[PD] gem motion blur & alpha

[cyrille henry]

hello,

i suggest doing the feedback in a black FB, and then applying this texture thanks to a custom shader in order to program the blending function you need.

cheers
c


Le 28/08/2017 à 00:56, andre rc a écrit :
> Thank you for the patch Cyrille. It's a very nice solution.
> The only disadvantage is that it makes the background image feedback dependent.
> My goal is to isolate the feedback from other geos & image/videos.
> So, I was thinking that in order to keep the blur I have to keep the gemframebuffer RGB format and add transparency after it.
> I just realized that [alpha] has several blending functions, some of them turn the whole framebuffer transparent.
> This is fine but now the geo and blur are also affected (see attached).
> I don't know if it is possible to add other type of blending after the framebuffer, maybe sending it to another gemframebuffer and changing the background color (black) to alpha?
> I saw that pix_alpha achieve this but I don't know how to use it only with the framebuffer image. Any suggestion is welcomed :)
> 
> regards,
> andre
> 
> 
> 
> On 27 August 2017 at 11:48, cyrille henry <ch at chnry.net <mailto:ch at chnry.net>> wrote:
> 
>     hello
> 
>     Le 27/08/2017 à 03:05, andre rc a écrit :
> 
>         Hello,
> 
>         I'm trying to apply motion blur only to one geo with gemframebuffer.
>         It works fine until I add a background image: when I switch the gemframebuffer format from RGB to RGBA the amount of motion blur decrease considerably.
> 
>     yes, since the feedback image became more and more transparent...
> 
> 
> 
>         Is there a way to get the same amount of motion blur (long tail) with alpha on?
> 
>     replace [color 1 1 1 0.95] with [color 0.95 0.95 0.95 1]
> 
>     but that's not what you want since it will fade to black and not to transparent.
> 
> 
>     an other solution would be : you can alter the color of the feedback image by drawing a bit of the BG on top of it.
> 
>     attachment example.
> 
>     cheers
>     c
> 
>         Attached example.
> 
>         thanks & regards,
>         andre
> 
> 
> 
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