[Bf-committers] Normal Editing Tools (GSOC 2016)

[Bastien Montagne]

Hi Stefan,

Answered mostly already in IRC and with comments on draft gdoc (suggest 
you share the link here, others might be interested to check too).

Just adding here some more general info about custom normals in our code:
* They are stored as some kind of diff from vertex (aka smooth) normals, 
more precisely, we define a 'loop space' and store custom normals in 
those as two factors (read code for more details). This allows us to 
keep (to some limited extent!) meaningful normals even with deformed 
geometry.
* However, they are broken once you change the mesh topology, to support 
this you'll need to switch to temp 'full vector' representation.

So you'll have to decide when to use 'encoded' form of normals in BMesh, 
and when to manipulate raw vectors.

* As commented, deciding how we allow to control face corners' normals 
(UI wise and code wise) is a crucial design topic that should be tackled 
very early (do we define a new selection mode? a new edit mode? etc.)

Would also suggest you create your draft on google site asap, easier to 
handle all review/interaction in one place ;)

Cheers,
Bastien


Le 20/03/2016 19:16, Stefan Büttner a écrit :
> Hey there,
>
> I am interested in the Normal Editing Tools project for GSOC 2016.
> This topic has been discussed on blenderartists ([1], [2], [3]) and
> requested heavily in the past.
> So, I stumbled over several add-ons ([4], [5]) and [Blend4web] [6] which
> address this topic already.
> In order to collect additional material on the topic (implementations
> discussions, feature requests, etc.), I was wondering if you guys could
> provide me with more information that you found or know of.
> Concerning feature ideas, I thought about looking at other software like
> [Softimage] [7], Maya or 3Ds Max in addition to the requests in various
> forum discussions.
> Implementation-wise I read about [BMeshes] [8] but still need to
> understand how they integrate into blender (especially if it's the only
> mesh data structure).
>
> Cheers,
> Stefan
>
> [1]:
> http://blenderartists.org/forum/showthread.php?284736-Normals-Editing-in-Blender
> "Discussion on Blenderartists, 2013-2015"
> [2]:
> http://blenderartists.org/forum/showthread.php?251402-Addon-Recalc-Vertex-Normals
> "Add-on for Blender, 2012-2013"
> [3]:
> http://blenderartists.org/forum/showthread.php?225925-Edit-vertex-normals-by-Phyton
> "2011"
> [4]: https://github.com/isathar/Blender-Normal-Editing-Tools "Add-on for
> blender, Oct. 2015"
> [5]: https://github.com/isathar/Blender_UDK_FBX_Tools
> [6]: https://www.blend4web.com/en/article/131/ "Blend4Web Normal Editing
> Tools, June 2015"
> [7]: https://youtu.be/iH3p8N7qbv8 "Example of Softimage Normal Editing
> features"
> [8]: https://wiki.blender.org/index.php/Dev:Source/Modeling/BMesh/Design
> "Design Notes of BMeshes"
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