[Bf-committers] Blender developers meeting notes - August 2, 2015

Antony Riakiotakis kalast at gmail.com
Mon Aug 3 00:54:51 CEST 2015

What might work is detecting if the final derived mesh has any users
outside the draw code, and if it does not then it may be possible to
use some sort of shader and do the calculation there. If it does, then
we will be needing the full result anyway, so we can just upload that
and skip the vertex shader cost. Some modifiers, such as the array
modifier can also benefit from similar code (+ instancing) but they
also need a way to detect cornercases (such as the object used as a
duplicated mesh for instance).

I must say though, I am not sure if using vertex shaders is the best
way to go, because it makes material shaders depend on modifiers which
means more shader bind calls plus materials would need a more
elaborate shader storing scheme for every material/modifier
combination. Maybe the way OpenSubdiv handles this can be generalized,
but we'll see if that's possible when/if we have full support in the

Probably the depsgraph might support these kinds of queries, though
Sergey, Lukas or Joshua would know best.
The DAG should also be used to detect what mesh data need to be
reuploaded to the GPU due to some underlying mesh change
as well. Currently though, I'm still porting all mesh code to use
vertex buffer objects properly and haven't checked the depsgraph at

On 2 August 2015 at 19:07, joe <joeedh at gmail.com> wrote:
> Who's doing the viewport optimization work?  I have some experience here.
> The key thing is to limit OpenGL commands, and also the data sent per-frame
> to the GPU.  It might also be a good idea to move the simpler deform
> modifiers into vertex shaders (and make sure to use a node system--it's
> actually easier to use a DAG system than to try and code all the edge cases
> by hand).
> On Sun, Aug 2, 2015 at 9:16 AM, Ton Roosendaal <ton at blender.org> wrote:
>> Hi all,
>> Here are the notes from today's meeting in irc.freenode.net
>> #blendercoders.
>> 1) Upcoming 2.76 release
>> - OpenSubdiv: an essential fix was made by the Pixar team, we we can move
>> on. (3.0.1 will be out soon).
>> Unfortunately 3.0 has no UV texture support yet, will be in 3.1 later this
>> year.
>> For that reason Sergey will add it as optional choice, mainly for
>> animation editing and playback
>> in viewport.
>> - Still waiting for a short document outlining the viewport Mesh
>> performance work.
>> - Reminder: anyone who wants to add something that affects users or other
>> developers (APIs):
>> always make a nice doc! *Before the commit* Even when you think it's not
>> interesting (like optimizing).
>> Blender work is interesting to share by default! :)
>> - Due to holidays (2+ weeks absence of several core devs) we also extend
>> the 2.76 with two weeks.
>> - Current projects and planning:
>> http://wiki.blender.org/index.php/Dev:Doc/Projects
>> - Splash: suggested is to do a public contest in BA forums again. Still
>> need a proposal for
>> who will do the judging... and would we do a theme again? Tradition is to
>> have the previous
>> team/panel who selected a splash appoint the next. I'll ask the artists
>> here to propose something.
>> - Kevin Dietrich: OpenVDB patch is still waiting for review. There are
>> also two (small) Cycles
>> features using OpenVDB ready. The platform maintainers have to check on
>> inclusion of new libs though.
>> Check this:
>> http://wiki.blender.org/index.php/User:Kevindietrich/OpenVDBRendering
>> And this:
>> http://wiki.blender.org/index.php/User:Kevindietrich/OpenVDBSmokeExport
>> Laters,
>> -Ton-
>> --------------------------------------------------------
>> Ton Roosendaal  -  ton at blender.org   -   www.blender.org
>> Chairman Blender Foundation - Producer Blender Institute
>> Entrepotdok 57A  -  1018AD Amsterdam  -  The Netherlands
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