[Bf-committers] Opensubdiv and catmull-clark again

Mike Erwin significant.bit at gmail.com
Fri Nov 6 08:33:53 CET 2015 

Cool, I just opened OpenSubdiv issue #757 for adaptive tessellation on
Intel.

Also have an open bug in Apple's bug tracker, re-reported as OpenSubdiv
issue #758.

Mike Erwin
musician, naturalist, pixel pusher, hacker extraordinaire

On Fri, Nov 6, 2015 at 1:12 AM, Sergey Sharybin <sergey.vfx at gmail.com>
wrote:

> Issues with upstream development branch of OpenSubdiv are to be reported to
> their github tracker [1].
>
> We will go to latest OpenSubdiv as soon as i catch up with real life after
> all this flying. Hopefully for the Monday-Tuesday we'll have updated libs
> for all the supported platforms.
>
>
> [1] https://github.com/PixarAnimationStudios/OpenSubdiv/issues
>
> On Fri, Nov 6, 2015 at 11:03 AM, Mike Erwin <significant.bit at gmail.com>
> wrote:
>
> > Hi Sergey!
> >
> > I wasn't suggesting the latest OSD should have been rushed into 2.76. But
> > definitely for the next update. I've upgraded Blender to OSD 3.0.3
> locally
> > and it fixes GLSL compute for both AMD and Intel on Windows. Adaptive
> > subdivision doesn't seem to work on Intel chips -- on Windows or Mac --
> > even with Pixar's example programs. No crash or errors; the surface just
> > doesn't appear on screen. Non-adaptive works fine.
> >
> > How soon can we bump the libs to 3.0.3? I have a few changes to the
> > Blender-OSD glue. Can those go into master or would you prefer a new
> branch
> > for the stuff I'll be working on?
> >
> > No ideas yet for the normals but I will investigate. As you know we're
> > moving to GLSL 1.5 soon so rewriting is going to happen anyway.
> >
> > Mike Erwin
> > musician, naturalist, pixel pusher, hacker extraordinaire
> >
> > On Thu, Nov 5, 2015 at 11:22 PM, Sergey Sharybin <sergey.vfx at gmail.com>
> > wrote:
> >
> > > Yury,
> > >
> > > For the original mail: OpenSubdiv and Blender original CCGSubSurf are
> > using
> > > different approaches to the patch topology construction, but both of
> them
> > > technically are Catmull-Clark subdivisions. There's no correct or wrong
> > > crease here, it's just different and behaves better in one situation or
> > > another. We'll switch to OpenSubdiv completely once all the issues are
> > > solved.
> > >
> > > For the followup mail: you're pointing out all the TODOs and
> limitations
> > > mentioned in the original release page [1]. Don't see much reason to
> > > discuss them here, we'll need to work on this still. With a project
> size
> > of
> > > OpenSubdiv and the tight release schedule we had so far you can't
> really
> > > have everything to be ideally supported from the first commit. It'll
> all
> > > come eventually.
> > >
> > > Mike,
> > >
> > > GLSL Compute is disabled for AMD devices because original OSD library
> we
> > > used for the 2.76-rc1 had a bug on AMD hardware. It was fixed later at
> > rc2
> > > or rc3 from the OpenSubdiv side, but we can't bump library versions at
> > the
> > > RC stage (bumping it will mean we're allowing to use hardware which was
> > > known to be buggy without too much tests done first).
> > >
> > > For the shading, here's the bug report [2]. I didn't find a way to
> > evaluate
> > > limit surface on the GPU when using non-adaptive subdivisions and i
> > didn't
> > > really heard back from Pixar about how it could be done. Wold need to
> ask
> > > the guys again. But OpenSubdiv 3.0 is quite fresh so far and perhaps
> > > non-adaptive case is not high priority for them yet.
> > >
> > > Perhaps we can do some other trickery to get better normals, but that'd
> > > requite having tessellation control and evaluation shaders which was
> > quite
> > > hard to do with current OpenGL state we've got. It didn't quite work
> for
> > me
> > > when trying to sue it as an #extension for glsl 1.3 and mumping glsl to
> > 1.4
> > > and higher would mean re-writting all the existing shaders (due to
> > removed
> > > of loads of deprecated stuff in it, i.e. gl_Normal). Maybe you can have
> > > some other ideas here tho.
> > >
> > > [1]
> > >
> http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.76/OpenSubdiv
> > > [2] https://developer.blender.org/T45707
> > >
> > >
> > >
> > > On Thu, Nov 5, 2015 at 10:02 PM, Mike Erwin <significant.bit at gmail.com
> >
> > > wrote:
> > >
> > > > Hi guys,
> > > > I'm actively working on OpenSubdiv, especially getting it running on
> > more
> > > > systems (Intel gfx on Windows, Mac). GLSL compute works on the latest
> > > > version of OSD (official Blender release doesn't use this yet).
> Similar
