Principled Shader / Opacity / Alpha - how does it work?

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Hello to you guys,

I am just desperate right now. I want to create a principled shader with a texture. The texture is a TIF and has an alpha channel (transparent PNG is the same).
My understanding from programs like MAX or MAYA is, that if I use a texture with an alpha channel, the object is transparent, where the alpha channel is black, and is opaque, where the alpha channel is white - showing the color of the map.

Attached you´ll find a Screenshot of the viewport and a testrendering (from Maya) how it should look like.





I just can´t get this to work in Houdini.
Can anybody help me or explain what I am doing wrong?
I searched the web and can find some help, but they are more or less older and not 1:1 the problem I have.
I am using 18.5.382-Indie.

If there is a good tutorial out there, dealing with textures and explaining how it works, I´d be very happy.
Edited by 3dclassen - 2020年11月19日 04:48:15

Attachments:
HOUDINI_ShaderOpacityAlpha_Testrendering.jpg (37.0 KB)
HOUDINI_ShaderOpacityAlpha_Viewport.jpg (86.2 KB)

Daniel Classen
Co- Founder & CEO

LIGHTSHAPE gmbh & co. kg
schockenriedstraße 4
70565 stuttgart
tel: +49 711 219 578 0

https://www.lightshape.net [www.lightshape.net]
https://www.lightshape.net/blog/ [www.lightshape.net]
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When loading the texture with the texture VOP, at the top you can change the Signature to “RGBA”, so the output is a vector4 (rgb + a). With a “vector4 to vector” VOP, you can split it, put the rgb vector in for example the basecolor of the princshader and the alpha (float) in the opac input under Opacity.

I added an example file with a texture.

Also greetings from Stuttgart!
Edited by David Krepelka - 2020年12月9日 17:06:45

Attachments:
opacity_shader.hipnc (582.0 KB)
test_texture_with_alpha.tif (6.0 MB)
render.JPG (51.3 KB)

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Hi David,

thanks a lot for the reply, that´s exactly what I was looking for!
I am wondering, why some “easy” tasks are so complicated in Houdini, but I anyway like the program a lot to get deeper into it.

Thanks again, I appreciate your help!
Daniel
Daniel Classen
Co- Founder & CEO

LIGHTSHAPE gmbh & co. kg
schockenriedstraße 4
70565 stuttgart
tel: +49 711 219 578 0

https://www.lightshape.net [www.lightshape.net]
https://www.lightshape.net/blog/ [www.lightshape.net]
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