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Speeding up by Alpha-premultiplying RGB?

PostPosted: Dec 15, 2006 @ 11:11pm
by Bunkai

PostPosted: Dec 19, 2006 @ 9:05am
by Johan

Thanks for the tip! I will look into to see if we can integrate this in some nice way for the next release.


PostPosted: Dec 20, 2006 @ 10:07am
by Bunkai

I assume, this could speed up alpha blitting by 30% maybe, and thats not bad at all. All it requires is not to multiply RGB by Alpha value on render time, because alpha premultiplied RGB is already delivered in imported image.

To see that this is a standard and frequently used approach, Google proves that: ... iplication

With regards,

Re: Speeding up by Alpha-premultiplying RGB?

PostPosted: Jan 4, 2011 @ 3:22am
by InexorableTash
I've been away from GapiDraw for a few years; I just updated my hobby project from 3.7 to 4.2, which went smoothly (unfortunately my architecture propagated the Create*Surfaces calls down the hierarchy so I needed to change many signatures). But back on topic:

Did anything ever become of this request? I have some textures with premultiplied alpha baked in and have been living with the black fringes; I don't see anything in the .H files that would indicate that this went in.

(You can see the effect in at around 3:45 - obviously, this is only a hobby project and would never be released.)

Re: Speeding up by Alpha-premultiplying RGB?

PostPosted: Jan 17, 2011 @ 9:50am
by Johan
Hello there,

No, this feature never made it to GapiDraw.