once upon a time, there was a Russian guy who gave the Sketcher solver a most generic tangency support by adding a not very widely known "Angle via point" constraint (yeah that strange thing that you can constraint an angle with a selection of three elements almost nobody knows about). Half angle, half tangency, half perpendicular (yes 3 halves, you can normalize later), apart from driving crazy other developers at first, this constrain forces every developer wanting to support a new type to write a function to return the normal at a point of the curve, and in return provides seamless tangency support among any supported curve. This is indeed FreeCAD's Sketcher core of complex tangencies/perpendicularities (e.g. arc of parabola to whatever).

Today, thanks to this, and for non-periodic BSplines with proper endpoint multiplicity, without almost writing any code, we get endpoint tangency of whatever to BSpline without any De Boor recursion or else:

bspline-endpoint-tangency.png (13.98 KiB) Viewed 1328 times

For this, which I am sure will be very useful in the introduction of simple but powerful BSpline support and for your long term service to FreeCAD's Sketcher, I am honored to give you DeepSOIC, the highest award of FreeCAD's Sketcher, the BSpline-tangent-to-parabolic-arc-tangent-to-ellipse-arc-tangent-to-hyperbola-arc award (so that if you wish, you constrain its 18 DoF to shape it as you wish). Thanks for this gem.

sketcher-tangency-prize-DeepSOIC.png (19.72 KiB) Viewed 1328 times

[microelly2]

My first impression was things could easily get over-complex. But seeing how easy it has become to grasp the concept behind poles/weights in sketcher i feel it would be a shame if we wouldn't go after more. That is if @abdullah is preprepared to implement more of everything. As usually when you are confronted with some task you need to do you usually end up in a position where you need it all.

I see a wide field of possibilities
I have done a demo for hyperboloids for a german forum thread
and I see the great power to design when the ribs(yellow area) and the backbone(pink area) are filled by sketcher bsplines.

https://youtu.be/P9m6O2fHbqs

[NormandC]

a most generic tangency support by adding a not very widely known "Angle via point" constraint (yeah that strange thing that you can constraint an angle with a selection of three elements almost nobody knows about).

Wait. What?

I'll be damned. Never knew this was possible (I see it was added to the wiki, I hadn't noticed )

I am honored to give you DeepSOIC, the highest award of FreeCAD's Sketcher, the BSpline-tangent-to-parabolic-arc-tangent-to-ellipse-arc-tangent-to-hyperbola-arc award

Might be a tiny bit long to write on the bronze plaque

To get an idea whats behind weights and knots
https://youtu.be/H-_XNOpCQb4

Thanks for the video!

[DeepSOIC]

, I am honored to give you DeepSOIC, the highest award of FreeCAD's Sketcher, the BSpline-tangent-to-parabolic-arc-tangent-to-ellipse-arc-tangent-to-hyperbola-arc award (so that if you wish, you constrain its 18 DoF to shape it as you wish).

What a nice birthday present I just got

That reminds me about the need to upgrade this system to support arbitrary point on BSpline, not just endpoints. That's going to be a big adventure.

[microelly2]

I am honored to give you DeepSOIC, the highest award of FreeCAD's Sketcher, the BSpline-tangent-to-parabolic-arc-tangent-to-ellipse-arc-tangent-to-hyperbola-arc award

Might be a tiny bit long to write on the bronze plaque

We should design a ring with this long word using the "Macro Circular Text" extension "Macro Helix Text" and then transform it as a Nurbs to fit the finger mesh of DeepSOIC.

[abdullah]

I see a wide field of possibilities
I have done a demo for hyperboloids for a german forum thread
and I see the great power to design when the ribs(yellow area) and the backbone(pink area) are filled by sketcher bsplines.

https://youtu.be/P9m6O2fHbqs

You do cool things! Very nice video.

Wait. What?

I'll be damned. Never knew this was possible (I see it was added to the wiki, I hadn't noticed )

Well, if I had to bet, I would have said you were one of those who knew about it... after this my expectations of who actually knows about this are coming down a lot

Might be a tiny bit long to write on the bronze plaque

We may put BStPAtEAtHA (actually it is odd that it can more or less be pronounced)...

[triplus]

What a nice birthday present I just got

Happy birthday.

[abdullah]

What a nice birthday present I just got

Happy birthday!

That reminds me about the need to upgrade this system to support arbitrary point on BSpline, not just endpoints. That's going to be a big adventure.

Is notthat what you already did (with the help of a point, which is point on object on the curve)?. The problem is that I can not write the CalculateNormal for the whole curve without undue burden and I do not need it for STAGE 1 anyway.

We should design a ring with this long word using the "Macro Circular Text" extension "Macro Helix Text" and then transform it as a Nurbs to fit the finger mesh of DeepSOIC.

ehhh, that sounds like a much better idea than the short form...