Comme=
nt # 54
on bug 11078=
1
from =
Richard Thier
> The GPU has a scaler that can scale=
a smaller image to the native timing. Many > LCD monitors also have a =
scaler built in to provide the same functionality.
I see, but still I see a big performance rise when I change the resolution
smaller and let this scaler do its work in the last phase.
I have no idea if there is a real speed difference between this two:
- having 640x480 on a 4:3 aspect screen without a scaler
- Having hardware pixels of 1024x768, but using the scaler in the end as
640x480 software.
- Z tests run for smaller amount of pixels
- Stencil and Z buffers are smaller just like the backbuffer
- etc.
Memory usage on the GPU should be still smaller, pixel shaders still run ra=
rer
times, post processing things still run on smaller amount of pixels etc... =
The
only reason it can be slower if for some reason the scaler circuit would be=
so
slow while doing its job that it cannot keep its FPS, but I think this is a
highly specialized hardware not doing anything else so I hoped it is just
"fast" and even if there is some loss I guess it is barely measur=
able - but
tell me if I am wrong as that would be new to me if this has a really
measurable overhead.
In any ways I think it is better to use a same aspect ratio, but smaller
resolution than using the biggest possible native size. Actually on my mach=
ine
I get faster frame rate even if I run a game in 640x480 window on the top l=
eft
corner the same way as if I turn the screen into 640x480 itself and even th=
en I
barely see a difference despite this case I feel there should be some overh=
ead
against using directly a video mode for that..