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Curvature handles on spline points

Henk_de_VlaamHenk_de_Vlaam Member, Developers Posts: 239 ✭✭✭
edited June 2019 in Community Support

There is the Curvature constraint since OS 1.98 (20190618 - https://forum.onshape.com/discussion/11865/improvements-to-onshape-june-18th-2019/p1). I hoped to get a wish fulfilled, namely: curvature handles on other than end points of a spline. What I like to do is changing the tangency of any point of existing splines.

I tried to add the new curvature constraint to a third spline point between the end points. As expected that did not work. Then I splitted the spline on that point and added the curvature constraint over there. That did not work either.

So the question is now: how to add curvature handles to any spline point of an existing spline to tweak that spline?
Henk de Vlaam (NL)

Best Answers

Answers

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    owen_sparksowen_sparks Member, Developers Posts: 2,660 PRO
    I don't believe you can, you'd need to join a bunch of individual new entities together.
    Owen S.
    Business Systems and Configuration Controller
    HWM-Water Ltd
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    NeilCookeNeilCooke Moderator, Onshape Employees Posts: 5,528
    The way to do it is to create two splines end to end rather than trying to split an existing one.


    Senior Director, Technical Services, EMEAI
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    tim_hess427tim_hess427 Member Posts: 648 ✭✭✭✭
    @NeilCooke - Is there a reason for not having control handles on non-end points? I've wanted to use this functionality in the past as well, and this seems like a tedious work-around. So, I'm curious if there's some technical reason for this or if this "work-around" is actually the better approach for some other reason I"m not considering. 
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    Henk_de_VlaamHenk_de_Vlaam Member, Developers Posts: 239 ✭✭✭
    edited June 2019

    @NeilCooke,

    The problem is that I have existing splines which are defined by the points of a line plan of a boat. https://cad.onshape.com/documents/65f43343a31e4fdbdd4b0a16/w/7abae95f0e3b34d1da4650cb/e/1d9fe5a32a43bc2bda5e6de7

    Your solution assumes that during sketching you know where the splines have to be curvature constrained, but as you can see that does not work for me because the imperfections only appear as the whole ship hull is ready. To get a proper hull I need the curvature handles only at some specific spline points. 

    Also because of the (earlier) absence of them I paused the modelling of the boat design. By using the new curvature constraint with your work-around I can continue now but I need to replace the improper spline by two or more separate splines and see how that works out, which is awkward. Always having curvature handles at spline points (e.g. FS360) or afterward adding (and removing) them at specific points would be much more comfortable, flexible and efficient.


    Henk de Vlaam (NL)
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    Henk_de_VlaamHenk_de_Vlaam Member, Developers Posts: 239 ✭✭✭
    edited June 2019
    @paul_chastell - Thank you very much for your very extensive explanation. I've learned a lot of that.
    As long as the internal handles are not provided I can use or the coupled two point splines idea of @NeilCooke or (for existing splines) your control system with extra entities .

    But of course I'm looking forward the moment the internal handles will become available.

    @NeilCooke - When creating an IR for that I found an existing one:
    https://forum.onshape.com/discussion/9096/handles-on-all-spline-points
    Henk de Vlaam (NL)
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    paul_chastellpaul_chastell Onshape Employees Posts: 124
    yeah, add your vote to that @Henk_de_V, that's the right one.

    Paul Chastell
    TVP, Onshape R&D
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    SledDriverSledDriver Member Posts: 116 ✭✭✭
    edited June 2019
    I've tried at length to do curved stuff in OS, and it's not really built for it at this point. OS is superb at rectilinear stuff, but as soon as you enter the world of curves, you end up with problems, limitations, workarounds and the like, which can be a cute challenge for your talents, but leaves a lot to be desired. Even if you manage to define your shapes within spec to your requirements, your problems are only just starting if you need to later edit the shape of a curved item.

    I'm not sure why, but the OS team doesn't seem very focused on improving the curve abilities of the product - the real world is mostly curves. Many curved items in this world simply are not parametrically defined, and any attempt to do so imposes severe limitations on the further development of the product after the initial definition. Same thing applies to meshed surfaces.

    The new match curvature constraint is a big move forward in developing and manipulating spline shapes, but it needs to go further, and thanks to Paul above for the suggested techniques which do help. But it needs to go further and be streamlined.

    I have tried at length to draw smooth flowing boat hulls on OS, but have given up for now. I really hope they get this stuff implemented in a useful way in the foreseeable future, because OS deserves to be successful. IMO It is such a well thought out product, apart from this area. I have total respect for the brains behind the product. I expect in the fullness of time they will provide something which will yet again leave us all smiling as to the elegance, simplicity and ability of the solution.
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    Henk_de_VlaamHenk_de_Vlaam Member, Developers Posts: 239 ✭✭✭
    edited June 2019
    [...] I have tried at length to draw smooth flowing boat hulls on OS, but have given up for now. [...]
    @Henk_de_V said:
    [...] Also because of the (earlier) absence of them I paused the modelling of the boat design. [...]

    @SledDriver

    Remarkable such a common experience.  :neutral:  
    Henk de Vlaam (NL)
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    gda_ctogda_cto Member Posts: 13 PRO
    It's been two years and this is still missing? Seriously annoying. It seems the OS development team have chosen the apple approach of, no you're doing it wrong, as opposed to admitting they're missing functionality. Really disappointing. 
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    Evan_ReeseEvan_Reese Member Posts: 2,073 PRO
    gda_cto said:
    It's been two years and this is still missing? Seriously annoying. It seems the OS development team have chosen the apple approach of, no you're doing it wrong, as opposed to admitting they're missing functionality. Really disappointing. 
    I mean, of course there's additional functionality I want, but for what it's worth, I think they're doing a great job of setting priorities and only launching things they have taken the time to implement thoughtfully.
    Evan Reese / Principal and Industrial Designer with Ovyl
    Website: ovyl.io
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