[Bf-cycles] uv coordinates in Cycles standalone

[Guillaume Rouault]

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_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

On Thu, Dec 10, 2015 at 1:14 PM, Guillaume Rouault <
guillaume.rouault.fx at gmail.com> wrote:

> After reflection, It's dumb of me to think that the error comes from
> source code. It definitely comes from my python code :
> I was able to render correctly the example object you gave me 'uv_cube.xml'
>
> Guillaume
>
> On Thu, Dec 10, 2015 at 12:45 PM, Guillaume Rouault <
> guillaume.rouault.fx at gmail.com> wrote:
>
>> Thank you guys for your answers, I wanted some infos, and I have plenty
>> of them now ^^ .
>> I am trying to code a exporter from Houdini to Cycles Standalone. I use
>> python to do that in houdini 15.
>> The fact is , I am really bad at C++ and after several hours of reading
>> the source code, my head hurts a little ^^ .
>>
>> indeed a lot of infos in cycles_xml.cpp
>> I adapted my export script to try and mimic the way mesh is computed.
>>
>>  in the part of the code you mentionned
>> https://developer.blender.org/diffusion/C/browse/master/src/app/cycles_xml.cpp;65ff373f0c71c043dd7b5632580501f1fc4bea7e$982
>>
>> Is it normal that the variable 'index_offset' stays at 0 ?
>> Shouldn't it be incremented at every iteration ?
>>
>> Guillaume
>>
>> On Thu, Dec 10, 2015 at 6:42 AM, Nathan Letwory <nathan at mcneel.com>
>> wrote:
>>
>>> -----BEGIN PGP SIGNED MESSAGE-----
>>> Hash: SHA256
>>>
>>> I haven't actually tested this in the C++ standalone version, but only
>>> in my C# CCSycles tester, but check out
>>>
>>> https://github.com/jesterKing/CCSycles/blob/master/tests/objects/uv_cube
>>> .xml
>>> <https://github.com/jesterKing/CCSycles/blob/master/tests/objects/uv_cube.xml>
>>>
>>> You'll have to add a texture coordinate input node and connect it to
>>> the image texture node (vector). That should have your shader use UV
>>> coordinates from the mesh data.
>>>
>>> UV coordinates are per triangle (you can double-check here:
>>> https://developer.blender.org/diffusion/C/browse/master/src/app/cycles_x
>>> ml.cpp;65ff373f0c71c043dd7b5632580501f1fc4bea7e$982)
>>>
>>> Here a custom RhinoCycles material using XML with a texture coordinate
>>> input node:
>>> https://github.com/mcneel/RhinoCycles/blob/master/Materials/BrickWithChe
>>> ckeredMortar.cs
>>>
>>> And here for the C#-way of creating nodes in RhinoCycles where I set
>>> projection and mappings
>>> https://github.com/mcneel/RhinoCycles/blob/master/RenderEngine.Utils.cs#
>>> L131
>>> <https://github.com/mcneel/RhinoCycles/blob/master/RenderEngine.Utils.cs#L131>
>>> - - in this function the last else block is probably the most
>>> interesting, since here I connect the UV output from texture
>>> coordinate input node :)
>>>
>>> Hope that helps,
>>>
>>> /Nathan
>>>
>>> On 09/12/2015 23:42, Guillaume Rouault wrote:
>>> >
>>> > I couldn't find a file named blender_mesh.cpp in the sources I
>>> > have. And I think it would mainly give me some infos on how to
>>> > format the mesh in the xml object file. but my main issue, I think,
>>> > is at the shader level in the scene xml file, using the standalone
>>> > XML API . How do I force the shader to use uv coordinates provided
>>> > on the mesh ?
>>> >
>>> > Now that I think of it, there are no examples using uv mapped
>>> > objects in the /examples folder, at least nothing using coordinates
>>> > generated during modeling.  Is it even supported at this stage in
>>> > the standalone version ?
>>> >
>>> > Guillaume
>>> >
>>> > On Wed, Dec 9, 2015 at 10:19 PM, Mohamed Sakr <3dsakr at gmail.com
>>> > <mailto:3dsakr at gmail.com>> wrote:
>>> >
>>> > in blender_mesh.cpp, find attr_create_uv_map() function and see
>>> > how they create UVs
>>> >
>>> > On Wed, Dec 9, 2015 at 10:26 PM, Guillaume Rouault
>>> > <guillaume.rouault.fx at gmail.com
>>> > <mailto:guillaume.rouault.fx at gmail.com>> wrote:
>>> >
>>> > Hi,
>>> >
>>> > I can't find any infos on uv coordinates for cycles standalone. As
>>> > of now, I haven't been able to render an object with the correct
>>> > uvs. I can see a texture, but it's mapped to every triangle on the
>>> > mesh.
>>> >
>>> > I searched the xml api , and came up with that setup :
>>> >
>>> >
>>> > *<!-- floor shader-->* *<shader name="floor" >* *<diffuse_bsdf
>>> > name="diffuse" roughness="0.05" color="1.0, 1.0, 1.0" />*
>>> > *<glossy_bsdf name="glossy" roughness="0.05" color="0.2, 0.2, 0.2"
>>> > />* * * *<texture_coordinate name="uv" />* *<image_texture
>>> > name="tex" src="./maps/aaa.jpg" />* *<add_closure name="mix" />*
>>> > *<fresnel name="fresnel" />* *<connect from="fresnel fac"
>>> > to="glossy color" />* * * *<connect from="uv uv" to="tex vector"
>>> > />* *<connect from="tex color" to="diffuse color" />* * * * *
>>> > *<connect from="diffuse bsdf" to="mix closure1" />* *<connect
>>> > from="glossy bsdf" to="mix closure2" />* *<connect from="mix
>>> > closure" to="output surface" />* *</shader>* * * * * Am I on the
>>> > right path ? * * Are there any examples or infos on uvs somewhere
>>> > ? Actually, on my meshes,  I don't even know if I have to export uv
>>> > coords as vector2  (uv) , or vector3 (uvw) ? * * * * *Guillaume*
>>>
>>>
>>> - --
>>> Nathan Letwory
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>>
>>
>
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