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Thread: Best way to create surface between cuve shapes

  1. #1

    Best way to create surface between cuve shapes

    Hi Everyone,

    I wasn't doing any LW modelling for quite a few years, but have a chance now and stumbled upon a problem.

    I am trying to find the best solution to create a shape between two splines. On one end it's a circle, on the other end some other spline shape. It also needs to have a side profile similar to the curve in the attached picture.

    How do you do that in 2019/20? Should I just loft the shape and later try to taper its top part or is there some new(old), clever spline modelling technique that I should be looking into?
    Quick Googling of the problem did not give me any solution, but perhaps I wasn't using proper keywords.

    All ideas for a solution will be appreciated, thank you!

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  2. #2
    Curmudgeon in Training Ma3rk's Avatar
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    I'd have to play around with it but there are a number of spline tools native to work with. LWCad might, but again I'd just have to play.

    I recently got familiar with Spline Bridge which isn't what the name implies as it actually works with poly ends. It gives you some spline adjustments in the process is all.

    If you start with spline curves & make them N-Gons, do the Spline Bridge on them then Sub patch, the shape of where the polys were now conform to the original curve. I'll handle dissimilar point count, but you'll get various issues.

    I'd think a rail extrude process might work too but don't hold me to that.
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  3. #3
    RETROGRADER prometheus's Avatar
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    https://www.lightwave3d.com/assets/p...entry/cm_loft/


    you can also use arrayed polygon shapes and run cm_loft and have it loft, not only curves.
    lsc script..should work in 64 bit as well.

    Edit, checked on LW modeler 2019.1.1 64 bit.
    Works.

    Noticed, you have a profile curve, that I donīt think cm loft handles, it just loft between surfaces opposite to each other.

  4. #4
    Electron wrangler jwiede's Avatar
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    Quote Originally Posted by kamiru View Post
    Hi Everyone,

    I wasn't doing any LW modelling for quite a few years, but have a chance now and stumbled upon a problem.

    I am trying to find the best solution to create a shape between two splines. On one end it's a circle, on the other end some other spline shape. It also needs to have a side profile similar to the curve in the attached picture.

    How do you do that in 2019/20? Should I just loft the shape and later try to taper its top part or is there some new(old), clever spline modelling technique that I should be looking into?
    Quick Googling of the problem did not give me any solution, but perhaps I wasn't using proper keywords.

    All ideas for a solution will be appreciated, thank you!

    Click image for larger version. 

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ID:	146866
    Click image for larger version. 

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    Perhaps Ken Nign's Spline Lathe? https://www.lightwave3d.com/assets/p.../spline-lathe/

    It's lscript so there's a decent chance it still works, and seems to be the operation you're attempting.
    Last edited by jwiede; 02-12-2020 at 03:45 PM.
    John W.
    LW2015.3UB/2019.1.4 on MacPro(12C/24T/10.13.6),64GB RAM, NV 980ti

  5. #5
    Electron wrangler jwiede's Avatar
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    (deleted - dbl post)
    John W.
    LW2015.3UB/2019.1.4 on MacPro(12C/24T/10.13.6),64GB RAM, NV 980ti

  6. #6
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by jwiede View Post
    Perhaps Ken Nign's Spline Lathe?

    It's lscript so there's a decent chance it still works, and seems to be the operation you're attempting.

    Thanks for the heads up ..have downloaded it and will test.
    Otherwise, simple spline patching perhaps, you do have to make the curves open though, I think.
    here the manual patch per selected spline curves selected counterclockwise, the profile curve was made by selecting the starting point of the lower curve (tiny diamond representation) and the starting point of the top curve and then go to make open curve, now that only gives a straight curve, so you want to add points to that curve in order to tweak it as a curved profile curve.

    now it works as well to run the full autopatch, so you do not need to select the curves at all in fact...and will patch it all at once, so that may be better depending on, just wanted to showcase this so the splines are a bit more visible here.

    I started with simple discs and selected itīs points and made open curves, I think for full complete circle, you would need to tweak the points when starting the disc, perhaps adding a point very near the starting point..but I havenīt really done a full close circle curve and patched it..so not entirely bullet proof for now.

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  7. #7
    RETROGRADER prometheus's Avatar
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    Correction...you do not need open curves, you can do it with close curved, ergo removing the issue of a not fully closed shape.

    after setting up the two initial main curves you need more than one provile curve..but I am not able to close the patch properly...was so long time ago I did things with spline patching.

  8. #8
    RETROGRADER prometheus's Avatar
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    Yep...itīs working, after running the first manual patch, you need to flip it all,then select the final curves for closing.

