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<div class="moz-cite-prefix">Hi all<br>
<br>
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.<br>
<br>
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. <br>
<br>
<br>
Regards,<br>
Marco<br>
<br>
<br>
On 24.10.2013 12:03, A Huarte wrote:<br>
</div>
<blockquote
cite="mid:1382609036.60107.YahooMailNeo@web28902.mail.ir2.yahoo.com"
type="cite">
<div style="color:#000; background-color:#fff;
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<div style="font-family: 'times new roman', 'new york', times,
serif; background-color: transparent;"><span
style="background-color: transparent;">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. </span></div>
<div style="font-family: 'times new roman', 'new york', times,
serif; background-color: transparent;"><span
style="background-color: transparent;"><br clear="none">
</span></div>
<div><span></span></div>
<div style="font-family: 'times new roman', 'new york', times,
serif; background-color: transparent;"><span
style="background-color: transparent;">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.</span></div>
<div style="font-family: 'times new roman', 'new york', times,
serif; background-color: transparent;"><span
style="background-color: transparent;"><br>
</span></div>
<div style="font-family: 'times new roman', 'new york', times,
serif; background-color: transparent;"><br>
</div>
<div><br>
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<div dir="ltr">
<hr size="1"> <font face="Arial" size="2"> <b><span
style="font-weight:bold;">De:</span></b> kimaidou
<a class="moz-txt-link-rfc2396E" href="mailto:kimaidou@gmail.com"><kimaidou@gmail.com></a><br>
<b><span style="font-weight: bold;">Para:</span></b>
<a class="moz-txt-link-abbreviated" href="mailto:vincent.ml@oslandia.com">vincent.ml@oslandia.com</a> <br>
<b><span style="font-weight: bold;">CC:</span></b>
qgis-developer <a class="moz-txt-link-rfc2396E" href="mailto:qgis-developer@lists.osgeo.org"><qgis-developer@lists.osgeo.org></a>
<br>
<b><span style="font-weight: bold;">Enviado:</span></b>
Jueves 24 de octubre de 2013 11:59<br>
<b><span style="font-weight: bold;">Asunto:</span></b>
Re: [Qgis-developer] What about OpenGL renderding ?<br>
</font> </div>
<div class="y_msg_container"><br>
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<div class="yiv3479265157gmail_extra"><br
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<br clear="none">
<div class="yiv3479265157gmail_quote">2013/10/24
Vincent Picavet <span dir="ltr"><<a
moz-do-not-send="true" rel="nofollow"
shape="rect"
ymailto="mailto:vincent.ml@oslandia.com"
target="_blank"
href="mailto:vincent.ml@oslandia.com">vincent.ml@oslandia.com</a>></span><br
clear="none">
<blockquote class="yiv3479265157gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex;">Hello,<br
clear="none">
<br clear="none">
Le jeudi 24 octobre 2013 09:54:06, kimaidou
a écrit :<br clear="none">
[..]<br clear="none">
<div class="yiv3479265157im"><br
clear="none">
> In web mapping contexts, major
improvements are made in 2D vector
rendering<br clear="none">
> speed by using WebGl technology, such
as in upcoming OpenLayers 3. As a<br
clear="none">
> user point of view, improvement seems
huge compared to classical DOM or<br
clear="none">
> more advanced CANVAS renderer.<br
clear="none">
><br clear="none">
> What about using graphic card to help
improve rendering performance in QGIS<br
clear="none">
> ? Would this help a lot, or at the
contrary would this be a dead-end ?<br
clear="none">
<br clear="none">
</div>
We would probably begin with porting QGIS to
QT5, as OpenGL support has been<br
clear="none">
added to QT5 and improved in 5.1.<br
clear="none">
See for example :<br clear="none">
<a moz-do-not-send="true" rel="nofollow"
shape="rect" target="_blank"
href="http://qt-project.org/doc/qt-5.0/qtopengl/2dpainting.html">http://qt-project.org/doc/qt-5.0/qtopengl/2dpainting.html</a><br
clear="none">
<br clear="none">
Otherwise, reimplementing an pure OpenGL
rendering engine seems a big effort.<br
clear="none">
And we still would want to have a classic
renderer for non-accelerated<br clear="none">
hardware.<br clear="none">
</blockquote>
<div><br clear="none">
</div>
<div>Thanks for this ressource page about qt5<br
clear="none">
</div>
<div>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 ?
<div class="yiv3479265157yqt8046415445"
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<blockquote class="yiv3479265157gmail_quote"
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<div class="yiv3479265157yqt8046415445"
id="yiv3479265157yqtfd32304">
<br clear="none">
One really interesting thing is that it
would open the door for viewing 3D<br
clear="none">
objects in QGIS. As for now to be able to
see PostGIS 3D objects we had to<br
clear="none">
develop our own external 3D viewer
(horao). For that to happen we would need<br
clear="none">
real 3D geometry support in QGIS too.</div>
<br clear="none">
</blockquote>
<div><br clear="none">
</div>
<div><br clear="none">
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 !
<div class="yiv3479265157yqt8046415445"
id="yiv3479265157yqtfd97759"><br
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<br>
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<br>
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<pre wrap="">_______________________________________________
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<br>
<pre class="moz-signature" cols="72">--
Dr. Marco Hugentobler
Sourcepole - Linux & Open Source Solutions
Weberstrasse 5, CH-8004 Zürich, Switzerland
<a class="moz-txt-link-abbreviated" href="mailto:marco.hugentobler@sourcepole.ch">marco.hugentobler@sourcepole.ch</a> <a class="moz-txt-link-freetext" href="http://www.sourcepole.ch">http://www.sourcepole.ch</a>
Technical Advisor QGIS Project Steering Committee </pre>
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