> > > > performance to Transform Feedback. The other problems you mention...
> > yep
> > > > those are still problems.
> > > >
> > > > Thanks for pointing out #2 -- I knew it looked odd but didn't make
> the
> > > > connection to low-poly normals. Can you give a link to the bug
> tracker?
> > > >
> > > > From my understanding, OpenSubdiv will become *the* subsurf
> > > implementation
> > > > in Blender, and the old system will go away. But first we need to fix
> > > these
> > > > problems.
> > > >
> > > > Mike Erwin
> > > > musician, naturalist, pixel pusher, hacker extraordinaire
> > > >
> > > > On Thu, Nov 5, 2015 at 7:52 AM, Yury Baranov <cucumberer at gmail.com>
> > > wrote:
> > > >
> > > > > Opensubdiv is unusable ATM in fact. Problems are:
> > > > > 1. Unable to apply Subsurf with OSD enabled. Result is identical to
> > > > Subsurf
> > > > > without OSD check.
> > > > > 2. Shading is wrong (bug is in the bugtracker already). OSD takes
> > > normals
> > > > > for shading from lowpoly instead of computing new normals.
> > > > > 3. No UV subdivision.
> > > > > 4. GLSL Compute is not working for me.
> > > > > OK, the feature is too new and too raw to use it in production. But
> > OSD
> > > > is
> > > > > based on Catmull-Clark algo, which is already used in the Subsurf
> > > > modifier,
> > > > > OSD is just speeding mesh calculation up. The problem is, OSD and
> > > > > Catmull-Clark subdiv models look different, it not supposed to
> happen
> > > > IMHO.
> > > > >
> > > > > 2015-11-05 15:33 GMT+03:00 Nahuel Belich <
> casillapforos at yahoo.com.ar
> > >:
> > > > >
> > > > > > intersting, in that case, as a modeler i would prefer the open
> subv
> > > > > > result, however i didnt model that much using it, the performance
> > its
> > > > > much
> > > > > > much better, but the shading its "weird" or not accurate on most
> > > cases.
> > > > > . .
> > > > > >  i need to test it more to shape an opinion
> > > > > > PasteAll.org - opensubdiv.jpg
> > > > > > |   |
> > > > > > |   |   |   |   |   |
> > > > > > | PasteAll.org - opensubdiv.jpgPasteAll.org - opensubdiv.jpg
> > > > > > opensubdiv.jpg ~0.11mb..ish. 916 px. 1335 px. |< << hi
> PasteAll.org
> > > is
> > > > > > brought to you by the monkeys of GraphicAll.org -  |
> > > > > > |  |
> > > > > > | Ver en www.pasteall.org | Vista previa por Yahoo |
> > > > > > |  |
> > > > > > |   |
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >      El Jueves, 5 de noviembre, 2015 5:09:30, Yury Baranov <
> > > > > > cucumberer at gmail.com> escribió:
> > > > > >
> > > > > >
> > > > > >  Hi. I just mentioned that Blender's subdivision surface is
> acting
> > a
> > > > > little
> > > > > > bit different than opensubdiv. It's noticable when using creases
> on
> > > > > > geometry like this: http://puu.sh/la3Xw/3c06b8b687.png
> > > > > > Blender's catmull-clark subdivs:
> > http://puu.sh/la3ZJ/a5f8ce2ddf.png
> > > > > > Opensubdiv: http://puu.sh/la40E/529b72bec5.png
> > > > > >
> > > > > > Looks like Blender's Catmull-Clark subdivs are not Catmull-Clark
> > > > > subdivs...
> > > > > > _______________________________________________
> > > > > > Bf-committers mailing list
> > > > > > Bf-committers at blender.org
> > > > > > http://lists.blender.org/mailman/listinfo/bf-committers
> > > > > >
> > > > > >
> > > > > >
> > > > > > _______________________________________________
> > > > > > Bf-committers mailing list
> > > > > > Bf-committers at blender.org
> > > > > > http://lists.blender.org/mailman/listinfo/bf-committers
> > > > > >
> > > > > _______________________________________________
> > > > > Bf-committers mailing list
> > > > > Bf-committers at blender.org
> > > > > http://lists.blender.org/mailman/listinfo/bf-committers
> > > > >
> > > > _______________________________________________
> > > > Bf-committers mailing list
> > > > Bf-committers at blender.org
> > > > http://lists.blender.org/mailman/listinfo/bf-committers
> > > >
> > >
> > >
> > >
> > > --
> > > With best regards, Sergey Sharybin
> > > _______________________________________________
> > > Bf-committers mailing list
> > > Bf-committers at blender.org
> > > http://lists.blender.org/mailman/listinfo/bf-committers
> > >
> > _______________________________________________
> > Bf-committers mailing list
> > Bf-committers at blender.org
> > http://lists.blender.org/mailman/listinfo/bf-committers
> >
>
>
>
> --
> With best regards, Sergey Sharybin
> _______________________________________________
> Bf-committers mailing list
> Bf-committers at blender.org
> http://lists.blender.org/mailman/listinfo/bf-committers
>

More information about the Bf-committers mailing list