Single buffered drawing won't work with what he is describing, unless he repaints all of the brush strokes.  When a new video frame is drawn, it will overwrite everything.  This can be worked around by playing with the Z values though...set the video to draw behind the brush strokes and then make sure that you do Z writes for the brushes.  However, you won't be able to do alpha with this...

The best way to do this would be to either cache the brushes or renderer the brushes to another render target with alpha.  Then draw the video frame and draw the brush over top.  You could also hand render the brushes to a texture with alpha and then just draw the quad.  I don't know what the current set of GEM objects is though, so these 2 ideas might require creating some new objects.

Mark



Jack <jack@rybn.org>
Sent by: pd-list-bounces@iem.at

07/21/2008 05:04 PM

To
"Spencer Russell" <spencer.f.russell@gmail.com>
cc
pd-list@iem.at
Subject
Re: [PD] freehand drawing on video in GEM





As suggested by Chris, single buffer rendering is the good choice.  
Then send a bang from [metro 1] (for exemple) to [gemhead] to force  
the rendering (to your [gemhead] with the movie and to your [gemhead]  
for the 'painting').
++

Jack


Le 21 juil. 08 à 23:51, Spencer Russell a écrit :

> On Mon, Jul 21, 2008 at 5:28 PM, chris clepper  
> <cgclepper@gmail.com> wrote:
>> Single buffer rendering can be used for 'painting' using a geos as  
>> various
>> brush types.
>
> The difficulty though, is that I want to draw some parts in a freehand
> single-buffer style, but I want it to be mixed and layered with video
> that's drawn normally.
>
> thanks,
> spencer
>
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