[QGIS-Developer] Some initial OpenCL feedback

[Andreas Neumann]

Hi Alessandro, 

I just tested if the hardware acceleration (OpenCL) helps in the live
hillshade renderer. 

The good news is that it works stable so far and substantially improves
rendering time of the live hillshade renderer. My notebook on my
workplace is rather slow. Without hardware acceleration it renders the
hillshade in approx 8 seconds (large window on two screens). With OpenCL
acceleration set to on, it renders in about 1 second or even less. I
assume quite some time is also spent on reading the file. This with
resampling on (average for zooming out and bilinear for zooming in
beyond native resolution). 

Hardware is an Intel HD Graphics 4600. The CPU is also listed as
supported. 

Visually, with or without HW accelation on, there still are some
rectangular artefacts in both versions. 

Tested on Windows. 

-------------- 

One more thing: on my machine there is no restart of QGIS necessary for
the changes (HW acceleration on of off) to be applied. This is contrary
to the statement in the settings dialogue, which says, that a restart of
QGIS is necessary. 

--------------- 

Thanks a lot for your work! 

Andreas
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