[Soc-2014-dev] Weekly Report #10: NURBS Modernization

Sat Jul 26 17:58:30 CEST 2014

Would it be possible to also include step as a format? OpenNURBS is not
used by many cad systems.
On Jul 26, 2014 10:16 AM, "claas kuhnen" <info at ckbrd.de> wrote:

> I see,
>
> The mesh MOI produces has actual holes in it and it adds NGONS where
> possible.
> Maybe my understanding is wrong here but wouldn't this be sufficient and
> possible
> already with Blender?
>
> The MOI mesh imports work great besides normal shading problems in Blender.
>
> Claas
>
> - - -
>
> *Claas Kuhnen*
>
>
> *(715) 513-9118 *
> *www.ckbrd.de*
> *info at ckbrd.de*
>
>
> On Sat, Jul 26, 2014 at 9:41 AM, Dalai Felinto <dfelinto at gmail.com> wrote:
>
>> > I use MOI as my main nurbs to mesh converter and it uses ngons a lot
>> not for holes but surfaces.
>>
>> I think ngons is a generic term, not necessarily always referring to
>> the same data structure. (SketchUp ngons handles holes very nicely
>> too).
>>
>> What I mean is, the ngons implementation in Blender doesn't support
>> holes. Blender's ngons is a Radial Edge implementation, so although it
>> could support holes, it was never fully implemented.
>>
>> Cheers,
>> Dalai
>> --
>> blendernetwork.org/dalai-felinto
>> www.dalaifelinto.com
>>
>>
>> 2014-07-26 10:31 GMT-03:00 David Fenner <d4vidfenner at gmail.com>:
>> > Moi is the best nurbs to poly converter i have ever found. Fast, robust,
>> > flexible, clean... Definitely somewhere to aim to.
>> >
>> > El jul 26, 2014 9:27 a.m., "claas kuhnen" <info at ckbrd.de> escribió:
>> >
>> >> I use MOI as my main nurbs to mesh converter and it uses ngons a lot
>> not
>> >> for holes but surfaces.
>> >>
>> >> Claas
>> >>
>> >> On Jul 26, 2014 8:51 AM, "Dalai Felinto" <dfelinto at gmail.com> wrote:
>> >>>
>> >>> Hi,
>> >>>
>> >>> > * Does anyone know of good example code for making a BMesh out of
>> >>> > n-gons? N-gons would make the meshes produced by Alt+C *much*
>> cleaner.
>> >>>
>> >>> Be aware that N-gons don't support holes (at the moment), so you may
>> >>> get buggy meshes during this conversion. But as Sergey said, you don't
>> >>> need to convert the nurbs to ngons.
>> >>>
>> >>> Cheers,
>> >>> Dalai
>> >>> --
>> >>> blendernetwork.org/dalai-felinto
>> >>> www.dalaifelinto.com
>> >>>
>> >>>
>> >>> 2014-07-26 8:39 GMT-03:00 Sergey Sharybin <sergey.vfx at gmail.com>:
>> >>> > Hi,
>> >>> >
>> >>> > It's cool to hear you're doing progress, but what about committing
>> the
>> >>> > stuff
>> >>> > to Git? Last commit was done on Monday and in the report you claim
>> >>> > having
>> >>> > progress since that. Commit the stuff even if it's not production
>> >>> > ready.
>> >>> > I've asked about this several times already.
>> >>> >
>> >>> > Before you go to importing or making improvements to curve->mesh
>> >>> > conversion
>> >>> > i'll demand wrapping existing code up, making so it's used in blende
>> >>> > (and
>> >>> > commit everything!)r and preparing demo files for this.
>> >>> >
>> >>> > As for ngon examples, you just need to fill in mpoly and mloop
>> arrays
>> >>> > actually. MOD_boolean_util.c has examples (it operates with
>> >>> > DerivedMesh, but
>> >>> > it's almost the same as you need for curve->mesh conversion).
>> >>> >
>> >>> > Also, what are the plans for the next week?
>> >>> >
>> >>> >
>> >>> > On Sat, Jul 26, 2014 at 1:43 PM, Jonathan deWerd <
>> jjoonathan at gmail.com>
>> >>> > wrote:
>> >>> >>
>> >>> >> This week was largely eaten up by a task that I thought would be a
>> >>> >> quick
>> >>> >> copy/paste job but turned into a morass of debugging math code.
