Hi all
Qt already has an open gl based paint device ( QGLPixelBuffer ), so the
effect of hardware acceleration can be tested just by replacing the
QImage with a pixel buffer. I did this years ago and ( can't remember
the Qt version ), the rendering with QGLPixelBuffer was slower on my
computer compared to QImage. Additionally, the graphical quality was lower.
The reason might be that transfer of data to the GPU is slow, but
rendering is fast. So it would probably need a non-QPainter based
approach to store the data at the GPU and use repeatedly then. Afaik
Hugo Mercier has experience using a non-QPainter based approach (as used
in the 3D example city of Lyon). However, such an approach would require
very fundamental changes in lots of places in the core library.
Regards,
Marco
On 24.10.2013 12:03, A Huarte wrote:
There is also a more ambitious option, detach in QGIS the render of
the objects of the painting technology ( Currently Qt+QPainter ) using
interfaces as Ogre, Irrlicht or OSG does.
Then could be implemented several 2D/3D-CPU/GPU renderers ( Qt4-5,
OpenGL, OpenGL ES, Ogre, OSG ...) being the rendering mode (2D/3D or
CPU/GPU) changeable from a single application option.
------------------------------------------------------------------------
*De:* kimaidou <[email protected]>
*Para:* [email protected]
*CC:* qgis-developer <[email protected]>
*Enviado:* Jueves 24 de octubre de 2013 11:59
*Asunto:* Re: [Qgis-developer] What about OpenGL renderding ?
2013/10/24 Vincent Picavet <[email protected]
<mailto:[email protected]>>
Hello,
Le jeudi 24 octobre 2013 09:54:06, kimaidou a écrit :
[..]
> In web mapping contexts, major improvements are made in 2D
vector rendering
> speed by using WebGl technology, such as in upcoming
OpenLayers 3. As a
> user point of view, improvement seems huge compared to
classical DOM or
> more advanced CANVAS renderer.
>
> What about using graphic card to help improve rendering
performance in QGIS
> ? Would this help a lot, or at the contrary would this be a
dead-end ?
We would probably begin with porting QGIS to QT5, as OpenGL
support has been
added to QT5 and improved in 5.1.
See for example :
http://qt-project.org/doc/qt-5.0/qtopengl/2dpainting.html
Otherwise, reimplementing an pure OpenGL rendering engine
seems a big effort.
And we still would want to have a classic renderer for
non-accelerated
hardware.
Thanks for this ressource page about qt5
I agree with you : why reinvent the wheel if QT5 proposes needed
and mature tools. I just hope porting QGIS to Qt5 won't be so hard
that it would postpone it to 3.0 though :) Have any discussions
begun on this topic among QGIS devs ?
One really interesting thing is that it would open the door
for viewing 3D
objects in QGIS. As for now to be able to see PostGIS 3D
objects we had to
develop our own external 3D viewer (horao). For that to happen
we would need
real 3D geometry support in QGIS too.
Exactly, I have seen your video for Lyon town project, this is
great ! I can only imagine what a speed improvement it would bring
for "simple" 2D painting !
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--
Dr. Marco Hugentobler
Sourcepole - Linux & Open Source Solutions
Weberstrasse 5, CH-8004 Zürich, Switzerland
[email protected] http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee
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