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

[Howard Trickey]

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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