[PD] GEM Pix video transparency

Roman Haefeli reduzierer at yahoo.de
Sun Feb 12 16:07:50 CET 2006

hi jonathan

i attached an expample, with that you can blend (change transparency) 
between 2 images. just replace [pix_image] with [pix_video] or with 
[pix_movie] (or whatever generates pixes).
i think the [alpha] adds a fourth channel to the pix-stream. to change the 
transparency (alpha-channel) you need the obj[colorRGB]. i think you could 
do the same with [pix_color], but [colorRGB] computes on the gpu, wich is 
much faster, if you enabled hardware acceleration (opengl). then you need 
[pix_texture] to map the pix-data onto a geo as a texture. also here you 
could achieve the same with [pix_draw] instead of using 
[pix_texure]-[rectangle], but the latter is much cheaper.


"Jonathan Goodwin" <jonathan at jgoodwin.co.uk> wrote:

> I'm trying to figure out the best way to adjust the transparency of
> pix_video, so that I can overlay a live webcam feed over other videos.
> What would people recommend? I've had a little play with the alpha object,
> but I'm having a bit of trouble understanding the whole threshold 
> arguments
> thing?!
> Jonathan
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