[PD] GEM : GLSL Mixer - working 2 channel video mixer example

vade doktorp at mac.com
Tue Dec 25 20:53:34 CET 2007

Hm. Interesting. GEM does not have a drop frame system? Im not sure  
about the scheduler differences between PD and Max/Jitter, but most  
Jitter events are in a different queue and have a drop frame handling  
method built in to each object, and when drawing with openGL one  
should use a 'qmetro', or a queue limited metro -  to avoid such a  
case. Im speaking a bit out of my realm of expertise but I dont really  
think a Patcher should be able to do that, if it did indeed lock up  
your system.

What is the proper way of handing this in PD/GEM? Sorry for causing a  
crash. I saw your PD Jitter patch, but frankly I think some drop frame  
system should be built into GEM to handle this automatically.

Anyway, what kind of powerbook? It may not have the required hardware  
support for the shader, which might be why you are only getting 10fps,  
via software fallback?

On Dec 25, 2007, at 1:04 PM, Max Neupert wrote:

> very interesting, but also a good example on how to lock the computer
> completely with gem - at least my old powerbook. i had to hard reset
> because complete unresponsiveness. with [frame 10( it runs nicely
> though. see my last post on how to avoid the lock-up.
> max
> Am 24.12.2007 um 21:35 schrieb vade:
>> Yes, very efficient, and also give you LOTS of flexibility . the
>> regular GL_BLEND_MODES do not offer that many variations (not many  
>> are
>> useful for video). Want to make a GPU powered chroma key - shader.
>> Want to make feedback but have FSAA on, probably shader :)
>> etc etc. Want to make 4 way mixer? shader! See where I am going
>> here? :)
>> On Dec 24, 2007, at 3:29 PM, Hans-Christoph Steiner wrote:
>>> Nice, works for me.  Is the idea that shaders are a efficient way of
>>> mixing video?
>>> .hc
>>> On Dec 24, 2007, at 12:04 PM, vade wrote:
>>>> Hello
>>>> Here is a 2 channel mixer using overlay blend mode with GLSL. This
>>>> works, is decently fast and gives me the expected result.
>>>> If you want more blend modes, feel free to grab them from http://
>>>> 001.vade.info
>>>> (or elsewhere, most are trivial to figure out)- the glsl shaders
>>>> for the mixers use the same subroutine layout in the glsl, so it is
>>>> trivial to swap. I did not include them out of sheer laziness.
>>>> Caveats with PD 0.4.03 Extended nightly from Dec 24th (Mac OS X
>>>> 10.5.1, QT 7.3, Intel):
>>>> - had to edit the GLSL program to fix multitexture coordinate
>>>> issue. Only can use the texture dims from the zeroths texture unit.
>>>> - could not get sampler2DRect working at all - only had a single
>>>> texel mapped it seemed.
>>>> - had weird issue where I would sometimes have to close the gemwin
>>>> (0, destroy) and then re create it to see the textures assigned to
>>>> texture units.
>>>> 	this happened most often after closing and re-opening the patch.
>>>> Please see the included question(s) within the PD patch concerning
>>>> using framebuffer to grab the output of the rendered shader and
>>>> send it to yet another shader. Ive included an exposure shader in
>>>> an attempt to make a chain of GLSL effects. I however could not get
>>>> gemframebuffer to output any usable texture after using  
>>>> glslprogram.
>>>> Thanks, hope this is helpful to those out there
>>>> FUDDLE DUDDLE !@#!@#!@#()*!@#(*@#
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