    Since the polys are created single sided, and depending on which order they are selected for patching, and since you need to flip the whole patch in order to complete finish the circle shaped path, there will be a missmatch in polyside facing, so you need to go to detail/polygons and make them doublesided.



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  9. #9
    RETROGRADER prometheus's Avatar
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    And to make the process easier, you could install artspheres free aw divide to set segments on the profile curve if you start with a simple joining of points as mentioned..which gives you a straight curve.
    in order for aw divide to work ..you need to have the selected curve in edge mode then run aw divide.

    Note, not tested on 64 bit, not tested on anything else than lw 2015, and the Version I got, may be a special version which artsphere made...not sure.

    if not dividing the curves that way, you either manually have to do it, or draw a spline correctly with startin point and snapping properly.

    And final stage..make sure to merge all points in order to secure it to be subpatch proof.

    And correction, do not make it double sided as I mentioned before.. better to use unify normals, or you will have issues with the subpatch after merging points.

  10. #10
    TrueArt Support
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    Quote Originally Posted by kamiru View Post
    How do you do that in 2019/20? Should I just loft the shape and later try to taper its top part or is there some new(old), clever spline modelling technique that I should be looking into?
    Check EasySpline http://easyspline.trueart.eu

  11. #11
    Hi!

    Thank you. I already made some test yesterday, using Ma3rk's recommended SplineBridge tool, and after a little bit of tweaking, I could use it for the job.
    And now in the morning I just read about "Spline Lathe", so something more to play with, later this evening. Prometheus' tests looks promising. Thank you all one more time!

  12. #12
    Electron wrangler jwiede's Avatar
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    Quote Originally Posted by prometheus View Post
    And to make the process easier, you could install artspheres free aw divide to set segments on the profile curve if you start with a simple joining of points as mentioned..which gives you a straight curve.
    in order for aw divide to work ..you need to have the selected curve in edge mode then run aw divide.
    @Prometheus: Part of the reason I suggested SplineLathe was because it allows a convenient way to alter number of curve segments on-the-fly while building the form, while maintaining radial symmetry etc.

    @kamiru: Presuming 4-way/90deg radial symmetry using SplineLathe should be fairly direct to lathe up the form in question.

    Trying to do it using native patches (or better, EasySpline) and manually ensuring proper radial symmetry is maintained is doable as well, but would take a bit more planning (and effort): If shape is 4-way radially symmetric, do a 90deg swathe with mirror symmetry on, capture and rotate that 180deg segment another 90deg further, then re-mirror to get full 360deg. If shape is only 2-way radially symmetric, do 180deg segment using patches with mirror symmetry on to yield full 360deg.

    Hope that makes sense, ask questions if unclear what I meant. If the form has radial symmetries present, that's typically going to be easier to replicate with a lathe operation over a loft operation.
    Last edited by jwiede; 02-12-2020 at 08:05 PM.
    John W.
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  13. #13
    RETROGRADER prometheus's Avatar
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    Quote Originally Posted by jwiede View Post
    @Prometheus: Part of the reason I suggested SplineLathe was because it allows a convenient way to alter number of curve segments on-the-fly while building the form, while maintaining radial symmetry etc.

    @kamiru: Presuming 4-way/90deg radial symmetry using SplineLathe should be fairly direct to lathe up the form in question.

    Trying to do it using native patches (or better, EasySpline) and manually ensuring proper radial symmetry is maintained is doable as well, but would take a bit more planning (and effort): If shape is 4-way radially symmetric, do a 90deg swathe with mirror symmetry on, capture and rotate that 180deg segment another 90deg further, then re-mirror to get full 360deg. If shape is only 2-way radially symmetric, do 180deg segment using patches with mirror symmetry on to yield full 360deg.

    Hope that makes sense, ask questions if unclear what I meant. If the form has radial symmetries present, that's typically going to be easier to replicate with a lathe operation over a loft operation.
    Yes, if the form can do with radial symmetry, the spline lath seems nice and best to use, but spline patching allows to change the profile differently for many cross section profile curves.
    Yes, spline patching takes a bit of consideration and planning to ensure all curves is aligned properly and how to select them to patch properly, you really need to constantly work with splines to get it flowing more naturally when the workflow becomes programmed in to your brain, havenīt used it for years I think.

    Easy spline sure, always been a bit curious about it,would be interesting to know if he would develop it even further.
    Otherwise the lwcad nurbs and smart meshing seems the most interesting, even though it is expensive, not going to invest in any of it until I see some significant core changes in modeling for lightwave though(obviously layout)

    Also recently got notified about the curves to mesh addon for blender that I need to research first.

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