Only some objects invisible behind an invisible plane or box?

I’m doing some kind of animation. There (x,z) text rotates around the y-axis in the picture and the hole thing rotates in the middle of z-axis. The problem is a part where the text should disappear:
There is two lines. In between them the text should be invisible but everything else should be visible. How could I possibly do this with blender?

(I hope I created this tread in a right place)

z-order fighting? my first guess would be to move the text back (y-axis?).

z-order fighting???

Well if I move the text back at that part it is still visible.

As you can see there is a word “was”. I would like to get the “w” and a part of “a” and “s” be invisible in that picture but when the text moves around only the part of text that is between those lines should be invisible. It wont help much if I just hide and reveal character by character when there is so long character that is visible at the same time in both sides (in the visible and invisible side).

So I think there should be some kind of (totally invisible) glass. Behind it every object expect the text should be shown normally. But how to do it?

I did quick sketch from the idea:
Light blue is text.

A .blend will say it better than i can:
http://smokin.homeip.net/uploads/junk/roundtext.blend
Notice that the alpha texture is mapped to the empty object so it won’t spin with the text.

(First of all, how did you get the text to around? edited: Found it: “text on curve”)

(How could I find the alpha texture? Edit: Found it on text but I dont get it yet…) How could I see the “alpha.mas”?

(Damn it. There is lot to learn…)

But thanks! That sketch helps a lot.

I packed the alpha mask into the .blend so if you want to see it open a UV Image Editor window and select the image from the dropdown list. From there you can see it, save it or load a different one - I would suggest making a different one because the one in the file was made in blender’s image editor so I didn’t spend alot of time on it (you would probably want a hard transition from black to white rather than the fuzzy edge I made).
Then the image was selected as a texture for the text’s material. The texture is mapped to the alpha channel (you have to turn the material alpha to 0 so the texture alpha takes over). The texture location is mapped to an empty (that’s in the middle of the text) as you see in the texture mapping panel. I thought that the texture size could be 1,1,1 (x,y,z) but I had to scale that up because the text itsef was scaled down (play with the mapping scale to see what I mean).
Anyway, hope that helps… and yes, there’s alot to learn. Keep at it, you’ll get it.

Now it seems to work all right. Thank you. :smiley: