Is it possible to make an alpha texture (I don't mean transparent)

Hi, I am wondering if it is possible to make an alpha texture. When I say an alpha texture I don’t just mean turn on transparency, I mean that it renders out as alpha but blocks out any objects behind it making them alpha as well even if they are not.

For instance you have a scene which is a room of a house. It has a cube in the middle which as an alpha texture. When rendered the scene as an alpha section where the cube was.

Is this possible? Any suggestions to what settings the texture should have? (internal render engine, not cycles)

“When rendered the scene as an alpha section where the cube was.”
im sorry but that do you mean? you want the cube to have an alpha grid?


or you want the cube to have this “grid” as a solid texture?
kinda like the un-textured block in minecraft?

Also not entirely sure what you mean…

If you’re using Cycles, try this:
a) Check Film > Transparent in the Render properties tab.
b) Give the cube a Holdout shader.

The Holdout will basically create a hole where the cube was and the transparent background will make that hole an alpha area. Save to a file format that actually support an alpha channel, like e. g. png.

For Blender Internal a similar solution would be:
a) Set Alpha to Transparent in the Render > Shading properties tab.
b) In the material settings for the cube check Transparency, select Mask and set Alpha to 0.

If that’s not what you meant, show us a picture of the desired result!

I guess what I’m suggesting is similar to chroma keying. If I made a cube in the middle of a scene green. Rendered it out and went into something like after effects and keyed out the green I would have an alpha section where the cube originally was. I guess chroma keying is actually one solution for this but I was wondering if there was a way you could do it in one step in blender alone.

So it would be like the minecraft picture above but when rendered the un-textured block would only show the alpha grid like above meaning if taken into something like after effects you could put an image behind it and see it in only the cut out bit.

I hope I’ve managed to explain it a bit better.

This has solved it, thank you!