[Soc-2017-dev] vertex paint project - ply exporter

Howard Trickey howard.trickey at gmail.com
Mon Jul 17 19:36:06 CEST 2017 

Good that you have isolated the problem to a display issue. I will see if I
can figure out later what is going on.  I still suspect it might be
backfaces.  Meanwhile, you should move onto other things, like the speed
issue investigation.

The things you see printed on the console are from a stray debugging printf
that you left in do_vpaint_brush_draw_task_cb_ex (which you should remove
and commit).

On Mon, Jul 17, 2017 at 1:26 PM Darshan kadu <darsh7807 at gmail.com> wrote:

> Hello, Mr. Howard,
>
> Today as you said before I tried to print the values of colors at various
> location, but again no result.
>
> Well, during the whole process it was always found that the color was
> getting assigned to the vertices correctly.
>
> What I think is there might be the problem in the 3d window as you mention
> in #case 2, almost at all the places alpha was being considered whenever
> col was used.
>
> If the subdivider would have used some different interpolation method then
> the final color would also have been different, but after printing it is
> same as other if we give all of them the same color. So what exactly
> happening is the final vertices have the same color along with alpha but
> the 3d display is different.
>
>  Also, if we subdivide the darker face which forms after the subdividing
> it gets the same color(confused).
>
> I don't know why this happens (this may be the reason), that when we run
> the blender as " blender.exe --debug", while vertex painting we see the ",
> ," and occasionally 1 getting printed on the command prompt., (may be this
> might be the reason for the slowness?) I will look into more detail of it.
>
> Thank you.
>
> On Mon, Jul 17, 2017 at 10:30 PM, Howard Trickey <howard.trickey at gmail.com
> > wrote:
>
>> Hi Darshan,
>>
>> Did you make any progress on discovering the problem with the values
>> after subdividing?  I haven't had time to look myself.  Though I did have
>> several thoughts:
>> 1) maybe the subdivide code uses some special purpose code in some cases
>> in order to do the interpolation?
>> 2) maybe the final values after subdivide are actually right but the
>> display in the 3d window is somehow wrong?
>> To see if it is (2), I'd been tinkering with the idea of having a
>> debug-mode way of seeing the loop colors as (r,g,b,a) displayed on the
>> screen, to help easily diagnose problems like these. I might send you a
>> patch for this tonight. One way in which the 3d window display might be
>> wrong: what if we are somehow seeing backfaces rendered differently through
>> the partially-transparent faces?
>>
>> If you are truly blocked without any ideas, you should probably move on
>> to something else while so that you are at least accomplishing something.
>> One suggestion would be to look at the complaint of someone in BA that said
>> that this branch seems much slower than when before you started your work.
>> A possible reason for this is that the BLEND mode you just added makes
>> things a lot slower, so you could try with and without that enabled, on a
>> model with a very large number of vertices, and see if it makes a
>> noticeable speed difference.
>>
>> On Sun, Jul 16, 2017 at 9:28 PM Howard Trickey <howard.trickey at gmail.com>
>> wrote:
>>
>>> Darshan,
>>>
>>> I too am puzzled because, as you say, the alpha channel does seem to be
>>> interpolated properly.
>>>
>>> One way to debug things like this is to keep printing out the vertex
>>> color layer at various points in execution and see where it seems to go
>>> wrong.  I think you should try for a bit to debug this yourself rather than
>>> have me do it.  If you can't solve it in a day or two, I will try to help.
>>>
>>> On Sun, Jul 16, 2017 at 2:26 PM Darshan kadu <darsh7807 at gmail.com>
>>> wrote:
>>>
>>>> So, I found the function layerInterp_mloopcol in the file
>>>> source\blender\blenkernel\intern\customdata.c which is getting called if
>>>> you do subdivide. The interesting thing is it is using the alpha channel,
>>>> also as I said in previous mail, after printing the values of all the
>>>> vertices with the same color and alpha the values printed of RGBA were
>>>> same, this means that values of color to the vertices are getting assigned
>>>> properly along with alpha. So, this creates more confusion.
>>>> What do you think?
>>>>
>>>> On Sun, Jul 16, 2017 at 6:18 PM, Howard Trickey <
>>>> howard.trickey at gmail.com> wrote:
>>>>
>>>>> Ah, now I understand, I think. So what seems to be happening is that
>>>>> the part of Blender that gets attributes for new vertices created by
>>>>> geometry operations - which typically interpolate values between the values
>>>>> of old vertices, is probably only interpolating 3 channels of color and not
