i have understood all your points, thanks iOhannes,

now: if i put an image from a pix_film directly to the buffer_write then i can read fine from the buffer,

but if i put the pix_film across a texture and then a snap, (see patch) the result of the buffer is black again,

maybe because the snap it's not in the good place??? or because x,y of snap are bad??

thanks,

On 6/26/06, IOhannes m zmoelnig <zmoelnig@iem.at > wrote:

Carles Sora wrote:
> hi list,
> I'm new here,
>
> I'm trying to put into pix_buffer a screenshot with pix_snab but it
> doesn't work well,
> the pix_buffer_read draws a black image,
> i thing that could be by the order of render, but i'm not sure
> in the attach file you will see what I say.

several things:
1) you need something rendered into the buffer before you can make a
meaningful snapshot (if you make a snapshot of an empty gemwin, then the
image is likely to be black)
2) [pix_buffer_write] will only write the image into the buffer in the
render cycle immediately after the 2nd inlet gets set. (this is kind a
means for saving CPU power.) so each time you want to write something
into the buffer, you will have to bang the index-number you want to
write too (connect the [snap( with a [bang( to the index)
3) [pix_buffer_read] will only update the image when it is told to do
so: e.g by (re)setting the index; again, this caching is for performance
reasons (and probably sometimes annoying); if you want to force the
buffer to be read each cycle, just send bang the index each render cycle.

hope this helps

,fg,asdr
IOhannes