topic Re: layer rgba in Arnold for Cinema 4D Forum

layer rgba

eldajanimahdi — Tue, 22 May 2018 22:48:26 GMT

Hi I am doing really a simple scene and i want to use the layer rgba to use the alpha channel and manipulate it but it doesn't work i searched on the net but i always see that in the version 5 there is a layer but my version 5.1 there is layer rgba and two another layers like layer shader....but I am talking now about layer rgba how to use it with the alpha channel without using blend mode because blending mode change the original colors of my texture...the scene is a wall like in solidangle example and I want to put lot of textures on it...the question is how to use the alpha channel normally without blend mode the default mode is set to over??...like on Nuke you copy alpha and premult and then the merge over is simple as that. . i think it s a bit complicated. thank you very much

Re: layer rgba

Anonymous — Wed, 23 May 2018 00:06:11 GMT

Layer shader is built for mixing shader/texture without blending mode
Layer rgba is built for mixing shader/texture with blending mode and Alpha Channel operation
You can create very complex shader network when mixing both Layer Rgba and Layer Shader
Here is the doc for Layer Rgba:https://support.solidangle.com/display/A5AFMUG/Layer+RGBA
and here is the doc for Layer Shader:https://support.solidangle.com/display/A5AFMUG/Layer+Shader

Re: layer rgba

eldajanimahdi — Wed, 23 May 2018 17:26:15 GMT

Thanks for your answer, excuse me I am new on Arnold but I didn't find it obvious to cut my first texture with an alpha and put it on the other texture by using layer rgba and blending mode .... I finally did it on photoshop and export it as png ...I don't know I have to search more to do it on arnold without a third party... thanks Rachid anyway

Re: layer rgba

eldajanimahdi — Wed, 23 May 2018 19:54:10 GMT

Is there is a way to cut a texture with an alpha and then merge it over another texture on arnold?

Re: layer rgba

Anonymous — Thu, 24 May 2018 00:09:29 GMT

I did not understand the meaning of your question? are you asking if you can move alpha form one texture to other texture?
if that what you mean, the answer is yes
just use mask operation in the second layer(in this case I used ramp, but you can use any texture)

and here with layer 2 disabled

Re: layer rgba

eldajanimahdi — Thu, 24 May 2018 12:11:27 GMT

Yes this is my question but it didn't work ...I did the same ..I am using Cinema 4d not maya ....I used the alpha output of the rgba layer it didn't work and I tryed the main output of the rgba layer it didn't work

Could you show me the same example on cinema 4d please thanks

Re: layer rgba

eldajanimahdi — Thu, 24 May 2018 12:55:13 GMT

It's a black and white texture an alpha map .... could we use it?

Re: layer rgba

eldajanimahdi — Thu, 24 May 2018 13:24:48 GMT

and then I want to put the result on a third different texture ...

When I use multiply and I put the third texture it changes my colors I can't find the right blending mode to put several texture over each others while using alpha ...

Re: layer rgba

Anonymous — Thu, 24 May 2018 14:34:24 GMT

are you reading this from preview post?
use MASK operation for the second Layer

layer disabled

Re: layer rgba

peter.horvath6V6K3 — Thu, 24 May 2018 14:35:12 GMT

The over, etc. blending modes uses the alpha channel of the input image. Since you have a separate alpha, I think what you need it to connect the alpha image to the Mix parameter of the second layer and choose the overwrite operation.

Re: layer rgba

Anonymous — Thu, 24 May 2018 14:43:37 GMT

He want to use the alpha channel from existing texture to cut out another texure

Re: layer rgba

eldajanimahdi — Thu, 24 May 2018 14:51:52 GMT

Yes I understood how it works now , I wasn't using the opacity in the geometry channel 🙂 and using the overwrite operation with the mix parameter was very helpful ...thank you guys for your help

Re: layer rgba

eldajanimahdi — Thu, 24 May 2018 15:52:39 GMT

Finally the solution of Peter works when we have a separated alpha black and white and then we can put another texture to merge over without blending mode and it works for me....and Rachid solution works when we have an already png (transparency) alpha already cut...I think so

thanks guys