[PD] [GEM-dev] Blending mode directly on objects, not pixes?

[Matteo Sisti Sette]

By the way, it seems to me that with this approach I can achieve:
- additive blending (by setting both sfactor and dfactor to GL_ONE)
- multiplicative blending (by setting for example sfactor=GL_ONE and 
dfactor=GL_SRC_COLOR)

but NOT for example subtraction or difference... or am I missing something?

Jack escribió:
> i forgot the patch.
> ++
> 
> Jack
> 
> 
> 
> Le dimanche 29 novembre 2009 à 15:41 +0100, Jack a écrit :
>> Le dimanche 29 novembre 2009 à 12:07 +0100, IOhannes m zmölnig a écrit :
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>>> Matteo Sisti Sette wrote:
>>>> Ohhhhhhh, ok!!!
>>>>
>>>> [env ( is the way the texture blends with the color of the survace (i.e.
>>>> the one set by [color])!!!
>>> ah right. that answer was late at night...
>>>
>>>> That's useless to my purpose: by blending mode I meant the way the
>>>> object (with its resulting color however it results from its color and
>>>> rexture) blends with its background
>>> yep. you should be able to control this on low level with
>>> [GEMglBlendFunc] and [GEMglAlphaFunc]
>> Sometimes the solutions are very simple, we just need a simple OpenGL
>> function :)
>> I have started to read the Red Book there is few month ago, i have to
>> finish it !
>> I have done this patch, is it correct to use different blend modes ?
>> ++
>>
>> Jack
>>
>>
>>>> At the end I think I'll use glsl: with a very small and trivial
>>>> modification to the "multitexture" example I've been able to
>>>> add/multiply/subtract two textures, so I'll use that to blend a
>>>> [framebuffer]ed image with another one as textures.
>>>>
>>> well, if you only want to change the blending between a surface and the
>>> background, then you should be able to do this without [gemframebuffer],
>>>
>>> but then you would have to re-implement the default fragment shader
>>> which is probably not worth it.
>>>
>>> i wonder why i miss something like ftransform() for fragment shaders.
>>>
>>> fgamr
>>> IOhannes
>>>
>>>
>>> mfasr
>>> IOhannes
>>>
>>>
>>>
>>>
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-- 
Matteo Sisti Sette
matteosistisette at gmail.com
http://www.matteosistisette.com