Yet Another Material/Texture newbi question

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Yet Another Material/Texture newbi question

Postby Osmodivs » Sat Aug 27, 2011 10:24 pm

:oops:
Hello.
Sometimes I need to delete the background from an image, making it an alpha map.
I have been trying to add an alpha map to a mesh but with no success. I have UV the mesh and added the image
The settings are like this:
All of them have a glossy red (diffuse color) material. The bottom row has the alpha image, the first sphere has the M button (Multiply texture by color) turn ON. the second sphere has the M buttun turn OFF. The third sphere has the M button turn OFF but with the Luxrender Alpha Transparency box checked set to Difusse/Reflection alpha, and set the texture to Luxrender Type Image Map, Wrapping: Clamp.
The fourth sphere has the M button turn ON, with the same settingsas the third sphere.
The top row of spheres have the same settings as the bottom row of spheres, but the image has a white background.
I rendered the images with Blender and Yafaray and they come out as I want them to, I do not know what am I doing wrong here, Luxrender is so different from the rest that it needs a special way of handling materials and textures , I was looking for some info on the wiki but I coul not find anything, unless I missed some stuff wich I probably did, but hey, you are the experts.
Attachments
Blender_Yafaray.png
Left: Blender
Right: Yfaray
Alfa_Test.png
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Re: Yet Another Material/Texture newbi question

Postby Abel » Sun Aug 28, 2011 6:25 am

What you need is the mix material, using your alpha image as the mix amount and using the following two materials:
-one material that is just red, for the background
-one image that uses your texture for the diffuse channel

There is a tuturial here that explains the concepts; it may be a bit old but should still be usable:
http://www.luxrender.net/wiki/LuxBlend_ ... _materials
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Re: Yet Another Material/Texture newbi question

Postby Lord Crc » Sun Aug 28, 2011 8:17 am

Hmm hadn't thought about this use case. I think it may be possible to add this to the alpha transparency box, like a "decal" checkbox or something. I'll look into it.
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Re: Yet Another Material/Texture newbi question

Postby SATtva » Sun Aug 28, 2011 8:30 am

Could be related to this bug: http://www.luxrender.net/mantis/view.php?id=1113 I.e. the workaround is to set texture's V offset to 1.0.
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