[Scummvm-devel] MADE screen transitions (was: cost of palette changes)

[Max Horn]

Am 28.06.2010 um 23:55 schrieb Torbjörn Andersson:

> On 2010-06-28 22:48, Johannes Schickel wrote:
> 
>> All I know is that it is indeed expensive and thus should be only
>> done when needed. I think our MADE engine once was affected by too
>> many palette operations and thus bad performance.
> 
> (I didn't want to hi-jack the original discussion - at least not very 
> much - so I'm using a different subject for this one.)

[for reference, the original thread started Jan 31, 2010 ]


> Unfortunately, in the fixed version the screen transitions don't always 
> look as good as the original. There was a brief discussion about this 
> some time ago, but I don't think we ever reached any decision on what to do.

True. Though in mind that was partially because the question that was asked was "is there a way to detect whether a backend is fast?" for which the answer simply is "Not really, maybe you could write some benchmarking code, though" ;).

But maybe we can do something about "Can we do anything to improve those screen effects / reduce the slow downs and deal with it all?" :-).

In the original thread, "high CPU spikes (90%+) for 2-3 seconds" on desktop platforms for those effects were mentioned. That sounds pretty bad, but also somewhat surprising. Maybe the problem was/is that the SDL backend does not perform any screen update rate throttling, and so maybe it ended up over-updating the screen? Maybe our rendering pipeline (in the SDL backend, at least) is way to long and complicated and induces this major overhead? Also, did anybody test the effects on non-SDL ports?

Smooth 30FPS updates should be possible on any decent desktop machine produced in the last 10 years, including the palette update changes. 

And I just looked, the NDS port seems to have some native 8bit support, so maybe it is not so bad there at all!

Bye,
Max