how to export an openGL scene with alpha channel?

    Feb 07 2008 | 11:33 pm
    hello list !!
    i have a problem: I have a openGL patch wich render a bunch of
    particles; I am exporting this openGL
    scene in "animation" .mov format, and what i want to do is to export
    the background with the alpha channel.
    I know the "animation" compression can have the alpha channel, but
    from the openGL renderer i have no clue
    of how to set the alpha value of the background to 100%. The
    erase_color have the argb, but when i put rgb
    values to 0 end the alpha value to 1 the background is black and the
    exported .mov file doesnt seems to have
    any alpha channel.
    any hint??
    to render and export my patch I m using the (fantastic!!) render node
    by Randy Jones -
    but the process would be the same also without it..
    live media and vjing
    Mattia Casalegno