From: Greg Ercolano <erco@(email surpressed)>
Subject: [Q+A] submit-mayatile.pl in 102.42a5 (and older) won't render out
   Date: Thu, 27 Apr 2006 14:30:47 -0400

> When I render with the submit-mayatile.pl script, the output images
> have the alpha channel flattened out to black. Is there a way to get
> it to output images with the alpha channel preserved?

    Yes; a small modification is needed to the submit-mayatile.pl script
    to support alpha channels. (thanks Sean P. @ Turner)

    In the submit-mayatile.pl script, the 'montage' command currently
    looks like this:

----------------------------------------------------------------------------

    my $command = "montage -mode concatenate ".
                      "-background \"#000000\" ".
                      "-tile $$in{XTiles}x$$in{YTiles} ";

----------------------------------------------------------------------------

    It's the '-background #000000' line that's flattening out the alpha channel.

    To preserve the alpha channel, change this line:

                      "-background \"#000000\" ".

    ..to instead read:

                      "-background none ".


    Now when the scene is rendered, the resulting output image will have
    the alpha channels preserved.