vade escribió:
You can do arbitrary blend modes in PD with GLSL as you suspect. take a
look at http://001.vade.info/?page_id=20 which has shaders for video
mixers (a through a+b to b blending, not just a+b) with most photoshop
blend modes.
Hi,
I just had a very quick look, but it seems to me that your mixers use 2
textures, very much like the "multi texture" example I mentioned.
To use them, you need two textures and you obtain the blended picture.
I was looking for a way to replace the blend function, the very same
function whose parameters you can modify using glBlendFunc and
glBlendEquation.
In order to use a two-texture mixer for my purpose (which is to change
how the object blends with the background), I would need to repatch
everything so that I snap the scene into a texture before blending. In
my case it would be quite a radical repatching.
However, after a little bit of googling, it seems that what I would like
to do is simply impossible, isn't it? If I understand correctly, with
glsl one can "only" modify the vertex and fragment transformations,
while the blending phase cannot be modified. Is it correct?
If so, is there a way I could do "difference" blending, that is the
absolute value of the difference between source and destination colors?
I have already done additive and multiplicative blending with
glBlendFunc alone, and I should be able to do subtractive with
glBlendEquation... can anybody suggest a way to get the absolute value?
Thanks
m.
--
Matteo Sisti Sette
matteosistise...@gmail.com
http://www.matteosistisette.com
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