[Soc-2017-dev] Weekly Report #07 - Silhouette Operator

[Sebastian Witt]

Hi Sergey,

you are right, it is not finished. What i was trying to say is that it 
doesn't need any new features or methods to generate the geometry.
It is just the methods present need some bugfixes.

Bugs i can currently identify:

 1. T-intersection center quads are Tris (holes in the geometry)
 2. Intersections disappear/ are placed in infinity (division by 0 or
    non-initialized memory access)
 3. T-intersection rotation out of order

The normal orientation should be an easy fix because the algorithms 
already support flipping and calculating the orientation of a polygon is 
a common problem.

I hope this clarifies what i was trying to say,


Sebastian Witt


On 16.07.17 13:29, Sergey Sharybin wrote:
> Hi,
>
> When you mention that used one method which is better than other one, 
> it is always a good idea to show two pictures: one with old method and 
> one with new one. This helps quantifying how much better results from 
> user perspective.
>
> What i didn't understand is: you're mentioning that geometry is fully 
> generated and algorithm is finished, but in the next sentence you say 
> that there are lots of issues. So either something is not finished or 
> there shouldn't be issues.
>
> Is the normal orientation the only problem now?
>
> On Thu, Jul 13, 2017 at 7:54 PM, Sebastian Witt <W.Basti at gmx.de 
> <mailto:W.Basti at gmx.de>> wrote:
>
>     Weekly Report #07 - Silhouette Operator
>
>     I am sending my weekly report a little earlier this week because I
>     am heading for an earlier weekend so i will be missing the friday.
>     I tried to do some extra hours on monday and tuesday to get some
>     extra progress and will do so in the next week as well.
>
>     Nevertheless i made some good progress this week. Last week I
>     decided to rework the geometry generation of the silhouette operator.
>
>     The unified interpolation Method
>     The major advantage of the new system is a unified interpolation
>     method.
>     The method decides the shape of the object in the 3rd Axis which
>     is not defined by the sculptor. Therefore i can easily control the
>     whole output by altering this method.
>     Currently it controls the smoothness and depth of the generated
>     geometry. The smoothness is a value between 0 and 1.
>     With 0 being an object with sharp edges. If you draw a circle for
>     example this result in a cylinder.
>     A smoothness value of 1 will smooth out the corner and results in
>     a sphere.
>
>     Order of Generation
>     Before the rework the different parts were relying on each other.
>     In other words, i generated tube-parts first carried bordering
>     edges/vertices over and generated T-intersections as well as
>     Cap-parts afterwards. Due to this dependency i had to incorporate
>     a lot of corner cases and experienced a lot of unexpected
>     behaviour. With the new system every part is self-contained and
>     exposes only one continuous edgeloop. This makes it easier to
>     track done errors and is a cleaner approach in general.
>
>     Connecting the Parts
>     With those continuous edgeloops it is easier now to connect the
>     different parts. There is still some issues with the general
>     orientation of some parts and inverted edgeloops. But that should
>     not be a big problem to solve.
>
>     What is the current stage?
>     In theory the geometry is now completely generated. The algorithm
>     itself is done! In practice there are still a lot of issues with
>     the system. As mentioned above the part orientation is messed up
>     sometimes resulting in errors on the connections.
>
>     What is up next?
>     Next step is to fix the issues and make the tool a little more
>     stable. After that i will try to fix the normal orientation.
>     Currently if drawn counterclockwise it is correctly oriented and
>     if drawn clockwise the normals need to be flipped.
>     If the silhouette is more stable I will start exposing the tool
>     settings and hopefully move on soon to connecting to existing
>     geometry.
>
>     Best regards,
>
>     Sebastian Witt
>
>
>     _______________________________________________
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>
>
>
>
> -- 
> With best regards, Sergey Sharybin
>
>
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