[PD-dev] [GEM] cvs

[chris clepper]

>On Fri, 9 May 2003 zmoelnig at iem.at wrote:
>>  unfortunately i am not sure, whether the only use of [pix_rgba] is for
>>  conversion into "native" colour-space.
>>  sometimes i really like having an alpha-channel....
>
>I was thinking the "native" colorspace is with alpha channel, but with
>yuv this is not the case, as I have heard.
>(In the film example pix_rgba was used to convert from RGB to RGBA,
>which I thought is a bit strange).

yes the buffer should be filled with R+G+B+A in order for the 
pix_objects to process the data.  GEM currently has no way to work 
with a 24bpp RGB buffer.  so it makes no sense to have the 
pix_film/video object deliver anything but 32bpp buffers.

>Yes the alpha channel is quite nice in several circumstances ..
>will this be lost on OSX when there is no pix_rgba ?

nope.  the native mac pixel format is ARGB and that's what the 
pix_film/video objects put in the buffers.  there's an ifdef for OSX 
that changes the ordering of the channels and GL_BGRA_EXT is the 
corresponding GL format.

cgc

>Guenter
>