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

Hans-Christoph Steiner hans at eds.org
Mon Dec 24 21:29:02 CET 2007

Nice, works for me.  Is the idea that shaders are a efficient way of  
mixing video?


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 !@#!@#!@#()*!@#(*@#
> :)
> <GEM_glsl_2_channel_mixer.zip>
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Using ReBirth is like trying to play an 808 with a long stick.    - 
David Zicarelli

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