Q about principled shader

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How can i create a shader, using Principled shader, in Houdini 15.5, where some parts of the model are..shiner than other parts?

I tried to use texture in Roughness and Reflect slots..without luck. Reflect seems to be on/off switch, where 0 is off, and all other values are on. Texture does not seem to do anything.

If i use Mantra Surface, i can do it by placing texture in to Reflect Base, Color slot..tho not sure if this is the correct way, but it seems to work.

The screenshot shows what i am trying to do: parts of the planks are..shiner thatn other parts. Attached file contains Mantra shader that..works, and Principled shader that does not.

Few words about the textures that are used in the scene file: i am using free sample textures from the Arroway. I don't think that i can distribute them, so here is the link for the page:
https://www.arroway-textures.ch/en/textures/boards-001?browser [arroway-textures.ch]

And here is direct download link for the RAR:
https://arrowaytextures.s3.amazonaws.com/downloads/browser/arroway-textures_boards-001.rar [arrowaytextures.s3.amazonaws.com]

Cheers
-kimmo

Attachments:
image.png (806.9 KB)
wood.hipnc (412.5 KB)

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Hi Kila,

Sorry I can't help you directly, but I have seen some tutorials that you might be able to “tweak” to get what you want.

I looked briefly at parts of Ari Danesh tut here - https://www.sidefx.com/tutorials/lesson-3-custom-shaders/ [sidefx.com]

And with a ‘ramp’ he is able to vary the color, maybe you can substitute color with texture?

In this tutorial which I did view entirely recently ( although its a paid tuturial ).

The author is able to define the height of the grass(texture) with his setup.

I'm pretty sure you could modify this tutorial to get what you want.

The tutorial is by John Moncrief and explains things in a way that makes it very easy to follow along with and understand.

Good luck.
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Hi, I'm not sure if this would help.. I looked inside the Principled Shader and tried to piece together something simpler.
Hopefully it is at least close to the result of the MS version.

Check out the VOP inside ps_planks_2. It uses Physically Based Shader VOPs like the Principles Shader. I added coloring and notes, maybe you could use this as a starting point?
Edited by galagast - Oct. 18, 2016 11:40:32

Attachments:
ps_plank_2_vops.JPG (21.6 KB)
ps_plank_2_result.JPG (20.5 KB)
wood_v2.hipnc (612.3 KB)

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Thanks Jlim! I'm a bit surprised if Principled shader doesn't support this without hacking it first.

-kimmo
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Hi, I use both the Principled Shader and Mantra Shader quite a bit so I've had a look at your scene.

There is some key factors that are affecting the results you are seeing.

1. A Roughness Map is White = 1 Roughness Value (not shiny), Black = 0 Roughness Value (shiny). When using the Principled Shader, the Roughness value (slider) seems to determine the strength of the texture used. ie. If you want to use just the roughness values of the texture, set this to 1. However, As your texture map is mostly black, changing from 0.3 to 1 won't show much difference as both result in values closer to 0 (shiny). To fix this, decide what should be shiny and adjust the map (inverting the texture works as a quick example)

2. The Mantra Surface roughness works pretty much the same. The difference here is that you are using a texture in the Reflect Colour. (often used for metallic materials in a Spec/Gloss workflow) Whilst this works to show some difference in your texture, it'll probably need tweaking to work with other textures and lighting etc. I'd recommend looking into Spec/Gloss and/or Metal/Roughness texturing workflows so you can use PBR with more expected results and avoid endless tweaking.

3. The Principled Shader has the benefit of being useful in a Metal/Roughness workflow and I'd recommend looking up information on this as it simplifies a lot of texturing.

4. The Mantra Surface is a little quicker to render, has extras like refraction etc but doesn't work as well in a Metal/Roughness workflow. (at the moment, your MS Shader is not using either workflow)

Hope this helps
Rob
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Thank you Rob!

-kimmo
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