How to get a not tiled texture based on image alpha?

[Micha]

Hi,

I have a PNG with transparency and ask me, how can I get the area around the texture also transparent? Where I can define the transparency outside the textured area? Maybe an option is missing.

-Micha

[richard_aubin]

Use the same texture in the opacity texture/bitmap slot. Make the background black, and the foreground white (your logo).

[Micha]

Thank you, that's the standard way without "Diffuse Texture Alpha".

So, if there is no direct way than I want to formulate my question as a wish to the team: please allow to use the opacity slider for the area around the map. At the moment the slider is inactive and why not use them?

[nikolay.bakalov]

Will not decal work for you ?

Is this what you're after (on the right side):

[Micha]

General decals are nice, but some times I have trouble to use decals, for example if I use metal within materials. Than the decal doesn't look good since it can't be limited to be plastic.

[nikolay.bakalov]

What I posted is not a decal, so I'm asking if that is what you ate after

[Micha]

Oh, yes, the right side shows what I want - alpha from PNG and anything around invisible.

[nikolay.bakalov]

In this case you have to copy the diffuse texture to the opacity slot and set its "Default Color" to black. This property is the texture/color outside of the UV space
stamp.zip

[Micha]

Thank you, your example file works fine. I tried an own texture and it doesn't work. Is it needed that the background of the texture is black?

[nikolay.bakalov]

Hi,

ideally - yes, your background is white and it has a red, green and blue values different than 0. It is better to have a BW image for the opacity channel

[Micha]

It would be great if the nice simple option "Diffuse Texture Alpha" could work with any not tiled PNG. Couldn't the opacity slider be enabled as opacity default color if "Diffuse Texture Alpha" is enabled. So, no extra UI element would be needed and user would get all freedome for a quick and simple setup.

[nikolay.bakalov]

Well, itis simpler than that. You only need the default colorof the diffuse slot to be AColor(0,0,0,0). However the Asset Editor is not a big friend to the alpha color channel. This is why I suggest using a special opacity texture. In the currently released versions there is no other way. I'm making some changes in the backend so it would be possible in the near future.

[nikolay.bakalov]

Guys,

we just rolled out a new update,
I made some changes there to simplify this workflow. It is not perfect, but kind of OK for the limited time frame I had

so.. just make your material as usual, put a texture in the diffuse slot, check the "diffuse texture alpha" checkbox for the opacity
and then run this code in the python editor:

import rhVRay as vray

vray.Scene.BeginChange()
vray.Scene["/Generic/VRay Mtl/Bitmap"].nouvw_color_color=[0,0,0,0]
vray.Scene.EndChange()

where "/Generic/VRay Mtl/Bitmap" is the url path to your diffuse texture for the given material. You can find it by exporting a .vrmat file and taking the <your material>'s diffuse name
here is the result


I hope we can be able to expand the color picker to use alpha channels, in which case the whole scripting thing won't be necessary