Movie with a mask?

[Scott Rossi]

Recently, Graham wrote:

>> Yes: set the alwaysbuffer of the player to true, then lay any masked image
>> over the player.
> 
> But what if the movie requires a different mask per frame? - imagine for
> example a windmill going round, so that the sails are in a different
> position in each frame, and you want the user to see the background behind
> the windmill except where the sails happen to be. Then AFAIKS you have to
> have a kind of movie mask - is this perhaps an alpha channel for the movie?
> I have tried to understand this in QT Pro but have got precisely nowhere.
> Information about how to do this sort of thing (including whether it's even
> possible) seems to me very hard to come by. My current solution is to avoid
> the problem by replacing the windmill with a spinning disk, but I would
> rather not.

If you don't have a lot of frames ('a lot' is a relative term) you could use
a series of PNG images which are masked as needed and swap them in sequence
in a button object.

Regards,

Scott Rossi
Creative Director

Tactile Media, Multimedia & Design
Email: scott at tactilemedia.com
Web: www.tactilemedia.com