[Bf-gamedev] Triangulation Modifier changes, and feedback

[metalliandy]

Hi Dalai,

Awesome! I can't wait to see the changes in a build!

Triangulation is very important to ensure consistently correct baking 
(anyone who says different either doesn't care or doesn't know any 
better ;) ) but it is also very important to ensure that it is as 
non-destructive as possible to allow the flexibility of having to go 
back and adjust geometry without having to convert to quads which can be 
error prone and time consuming.

Quads are not needed for game ready meshes as they are converted to tris 
anyway on import but the important thing is that the triangulation is 
performed before baking and the same triangulation is used on the game 
mesh. As we can't guarantee which method of triangulation is used in any 
other program it is down to the artist to ensure that it remains 
consistent throughout the pipeline. However, in Blender triangles 
restrict the ability of the artist to edit a mesh in a fast and 
efficient manner so it isn't really a good idea to work on a 
triangulated mesh in this way.

The method of triangulation doesn't really matter from a rendering 
perspective  as GPUs can brute force pretty much anything with relative 
ease (aside from very long thin triangles) and we don't do things like 
tri-stripping any more because it's just not worth the effort for the 
extremely minimal impact of performance.

That said, shortest diagonal is the most consistent way of applications 
triangulating a mesh as the mesh will always have the same results vs 
other perhaps more involved triangulation algorithms. So having it as 
default makes sense I think.

The ability to rotate edges would be great but not at the expense of 
changing the triangulation algorithm from shortest diagonal so unless 
there is a way to do this I would prefer to do any edge rotating after 
the fact once the modifier has been applied before export.

Cheers,

-Andy

On 01/11/2013 19:27, Dalai Felinto wrote:
> Hi,
>
> I recently committed some changes to the Triangulation Modifier [1]:
>
> 1) Quads Split Method: Shortest Diagonal (default), Beauty, Fixed, 
> Fixed Alternate
> 2) Ngons Split Method: Scanfill, Beauty
>
> There is a remaining issue though. Users seem to care about 
> non-destructive workflows and at the same time, fine-tuning control 
> over the triangulation.
>
> For that the easiest solution would be to have the user triangulating 
> the quads that need to be tweaked. The downside of this is that you 
> loose things such as edge-loop/rings selection.
>
> Another solution would be changing the code to flag some edges/quads 
> as 'flip-rotation'. This is complicated to implement, leads to a messy 
> design for the user, and honestly it may not be worth the time to do it.
>
> As a compromise/3rd option one can use an addon to 'rotate' the 
> vertices indices of a face, and use it with the Fixed or Fixed 
> Alternate quad methods.
> I even implemented that in C, but it should be doable in Py as well 
> [2]. The downside of this is that it would not work with the "Shortest 
> Diagonal", which seems to be a popular method.
>
> I would like to hear from some real-world pipelines how important it 
> is to have all-quads meshes, and/or if the current 
> implementation/solutions are enough.
>
> [1]  - 
> http://wiki.blender.org/index.php/Doc:2.6/Manual/Modifiers/Generate/Triangulate
> [2] - https://github.com/dfelinto/blender-svn/pull/16/files
>
> Many thanks,
> Dalai
>
> --
> blendernetwork.org/dalai-felinto <http://blendernetwork.org/dalai-felinto>
> www.dalaifelinto.com <http://www.dalaifelinto.com>
>
>
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