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

[Bernhard Beschow]

> On 2010-12-13 20:27:26, Torsten Rahn wrote:
> > /trunk/KDE/kdeedu/marble/src/lib/FastMercatorTextureMapper.cpp, line 76
> > <http://svn.reviewboard.kde.org/r/6109/diff/1/?file=42509#file42509line76>
> >
> >     waht happens if numTilesX or -Y or radius becomes 0 ? :)

That's not supposed to happen. :) I'll Q_ASSERT it.


> On 2010-12-13 20:27:26, Torsten Rahn wrote:
> > /trunk/KDE/kdeedu/marble/src/lib/FastMercatorTextureMapper.h, line 20
> > <http://svn.reviewboard.kde.org/r/6109/diff/1/?file=42508#file42508line20>
> >
> >     "Fast" doesn't really provide an idea how this works.

Right. IMO ScalingTextureMapper would be a better name. Last but not least it can also be applied in the same way to the Equirectangular projection.


- Bernhard


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On 2010-12-13 23:46:02, Bernhard Beschow wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://svn.reviewboard.kde.org/r/6109/
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> 
> (Updated 2010-12-13 23:46:02)
> 
> 
> 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 1205882 
>   /trunk/KDE/kdeedu/marble/src/lib/AbstractScanlineTextureMapper.cpp 1205882 
>   /trunk/KDE/kdeedu/marble/src/lib/CMakeLists.txt 1205882 
>   /trunk/KDE/kdeedu/marble/src/lib/FastMercatorTextureMapper.h PRE-CREATION 
>   /trunk/KDE/kdeedu/marble/src/lib/FastMercatorTextureMapper.cpp PRE-CREATION 
>   /trunk/KDE/kdeedu/marble/src/lib/TextureLayer.cpp 1205882 
> 
> 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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