Are all Blend combinations equal in performance costs?

Unity Engine
1

For example does using

Blend Zero SrcColor

instead of

Blend SrcAlpha OneMinusSrcAlpha

have a difference in performance , or are all combinations of Blending equal?

2

How much depends on the hardware, but different factors definitely change the per-fragment cost of blending.

3

I did some testing on an iPhone 3GS. I don’t think that this is an area where you’ll ever notice performance differences.

4

Ok thanks

Im going to use Blend Zero SrcColor then . Its for a DMD mask and with android not having compressed alpha texture support I can use a etc4 black and white texture with this Blend combination to achieve the same visual result as if it were an alpha overlay.

5

It’s important to keep in mind that the 3GS represents a very specific type of device: a tiled deferred renderer with relatively few pixels to fill. I would be surprised if there weren’t more traditional hardware that saw a speed boost from not having to read from the frame buffer.

6

I wouldn’t be surprised because once blending is enabled in traditional fixed-function hardware, the data might be (computed and) transferred in any case, even if it is multiplied with 0 in the blend equation.

7

I blended a ton of meshes until the framerate plummetted. Many pixels more than what the screen represents had to be blended. No rendering could be deferred because nothing was opaque.

No difference in modes.