>>>>> 4. See if you can find the part of the code that interpolates values in
>>>>> custom layers. If you can't, I'll give you a hint after I get back to my
>>>>> computer later.
>>>>>
>>>>> On Sun, Jul 16, 2017 at 8:34 AM Darshan kadu <darsh7807 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> I divided the mesh by subdivide option in the toolshelf on the left
>>>>>> side in the edit mode.
>>>>>>
>>>>>> On 16-Jul-2017 5:42 PM, "Howard Trickey" <howard.trickey at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Darshan,
>>>>>>>
>>>>>>> I'm away from computer until later today, so can't check this right
>>>>>>> now. But I thought when I tried a few days ago that when I added a
>>>>>>> subdivision modifier, I saw drawing done by some function in subsurf_ccg.c.
>>>>>>> Did you subdivide some other way?
>>>>>>>
>>>>>>> One way you can discover for yourself which function is drawing the
>>>>>>> faces is to start single stepping in a debugger after hitting a breakpoint
>>>>>>> in draw_mesh_paint.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Sun, Jul 16, 2017 at 7:37 AM Darshan kadu <darsh7807 at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Hello, Mr. Howard,
>>>>>>>>
>>>>>>>> I am still not able to figure out why some faces have different
>>>>>>>> color.
>>>>>>>> As, you said that it is an only one case, but other cases
>>>>>>>> like emDM_drawMappedFaces this is used in edit mode and I didn't see
>>>>>>>> control getting in it while in vertex mode, same goes with
>>>>>>>> the ccgDM_drawMappedFaces.  So, this two may not be the reason for this
>>>>>>>> behavior.
>>>>>>>>
>>>>>>>> I printed out the colors of the vertices, here also all the
>>>>>>>> vertices had the same color if i assign them the same color along with the
>>>>>>>> alpha.
>>>>>>>>
>>>>>>>> I tried glEnable to blend for both the conditions i.e.
>>>>>>>> setDrawOptions NULL and non-NULL . Still no output.
>>>>>>>>
>>>>>>>> If we look at the Fabio's patch, he added glEnable to
>>>>>>>> the cdDM_drawFacesTex_common but control don't go in that function if  we
>>>>>>>> are in solid mode. How Fabio would have handled this problem?
>>>>>>>> It works properly for alpha 0 and 255 but not for intermediate
>>>>>>>> values.
>>>>>>>>
>>>>>>>> Can the way in which mesh gets divided be the reason for it?
>>>>>>>> Thank you ,
>>>>>>>>
>>>>>>>>
>>>>>>>> On Fri, Jul 14, 2017 at 4:24 PM, Howard Trickey <
>>>>>>>> howard.trickey at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> Darshan,
>>>>>>>>> The changes I suggested were just a start to get it working in the
>>>>>>>>> most basic case. Good that you got the basic alpha display working!
>>>>>>>>>
>>>>>>>>> So far, you changed cdDM_drawMappedFaces, which is used to draw
>>>>>>>>> the faces for a basic type of derived mesh. But there are other kinds of
>>>>>>>>> derived meshes too, and you should try to figure out how to change those
>>>>>>>>> too, if you can.  Search for drawMappedFaces in the blenkernel/intern
>>>>>>>>> directory and you will see the other versions of the drawing function. When
>>>>>>>>> you add a Subdivision Surface modifier, the drawing function will
>>>>>>>>> be ccgDM_drawMappedFaces in subsurf_ccg.c .  See if you can figure out
>>>>>>>>> yourself how to change the function. See if you can figure out in what
>>>>>>>>> circumstances other versions of the drawMappedFaces function are called,
>>>>>>>>> and whether or not you think those are important cases to fix.
>>>>>>>>>
>>>>>>>>> Another case where the current code doesn't work for displaying
>>>>>>>>> alpha is when you have pushed the 'Face selection used for masking' or
>>>>>>>>> 'Vertex selection used for masking' buttons in vertex paint.  You may want
>>>>>>>>> to see if you can figure out how to fix those cases too.
>>>>>>>>>
>>>>>>>>> I put some hints on how the drawing code works in the basic case
>>>>>>>>> in our shared notes, doc,
>>>>>>>>> https://docs.google.com/document/d/1SX6ASWpYPoJ3EYJri8bX3BfXC5e-mOmraZkKMH8z4_U
>>>>>>>>>
>>>>>>>>> You can generally figure out stuff like this yourself by putting
>>>>>>>>> breakpoints at interesting places in the code and step through from the
>>>>>>>>> breakpoints, to see what code is called, what direction tests go, etc.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Fri, Jul 14, 2017, 5:00 AM Darshan kadu <darsh7807 at gmail.com>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> Hello, Mr. Howard,
>>>>>>>>>>
>>>>>>>>>> I have pushed the suggested changes. It is working properly for
>>>>>>>>>> the meshes without subdividing.
>>>>>>>>>> But after the subdivide it is giving the rectangularly shaped
>>>>>>>>>> spots. I tried, but I am not getting any hints. What can be happening?
>>>>>>>>>>
>>>>>>>>>> Thank you,
>>>>>>>>>>
>>>>>>>>>>
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