[Marble-devel] Re: Review Request: introduce optimized code path for Mercator projection

[Bernhard Beschow]

> On 2010-12-13 22:03:59, Torsten Rahn wrote:
> > /trunk/KDE/kdeedu/marble/src/lib/FastMercatorTextureMapper.cpp, line 81
> > <http://svn.reviewboard.kde.org/r/6109/diff/1/?file=42509#file42509line81>
> >
> >     Have you tried using QRectF here? And maybe calculating xLeft, yTop and xRight/yBottom as floats to reduce artifacts?
> 
> Bernhard Beschow wrote:
>     No, but it should be easy to do. :)
> 
> Bernhard Beschow wrote:
>     I didn't notice any difference. Since it doesn't seem to affect speed, I changed it to QRectF.
> 
> Torsten Rahn wrote:
>     Have you used QPointF and floats for xLeft, etc. as well (together with QRectF)?

Yes.


- Bernhard


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On 2010-12-22 22:33:36, Bernhard Beschow wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> http://svn.reviewboard.kde.org/r/6109/
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> 
> (Updated 2010-12-22 22:33:36)
> 
> 
> Review request for marble.
> 
> 
> Summary
> -------
> 
> This patch introduces an optimized code path for the case that both the tile projection and the map projection are of type Mercator. In this very common case, the tiles can be scaled rather than reprojected, promising a significant speedup. Moreover, it seems to avoid crashes in high zoom levels on the N900.
> 
> 
> Diffs
> -----
> 
>   /trunk/KDE/kdeedu/marble/src/lib/AbstractScanlineTextureMapper.h 1208706 
>   /trunk/KDE/kdeedu/marble/src/lib/AbstractScanlineTextureMapper.cpp 1208706 
>   /trunk/KDE/kdeedu/marble/src/lib/CMakeLists.txt 1208706 
>   /trunk/KDE/kdeedu/marble/src/lib/TextureLayer.cpp 1208706 
>   /trunk/KDE/kdeedu/marble/src/lib/TileScalingTextureMapper.h PRE-CREATION 
>   /trunk/KDE/kdeedu/marble/src/lib/TileScalingTextureMapper.cpp PRE-CREATION 
> 
> Diff: http://svn.reviewboard.kde.org/r/6109/diff
> 
> 
> Testing
> -------
> 
> I have measured speedups of up to 2.7 on my system. This seems to depend on the QImage::Format, so format conversion should be avoided in a future version if possible.
> The image quality is roughly of outline quality when a discrete zoom level isn't hit.
> 
> I get crashes on my Netbook, but not on my other machine. The error message is: "QPaintDevice: Cannot destroy paint device that is being painted". I've got no idea what's going on here. Please help.
> 
> 
> Thanks,
> 
> Bernhard
> 
>

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