>> >>> >> Fortunately
>> >>> >> that part is done -- and the result is much prettier smooth curves:
>> >>> >>
>> >>> >> http://wiki.blender.org/index.php/User:Jjoonathan/New_NURBS_Eval
>> >>> >>
>> >>> >> Progress This Week:
>> >>> >> * Finished the new evaluation code. Key features:
>> >>> >> * Computes any number of partial derivatives analytically
>> >>> >> * Immediate application 1: compute normals analytically = it looks
>> >>> >> smooth
>> >>> >> again :)
>> >>> >> * No nasty lighting artifacts near trim edges
>> >>> >> * No seams where curves touch/loop due to calculating normals at
>> >>> >> polygon
>> >>> >> corners
>> >>> >> * Immediate application 2: handle (literal) edge cases of eval
>> points
>> >>> >> lying on knots correctly
>> >>> >> * Immediate application 3: uses 1/2 as many divisions, so possibly
>> >>> >> it's
>> >>> >> faster, although I didn't check
>> >>> >> * Future application: computing error bounds
>> >>> >> * Performed extensive verification of the new eval code
>> >>> >> * Mesh points coincide with Rhino surfaces
>> >>> >> * All 1st, 2nd (partial) derivatives agree with Mathematica's NURBS
>> >>> >> implementation (direction, amplitude correct).
>> >>> >> * Made progress on the trim curve tessellator.
>> >>> >> * NOTE: last week I mistakingly said that I had finished the trim
>> >>> >> curve
>> >>> >> tessellator when I actually meant to say that I had finished the
>> >>> >> surface
>> >>> >> tessellator.
>> >>> >> * Refactored the import code so that it can make detatched curves
>> >>> >> * Adjusted memory management & blenloader
>> >>> >> * The trim curve tessellator isn't a sticking point, I only got
>> around
>> >>> >> to
>> >>> >> working on it again today. The eval code was the sticking point.
>> >>> >>
>> >>> >> Things that were done that don't officially constitute progress:
>> >>> >> * Spent Thursday finishing rotation surface & interpolation surface
>> >>> >> chapters in P&T
>> >>> >>
>> >>> >> Things that must be done before I can import the sample .3dm files:
>> >>> >> * Finish the trim curve tessellator
>> >>> >> * Rotation surfaces
>> >>> >>
>> >>> >> Things I could use help on:
>> >>> >> * Does anyone know of good example code for making a BMesh out of
>> >>> >> n-gons?
>> >>> >> N-gons would make the meshes produced by Alt+C *much* cleaner.
>> >>> >>
>> >>> >>
>> >>> >>
>> >>> >> On Jul 19, 2014, at 1:28 PM, claas kuhnen <info at ckbrd.de> wrote:
>> >>> >>
>> >>> >> So agree I am very excited about this
>> >>> >>
>> >>> >> On Jul 19, 2014 1:27 PM, "Sergey Sharybin" <sergey.vfx at gmail.com>
>> >>> >> wrote:
>> >>> >>>
>> >>> >>> Seems to be rather nice progress. Would be cool if all the bits
>> are
>> >>> >>> committed and some .blend in shared which demonstrates the stuff.
>> >>> >>>
>> >>> >>>
>> >>> >>> On Sat, Jul 19, 2014 at 4:31 PM, Jonathan deWerd
>> >>> >>> <jjoonathan at gmail.com>
>> >>> >>> wrote:
>> >>> >>>>
>> >>> >>>> Progress:
>> >>> >>>> * Finished code to tessellate trim curves!
>> >>> >>>>         see:
>> >>> >>>>
>> http://wiki.blender.org/index.php/User:Jjoonathan/NURBS_In_Blender
>> >>> >>>> * Rewrote knot code to match the conventions in the math
>> literature,
>> >>> >>>> tested for compatibility by comparing meshes
>> >>> >>>> * Worked on adapting a better NURBS evaluation algorithm that can
>> >>> >>>> produce first and second derivatives (for normals and error
>> bounds,
>> >>> >>>> respectively).
>> >>> >>>>         it's still buggy.
>> >>> >>>> * Worked further on the NurbEdge interface to handle imported
>> trim
>> >>> >>>> curves
>> >>> >>>>         still working on code to match endpoints that are
>> separated
>> >>> >>>> in
>> >>> >>>> UV space but coincide in R3 due to either wrapping in UV space
>> >>> >>>> (cyclic
>> >>> >>>> NURBS) or coving
>> >>> >>>>
>> >>> >>>> Todo:
>> >>> >>>> * Finish tracking down the NaN-producing bugs in the new surface
>> >>> >>>> evaluator
>> >>> >>>>         From there, should be easy to implement good normals
>> >>> >>>> * Finish NurbEdge so that it at least handles wrapping in UV
>> space.
