[Interest] Custom QSGGeometryNode Scene blending issue

[Roberto Garrido]

Hi all!
We have a custom QQuickItem which in turn creates a custom QSGGeometryNode.
We reimplement the QSGGeometryNode's preprocess() method in order to draw
our scene to a FrameBufferObject with a texture attached. This OpenGL
texture ID is shared with the QSGGeometryNode's material. This way, we can
render our custom OpenGL scene into a QML item. So far, so good.

However, we want to use alpha blending on some parts of our scene, in order
to let the user see the QML items behind our custom item. Something similar
to what Item::opacity value is doing, but only for a specific area of our
Item. It's like having a hole inside our Item that allows the user to see
what's behind. The information about the specific region that should be
transparent is handled inside our custom OpenGL renderer.

I've been trying to find out what Qt is doing in order to change the
opacity of a QML item, with no luck.

Any idea on how can we achieve this effect, with our Item/Node
configuration?
Thanks in advance,
Robert.

-- 
Website: http://robertogarrido.com
Twitter: http://twitter.com/che1404
LinkedIn: http://es.linkedin.com/in/robertogarrido/en
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/interest/attachments/20160606/6294a499/attachment.html>