[Soc-2014-dev] Weekly Report #13: NURBS Modernization

[Sergey Sharybin]

I'm not really sure why you spent time on adding some new functionality
(which is not even documented and in the really questionable way) at the
last coding week instead of making sure someone can actually test your
work. Sample .blend files were requested ages ago, but the whole work is
still remains a mystery (apart from some screenshots in the wiki which are
not so much informative).

Now,
- What is the whole point of the NURBS UV editor? And when this raised in
the project?
- C90 is still not met, you've got loads of cases when you mix code and
declarations. Here's the patch for you http://www.pasteall.org/53523/diff
(and hey, most of the stuff i already sent to you like 2 weeks ago)
- This is tuesday already, and there's still C++11 existing in the code
(c'mon, it takes 3min to zap it), also there's still no final summary page.
- It's too early to prepare patch for the review, the branch is to be
cleaned up.

Things to be done ASAP:
- Make sure your branch compiles for average artist (my bet is that the
proposed patch makes it compilable, but it might be some extra things
required)
- Write the final documentation, making sure artists can follow it and see
the benefits
- Prepare sample .blend files which demonstrates the new functionality
(which keeps being requested since weeks ago!)

And by ASAP i mean really ASAP, evaluation deadline is on friday.


On Sat, Aug 16, 2014 at 1:06 PM, Jonathan deWerd <jjoonathan at gmail.com>
wrote:

> Progress:
> * Added editing functionality to the NURBS UV Editor.
> Knots and trim control vertices can be selected and G-key dragged
> Sundry selection tools (border select, invert selection, select all, etc)
> Add Trim menu, can delete trim with 'x'
> "View All" zooms the UV Editor over the set of active UV patches
> Added entries in the theme table to configure colors in the NURBS UV
> editor (trims get colored based on whether they are AND/SUB/ADD)
> * I got a build set up in Visual Studio for ensuring C89 (and C++90)
> compliance.
>
> This Weekend:
> * Burn away all C99 and C++11 syntax sugar I was using, get things
> building in VS
> * Smash the NURBS branch into a patch for review
> * Write the final summary page
>
>
> This is my last weekly report, but seeing as I still have to assemble the
> final wiki page & such this weekend it won't be my last progress email to
> soc-2014. Therefore I'll hold off on the goodbyes for now :)
>
> Cheers,
> Jon
>
> On Aug 9, 2014, at 4:09 AM, Jonathan deWerd <jjoonathan at gmail.com> wrote:
>
> http://wiki.blender.org/index.php/User:Jjoonathan/NURBS_UVEdit
>
> Progress:
> * Fixed algorithmic bug causing trim to fail if trim curve intersected
> vertex. This was a critical bug that prevented all but specially crafted
> trim curves from being created/imported.
> * Added proper N-gon and per-loop normal support to the convert-to-mesh
> operator (higher quality meshes, supports curves with kinks)
> * Added UV editor for trim curves. Visualization functionality is mostly
> complete; editing functionality is in progress (selections propagate but
> that's it).
> * Fixed bug in .blend read/write code for NurbTrim that prevented undo
> manager from working and merged it back into my main soc-2014-nurbs branch
> * Spent time trying to compile in C90 mode, but I can't seem to do any of
> 1. persuade clang to emit C90 nitpicky errors (variables declared at
> beginning of function etc) 2. build in Xcode with gcc 3. build using UNIX
> makefiles with gcc.
>
> This weekend (i.e. before soft pencils-down):
> * Finish edit functionality in UV Editor (add buttons to call add curve,
> move control points, simplify operators etc)
> * Rotation surfaces
> * Revive Zak's buggy loft/sweep NURBS surface creation code I recently
> unearthed in contrib
>
> Next week (i.e. after soft pencils-down, before hard pencils-down):
> * Get build working on a linux or windows computer (I think I had one
> working in December on Windows using VS) so that I can actually see the C90
> errors
> * Test and bugfix. I suspect there is enough to do on that front to keep
> me busy all week.
>
>
>
>
> On Aug 2, 2014, at 2:34 AM, Jonathan deWerd <jjoonathan at gmail.com> wrote:
>
> Progress:
> * Finished trim curve tessellator [1]
> * Finished code to read/write trim curves from a .blend
> * Added loop-select modifier for NURBS control points (selects a U row or
> V column)
> * Minor UI tweaks (control mesh is thinner and Z-tested, NURBS weight is
> disambiguated from softbody weight, etc)
> * Wrote code to dump internal NURBS state from Blender into GLSL
> visualizer to track down a lingering bug (see below)
>
> This weekend:
> * Track down the trim bug that is causing an explosion of trim polygon
> edges whenever a straight line runs parallel to an edge of a tessellation
> poly
>
> Next week:
> * Rotation surfaces
> * Fix a bunch of style issues and warnings that Sergey brought to my
> attention
> * Prepare a squashed merge
>
> [1] Two weeks ago I accidentally reported finishing trim curve tessellator
> when I meant to report that I had finished the surface tessellator. I later
> clarified the matter, but to resolve all doubt: this week both are
> finished. Well, except for the bug I mentioned, which is currently blocking
> the more complex demos.
>
> On Jul 26, 2014, at 3:43 AM, 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
>>> >
>>>
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>>> Soc-2014-dev at blender.org
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>>>
>>
>>
>>
>> --
>> With best regards, Sergey Sharybin
>>
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-- 
With best regards, Sergey Sharybin
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