[Marble-devel] New scanline access method

Torsten Rahn tackat at t-online.de
Sat Nov 7 10:59:55 CET 2009

Hi Carlos,

Interesting indeed (I wasn't aware of the detach).

Have you tried without changing the c-cast into a reinterprete cast?


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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