I found no way to do that via transparency, but when i applied semitransparent texture to object, it is OK. But very hard way to render such an object for CPU

Nothing better.
If the object is plane, there is no problem, but "wave" object with d < 1 makes me trouble. Nothing helped me. I used manual for MTL http://paulbourke.net/dataformats/mtl/ but without success. Any suggestions?

For this time I Thank you. I will try.

Hello,
I have a problem with rendering, for example, transparent or semitransparent curtain. See my presentation set in the attachment.
Thanx for replies.