[Bf-cycles] uv coordinates in Cycles standalone

[Guillaume Rouault]

Sorry I didn't take time to answer you before.
 I did add the line to increment index_offset in the code. It compiled
fine, and the uv "stuttering" seems to be gone.
It seems a lot more logical like that.
But still, my uvs are messed up. First polygon is alright, but anything
after that is messed up. I must do something wrong.
I spent way to much time trying to export uvs in the right way, when they
couldn't even be rendered correctly by cycles standalone.  And now I wonder
if there are some other problems with in the source code.
 I don't think I will try again unless I see an image with working uvs ,
rendered with the standalone using XML API. ( I guess I am sort of giving
up there .... )
The fact that motion blur is not available yet is also a big issue to me.

Anyway, this little adventure has taught me a lot already. Unfortunately my
C++ skills are pretty bad. So I'm looking forward to see what awesome stuff
you guys will give us.

Guillaume Rouault

On Wed, Dec 23, 2015 at 12:45 PM, Sergey Sharybin <sergey.vfx at gmail.com>
wrote:

> This indeed seems weird and form quick glance we have to increase
> index_offset by nverts[i] at the end of the outer loop.
>
> WOuldn't have time until weekend to look deeper, mind testing such a
> modification and telling if it all works correct after the change?
>
> On Wed, Dec 16, 2015 at 1:30 AM, Guillaume Rouault <
> guillaume.rouault.fx at gmail.com> wrote:
>
>> When I look at the code here :
>>
>> https://developer.blender.org/diffusion/C/browse/master/src/app/cycles_xml.cpp;65ff373f0c71c043dd7b5632580501f1fc4bea7e$959
>>
>> what I understand is that triangles are created from the provided Ngons ,
>> and the same is done with the uvs below.
>> So data should be as simple as :
>> - a list of vertices
>> - a list of corresponding uvs.
>>
>> UV="
>> 0.0 0.0
>> 1.0 0.0
>> 1.0 1.0
>> 1.0 0.0
>> "
>> nverts="4"
>> verts="0 1 2 3"
>>
>> and indeed, it works with a simple plane with 4 vertices.
>> Problems come when I add a second polygon. What ever I do , the second
>> polygon invariably gets the same coords as the first one. Thas, I REALLY
>> don't understand.
>>
>> In cyles_xml.cpp where the uvs are created:
>>
>> /* loop over the triangles */
>>  index_offset = 0;
>> ...
>> ....
>> , is it normal that this variable index_offset is never incremented
>> during the loop?  Isn't looping over the same polygon over and over ?
>> (which would explain the uv "repetition" )
>> Can somebody confirm if I am right or wrong ?
>>
>>
>> Guillaume
>>
>> On Tue, Dec 15, 2015 at 4:00 PM, Nathan Letwory <nathan at mcneel.com>
>> wrote:
>>
>>> -----BEGIN PGP SIGNED MESSAGE-----
>>> Hash: SHA256
>>>
>>> Hi Guillaume,
>>>
>>> Ah, I forgot that in my XML importer implementation (C#) I convert
>>> quads to triangles. I'm looking at nverts, then if it is 4 I add two
>>> triangles instead of one quad. Excuses about that.
>>>
>>> I don't know precisely how the C++ XML import is written, you'll have
>>> to check the code for that.
>>>
>>> /Nathan
>>>
>>> On 14/12/2015 18:02, Guillaume Rouault wrote:
>>> > Hi again,
>>> >
>>> > @Nathan, you mentionned to me somewhere that uvs a listed by
>>> > triangles, but in the example file you gave me:
>>> > https://github.com/jesterKing/CCSycles/blob/master/tests/objects/uv_cu
>>> be.xml
>>> <https://github.com/jesterKing/CCSycles/blob/master/tests/objects/uv_cube.xml>
>>> >
>>> >  uvs are clearly listed by squares ( 6 of them of course)
>>> >
>>> > To be honest, I have really hard time exporting my uvs from
>>> > houdini. I've tried a lot of things already, and nothing seems to
>>> > work, I am on the verge of giving up frankly, which would be a
>>> > shame, because uvs are my last main issue, I have almost a basic
>>> > working solution for simple animations rendering with houdini.
>>> >
>>> > Guillaume
>>>
>>>
>>> - --
>>> Nathan Letwory
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>>
>>
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>
>
> --
> With best regards, Sergey Sharybin
>
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