[PD] GEM - alpha blending of images over movies

Item State itemstatechanged at yahoo.de
Fri Feb 16 22:10:53 CET 2007

ok, thanks for clarification.

but what about pix_movie, it seems to be in another
domain than pix_image because i cannot apply the
processes to it that i can apply to pix_image. also
pix_image "needs" either pix_draw or pix_texture ->
pix_rectangle, while pix_movie goes directly into
pix_rectangle without an intermitting pix_texture, and
it cannot be plugged into pix_draw ...?

ciao, -sciss-

--- Roman Haefeli <reduzierer at yahoo.de> wrote:

> On Sat, 2007-02-17 at 06:32 +1100, Item State wrote:
> > unfortunately i have the same problem with your
> patch
> > (psychedelic colours). the [colorRGB] is pretty
> cool,
> > it does exactly what i want, but this only works
> here
> > with [pix_texture] but have no effect when using
> > [pix_draw] instead...
> i hope i can clarify this a bit in my own (maybe not
> too correct) words.
> there are actually two different domains in Gem:
> opengl and 'pix'es. all
> opengl-based stuff is renderend on the gpu (graphic
> card's cpu), whereas
> all pixel-based objects are calculated on the cpu.
> playing and
> processing videos and pictures happens in the
> pix-domain (afaik, all
> pix_*-objects work in that domain). pix_texture is
> used to convert an
> image (from a picture or a video) to a texture, that
> can be applied to a
> vertex . that means the picture is then in the
> opengl-domain and cannot
> be processed with pix_*-objects anymore. so there
> are actually two (or
> more?) ways  of alpha-blending a picture:
> 1) do everything in the pix-domain and use
> [pix_alpha] (i'm not quite
> sure anymore about that)
> 2) give it to the opengl-domain using [pix_texture]
> and use the fourth
> (alpha-channel-)inlet of [colorRGB].
> the latter approach has the advantage, that
> everything is rendered on
> gpu, which saves you a lot of cpu-power. whenever
> you can, i would do
> stuff in the opengl-domain (unless you don't have
> any 3d-acceleration
> enabled). 
> i hope i didn't tell you something completely wrong
> (please someone
> correct me, if i did)
> roman   
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