[Marble-devel] New scanline access method

Torsten Rahn tackat at t-online.de
Sat Nov 7 11:28:45 CET 2009


I've tried it without the reinterprete cast and there isn't much of a 
difference. I consider making the chance nevertheless as it avoids the detach 

BTW: A general performance tipp:

If your fps are this low then I suggest that you go into the 

Settings->Configure Marble-> Map Quality 

And then you change the Graphics System to "Raster" and restart Marble. This 
will often enough result in performance improvements if your framerates seem 
very low.


Am Samstag 07 November 2009 08:08:58 schrieb Carlos Licea:
> List,
> 	Reading through the planet I found this post:
> 	http://zecke.blogspot.com/2009/11/collecting-hints-to-increase.html
> 	When I checked the repository I found:
> 	http://gitorious.org/qt-performance/qt-performance/blobs/master/performanc
> e- guide/qimage.xml
> 	I immediately remembered that we use QImage::scanLine method in the
>  ScanLine approach and sat down to try the new approach.
> 	Here you have the patch.
> 	Short story: doesn't seem to work.
> 	Long story: I didn't do any very deep analysis just ran marble with the
> option --timedemo and here are the results (they are not averages of
>  multiple runs, I just ran them a couple of times and wrote the value once
>  when I saw that I didn't have any gains):
> 				Old approach			New approach
> Spherical			45414ms"=4.40383 fps"	58491ms"=3.41933 fps"
> Equirectangular	58673ms"=3.40872 fps"	61583ms"=3.24765 fps"
> Mercator			66459ms"=3.00937 fps" 	71495ms"=2.7974 fps"
> 	It's really thrilling that we not only we are not improving, but that we
>  are having even worse performance.
> Carlos
> PS: I couldn't CC the author of the post. I wasn't able to find his email
> address (not that I really, really tried).

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