>> >>> >>>> This
>> >>> >>>> will allow importing of most .3dm files.
>> >>> >>>> * Implement revolution surfaces.
>> >>> >>>>         Demo Claas's hairdryer model!
>> >>> >>>>
>> >>> >>>> On Jul 12, 2014, at 11:14 AM, Jonathan deWerd <
>> jjoonathan at gmail.com>
>> >>> >>>> wrote:
>> >>> >>>>
>> >>> >>>> > (Apologies if this is a duplicate email. I see a copy of this
>> >>> >>>> > email in
>> >>> >>>> > gmail's "sent" folder but I don't see one in my inbox, so I'm
>> >>> >>>> > sending
>> >>> >>>> > again.)
>> >>> >>>> >
>> >>> >>>> > Progress:
>> >>> >>>> > * Finished the code that traverses BReps from 3dm files and
>> cuts
>> >>> >>>> > them
>> >>> >>>> > into surfaces
>> >>> >>>> > * 2D Trim curves import as Nurb objects that are appended to a
>> >>> >>>> > NurbList in their parent surface
>> >>> >>>> >       Just curves currently, I still have to get multi-part
>> loops
>> >>> >>>> > working
>> >>> >>>> >       Also they don't seem to be preserved by DNA even after
>> >>> >>>> > calling
>> >>> >>>> > makesdna...
>> >>> >>>> > * Moved surf_gridmesh into bf_blenkernel, promoted curve.c to
>> >>> >>>> > curve.cpp (for future OpenNurbs use), fixed a few small bugs
>> that
>> >>> >>>> > caused,
>> >>> >>>> > moved the GLUT debug code into blender/tests, convinced CMake
>> to
>> >>> >>>> > build and
>> >>> >>>> > link it
>> >>> >>>> > * Wrote, debugged the method that builds the displist from the
>> >>> >>>> > gridmesh
>> >>> >>>> > * Timed it, see pretty graph a few emails back
>> >>> >>>> > * Started writing NurbEdge structure to handle in general the
>> >>> >>>> > sewing
>> >>> >>>> > of trim edges and cyclic edges (e.g. so that spheres don't have
>> >>> >>>> > seams)
>> >>> >>>> >
>> >>> >>>> > Next up:
>> >>> >>>> > * I still need to finish the code that tessellates the trim
>> >>> >>>> > curves. I
>> >>> >>>> > didn't get much time to work on it today, so I'm planning to
>> work
>> >>> >>>> > on it
>> >>> >>>> > tomorrow as well.
>> >>> >>>> > * Get trim curves to load/save from .blend files by figuring
>> out
>> >>> >>>> > what
>> >>> >>>> > I'm doing wrong with makesdna
>> >>> >>>> > * Finish NurbEdge interface for defining edges to sew, get it
>> in
>> >>> >>>> > DNA
>> >>> >>>> > as well
>> >>> >>>> > * Use NurbEdge to implement revolution surfaces
>> >>> >>>> >
>> >>> >>>>
>> >>> >>>> _______________________________________________
>> >>> >>>> Soc-2014-dev mailing list
>> >>> >>>> Soc-2014-dev at blender.org
>> >>> >>>> http://lists.blender.org/mailman/listinfo/soc-2014-dev
>> >>> >>>
>> >>> >>>
>> >>> >>>
>> >>> >>>
>> >>> >>> --
>> >>> >>> With best regards, Sergey Sharybin
>> >>> >>>
>> >>> >>> _______________________________________________
>> >>> >>> Soc-2014-dev mailing list
>> >>> >>> Soc-2014-dev at blender.org
>> >>> >>> http://lists.blender.org/mailman/listinfo/soc-2014-dev
>> >>> >>>
>> >>> >> _______________________________________________
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>> >>> >>
>> >>> >>
>> >>> >>
>> >>> >> _______________________________________________
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>> >>> >>
>> >>> >
>> >>> >
>> >>> >
>> >>> > --
>> >>> > With best regards, Sergey Sharybin
>> >>> >
>> >>> > _______________________________________________
>> >>> > Soc-2014-dev mailing list
>> >>> > Soc-2014-dev at blender.org
>> >>> > http://lists.blender.org/mailman/listinfo/soc-2014-dev
>> >>> >
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>> >>
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>> >
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