Can I render a colored curves?

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Can I render a colored curves?

Postby izCG » Tue Jul 18, 2017 3:31 am

izCG Tue Jul 18, 2017 3:31 am
Hello,

Although you can do it in mantra,
I do not know how to do it in octane.
Thank you.

Thanks,
tomo
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Re: Can I render a colored curves?

Postby juanjgon » Tue Jul 18, 2017 8:23 am

juanjgon Tue Jul 18, 2017 8:23 am
Hi,

Unfortunately, Octane doesn't support custom attributes like Cd yet. Your best chance is to use and UV map to set the hair colors from a texture map.

I could also add to the hair rendering the same trick used to support the Cd attribute on the particles, encoding the attribute in the hair UVs. Should be easy. What version of Houdini are you using? I can post here a custom build with this feature to test it.

Thanks,
-Juanjo
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Re: Can I render a colored curves?

Postby izCG » Tue Jul 18, 2017 9:38 am

izCG Tue Jul 18, 2017 9:38 am
Hi and Thank You for Your quick reply!

I am using Houdini 16.0.600 and Octane Version 3.06.2.0.
Somehow I can`t figure out the right way to do it.

Could You provide an example File, or point to a Tutorial, that would be highly appreciated.
Thank You in advance
Tomo
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Re: Can I render a colored curves?

Postby juanjgon » Tue Jul 18, 2017 10:59 pm

juanjgon Tue Jul 18, 2017 10:59 pm
I have this feature near ready. I'll post the custom build tomorrow with a sample scene to test it ;)

Thanks,
-Juanjo
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Re: Can I render a colored curves?

Postby izCG » Wed Jul 19, 2017 12:35 am

izCG Wed Jul 19, 2017 12:35 am
Thank You so much! This would help me alot! Looking forward to tomorrow
Best Regards
Tomo
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Re: Can I render a colored curves?

Postby juanjgon » Wed Jul 19, 2017 11:40 pm

juanjgon Wed Jul 19, 2017 11:40 pm
This is a test build for H16.0.600 and H16.0.633 with this new feature. You can enable it in the fur options, but be aware that the Cd attribute must be set at primitive level. Octane only supports one UV coordinate per curve.

Also, like happens with this same feature in the particle systems, you need to build a shader with a texture node pointing to the texture map available in the "tex" folder, inside the plugin directory. This texture map has the encoded colors needed to render the color attributes.

https://render.otoy.com/customerdownloa ... _TEST1.zip


Thanks,
-Juanjo
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image-001677.jpg
image-001674.jpg
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Re: Can I render a colored curves?

Postby izCG » Thu Jul 20, 2017 9:56 am

izCG Thu Jul 20, 2017 9:56 am
Thank You so much for your quick response and the fix!
It works perfectly, You really saved me!
Thanks again and Happy Rendering
Tomo
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Re: Can I render a colored curves?

Postby fantome » Sat Mar 17, 2018 3:43 pm

fantome Sat Mar 17, 2018 3:43 pm
Hi guys,

i am trying to render, per point attribute color on a curves throw the uv tricks.
i do not intend to use the default tool base on prim color and the rgb4k_map.ppm.

in fact i would like to be able to render a gradient color on a single curves with only one primitive.
this method does work on curve mesh with a polywire, but it force me to convert my curves as polygon.

The problem is that i haven't find a proper workflow to have a different color for the root and the tip,
which is quite essential in a fur workflow.

I have attach a scene to describe the pb.

Octane only supports one UV coordinate per curve.

Is it still true today ? can osl help us on this ?

Cheers
E
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Re: Can I render a colored curves?

Postby fantome » Sat Mar 17, 2018 5:01 pm

fantome Sat Mar 17, 2018 5:01 pm
well i think this answer my question
viewtopic.php?f=101&t=63452

so no octane can't read uv attribute at point level to bypass, the attribute access restriction.
it can however shade root and tips by using Tool W Coordinate.

this whole attribute blindness of octane to geo att is really a real pita for houdini users.
i'm also afraid like mention in the post that the osl texture support won't help in that case.

It's kinda the never ending story for me , because i've replace Maxwell by Octane,
having spend a lot of time trying to get this feature with maxwell devs and it has never become a reality.

EDIT :

after testing, we can sucessfully shade tip and root base from texture, so that's great, i have attach a small exemple.
at the end:
- we can use Cd on a curves at prim level
- we can shade a curve with a ramp with the tool W coordinate
- we can shade root and tip base on texture with a mix texture combine with a tool W coordinate
- we can bake Cd attribute on a geo to a texture map to access them throw texture
That cover nearly all the scenarios, so that's a far better experience than Maxwell plugin for houdini.

the only scenario which is not covered is to
- rendered Cd attributes on a curves at point level.
but we can bypass this by using a polywire and the uv to attribute tricks bu using a ramp

Not perfect but still good enough ! :)

I cross my fingers for att support natively in the 3.09...
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