[Soc-2017-dev] Weekly Report #10 - Silhouette Operator

[Sergey Sharybin]

Hi.

Just for the record. We've talked about mesh structure and projection in
IRC.

Conclusion about mesh: just use CustomData API to manipulate new/existing
geometry.

For projection, either use ED_view3d_project_float_v2_m4, or
maybe project_plane_v3_v3v3 dependening on what exactly is needed here. Fir
further help about projection we need to know what exactly needs to be done.

On Fri, Aug 4, 2017 at 7:39 PM, Sebastian Witt <W.Basti at gmx.de> wrote:

> *Weekly Report #10 - Silhouette Operator*
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> * In the 10th week I continued to develop the transition method to connect
> a drawn Silhouette to existing geometry. Turns out, this is a real
> challenge. I stumbled over a couple of problems. But first, let’s talk
> about What has been done in this week: - Implement an algorithm to
> calculate the edge-ring which is separating the vertices which need to be
> cut from the ones which need to stay. - Ordering of those rings - Generate
> bounding-boxes for the rings - Find intersecting rings which are the result
> of cross-node holes - Calculate the shared parts of those rings Problems,
> Questions, Challenges First things first: After this week i can say that
> the task to connect the parts is harder than expected. I am now pretty sure
> I will not be able to deliver a bug-free, tested, documented operator with
> the transition option within the GSoC timeframe. It is more complex than
> expected because of a couple of reasons: The Mesh Problem Currently I have
> used almost completely the basic mesh structure of blender. Within
> sculpting mode everything is handled by manipulating the mesh of the
> sculpt. Everything, with exception of the dyntopo mode, is limited to
> non-destructive/non-constructive mesh edits. Vertices are only deformed.
> With the silhouette operator I need to create new
> vertices/edges/loops/polys (v/e/l/p). Till now this has been no problem
> since just appending new data to the v/e/l/p arrays is easy. Maybe it is
> just because I misunderstand the customdata structure, but deleting and
> rearranging the v/e/l/p is more problematic. Additional data like vertex
> color, shape keys etc. is dependent on consistent v/e/l/p memory. There is
> almost no functions in the codebase to manipulate the base mesh structure.
> I started creating a remove vertices function which is supposed to delete
> vertices and connected edges etc. adjacent to it. I started to create
> redirection tables to redirect all the pointers. Polys -> Loops -> Edges ->
> Vertices. Even though this is possible, it breaks references to it from
> other sources. I postponed this task and wanted to get some feedback on
> these questions first. The Orthographic Matrix Earlier this week i sent a
> question in this mailing list. How do i get the orthographic projection
> matrix in perspective mode? I still don’t know how to do it, so feel free
> to have a look at it! What is the time-plan? Besides the bigger problems
> like the mesh problem the whole task has several challenges. Most of which
> i know how to tackle but need a lot of time. A random number of arbitrary
> shaped intersections between random shapes with various pixel-densities
> need to be transitioned. It is hard to say, but my optimistic guess is: If
> there is a good method for the mesh problem, I can get a running version
> with transitions in 3 weeks from now. Therefore there will be almost no
> time for testing, bug fixing or documentation. I think it is important to
> discuss now, so let me know any thoughts on this! Besides this,
> ErickBlender made a great video demonstrating the use of the silhouette
> operator! I think it shows very well how the operator is intended to be
> used. Generating a quick foundation for later refinement with the other
> sculpting tools. So have a look:
> https://www.youtube.com/watch?v=VdIV5Mb2XX4&feature=youtu.be
> <https://www.youtube.com/watch?v=VdIV5Mb2XX4&feature=youtu.be> As always,
> have a great weekend! Sebastian Witt *
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>


-- 
With best regards, Sergey Sharybin
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