[SailfishDevel] OpenGL Under Selica QML

[David Greaves]

On 22/01/14 08:37, Wim de Vries wrote:
> Hi,
> Some time ago Thomas Perl was so kind to supply us with an example 'OpenGL Over
> QML'.
> It uses the afterRendering() signal.
> I am trying to use the beforeRendering() signal (including
> setClearBeforeRendering(false)), but I get no OpenGL output.
> It works with standard (non-Selica) QML.
> I have the strong feeling that this is impossible because the ApplicationWindow,
> Page or other Silica items do paint the whole screen, overwriting the OpenGL area.
> Am I right?
Yes

> If yes, is there a way to get around it?
No

> Basically I want the (Silica) QML painted (partly transparent) over the OpenGL.
> Thanks.

The other option is to render to an FBO and then assign that to a QML item

http://qt-project.org/doc/qt-5/qtquick-visualcanvas-scenegraph.html#mixing-scene-graph-and-opengl

AFAIUI it's slightly lower performance but it does give you total control over
layering your GLES window into your QML.

David