[QGIS-Developer] PYQGIS - OpenGL in QgsPluginLayer

[Eric Younkin - NOAA Federal]

Hi Martin,

Thanks for the quick reply.  This is for NOAA nautical chart symbology,
following the s57/s52 spec.  You can see the symbology in the online viewer
here <https://www.nauticalcharts.noaa.gov/ENCOnline/enconline.html>.  It is
basically a very complex spec that we generated for display in a wxPython
widget a long time ago using GDAL 1.x commands.  S57 is already an existing
OGR driver, although I do not know what exactly that driver does.  I do
know that it does not somehow generate the symbology of the data for you to
then render.

The vector data would be a combination of area/line/point features, and I
don't think it would be a fit for the Mesh layer.

We'd like to make this symbology available in QGIS, so that users can drag
in a s57 file and view the chart.  You can use one of our WMS services, but
having the file support would be useful.  Ideally in a plugin layer, so
that I can also use it in our other apps that use PYQGIS QgsMapCanvas
widgets.

Thanks,
Eric

On Wed, Mar 3, 2021 at 11:00 AM Martin Dobias <wonder.sk at gmail.com> wrote:

> Hi Eric
>
> On Wed, Mar 3, 2021 at 3:48 PM Eric Younkin - NOAA Federal <
> eric.g.younkin at noaa.gov> wrote:
>
>> Looking for some advice.  We have a need to use OpenGL to draw the
>> symbology associated with some vector data.  All of our code uses OpenGL
>> 1.x.  I was thinking we could use the QOpenGLWidget and the QgsPluginLayer
>> to add our OpenGL rendered symbology to a QgsMapCanvas as a new layer.
>>
>> Is this possible?  Is there an example anyone knows of that is kind of
>> similar to this idea?  Or is there a better way to approach this problem?
>>
>
> Could you please provide some more details regarding the symbology you
> would like to get rendered? A screenshot would help a lot...
>
> If you plan to use mesh-based weather data, maybe what you are trying to
> do is already possible with the mesh layer in QGIS out of the box (e.g.
> display of arrows, streamlines, trace animation), or there is only small
> amount of extra work do be done in QGIS core to achieve that.
>
> As for OpenGL approach (it looks like you already have some existing code
> you would like to adapt to QGIS)... are you looking just at 2D rendering or
> 3D rendering as well? I know some time ago for QGIS 2.x Vincent Mora has
> created a plugin layer that used OpenGL to render to offscreen image and
> then draw it in map canvas [1] which involved some hacks. With
> QOpenGLWidget approach I would be quite cautious as it may not work well,
> or have some strange issues on different platforms. For example, I _think_
> the QOpenGLWidget can't be semi-transparent (but I may be wrong), so mixing
> its content with the rest of the map could be quite tricky...
>
> Regards
> Martin
>
> [1] https://github.com/Oslandia/meshlayer
>


-- 
Eric Younkin
Physical Scientist
NOAA OCS, Hydrographic Systems and Technology Branch
1315 East-West Highway
N/CS11, Room 6604
Silver Spring, MD 20910
Office: 240-847-8208
Cell: 828-331-8197
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20210303/71f6cc81/attachment.html>