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

Max Neupert abonnements at revolwear.com
Tue Dec 25 19:04:05 CET 2007

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.


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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