[Interest] Qt/D3D integration through ANGLE PBuffer

Andrew Knight andrew.knight at intopalo.com
Thu Sep 24 16:30:25 CEST 2015


On 09/24/2015 05:15 PM, Thomas Sevaldrud wrote:
> This is great, thanks for very useful info!
> I'm not sure I understood Andew's part about rendering the Quick Scene 
> graph, or I may have been a bit unclear when describing the problem. 
> Basically I want to render a Qt Quick scene graph and some custom 
> OpenGL graphics into a Direct3D control (D3DImage in WPF). What Andew 
> suggests would be the other way around I think? I.e use a D3D texture 
> in the scene graph? Or did I misunderstand?

Yes, that's what I was referring to. Sorry for the misunderstanding.

> As Laszlo suggests I'll try using QQuickRenderControl to render my 
> scene into the PBuffer/D3D texture, but I must admit I am a bit 
> confused as to how this works too. For instance I'm not sure I 
> understand how to set up the QML Engine so that it is associated with 
> the QQuickRenderControl. In the QuickRenderControl example from Qt 5.5 
> it appears that they set up the QML Engine in a QQuickWindow with an 
> FBO as render target. In my case I need the EGL PBuffer as render 
> target. How would I go about doing that?

You don't need the QOpenGLFramebufferObject in this case. As Laszlo 
said, simply bind the pbuffer and it will become the current render 
target. The scene graph will render to the pbuffer and you can use that 
in your D3D scene as a normal texture.

> - Thomas
> On Thu, Sep 24, 2015 at 2:48 PM, Andrew Knight 
> <andrew.knight at intopalo.com <mailto:andrew.knight at intopalo.com>> wrote:
>     Hi Thomas,
>     On 09/24/2015 03:11 PM, Thomas Sevaldrud wrote:
>         Hi,
>         I have earlier made an implementation of Qt/D3D integration by
>         hacking into the ANGLE D3D SwapChain and extracting the
>         D3DSurface directly there.
>         However, this is a bit flakey, and I have had to change this
>         code several times when new versions of Qt and ANGLE are released.
>         So, now I want to do this the supported way through the
>         EGL_ANGLE_surface_d3d_texture_2d_share_handle extension. If I
>         understand this correctly I can set up a PBuffer-based render
>         target which I can query for a D3D texture sharing handle
>         using the eglQuerySurfacePointerANGLE extension.
>     Yes, this is possible.
>         Now, before I start coding, I wonder if anyone has an example
>         of using this extension for rendering to a D3D Texture?
>         Someone mentioned on the list earlier that there should be an
>         example of this in QtMultimedia, but I haven't been able to
>         find it.
>     The two places this extension is used are at:
>     (D3D11)
>     http://code.qt.io/cgit/qt/qtmultimedia.git/tree/src/plugins/winrt/qwinrtabstractvideorenderercontrol.cpp#n372
>     This one creates a shared texture using D3D and shares it with
>     ANGLE. This texture is updated when a video player or camera
>     queues a frame. It is bound to the pipeline with a QOpenGLTexture
>     object and eglBindTexImage().
>     (D3D9)
>     http://code.qt.io/cgit/qt/qtmultimedia.git/tree/src/plugins/wmf/evrd3dpresentengine.cpp#n451
>     This one first creates a pbuffer using EGL, gets the shared
>     texture handle from it, and then opens up the texture in D3D.
>     Both cases are therefore covered, as well as both major D3D versions.
>         Also, for the PBuffer implementation, should I create a
>         PBuffer directly through EGL, or can I use QOffsceenSurface?
>         If I understand correctly, QOffscreenSurface will be
>         implemented with a PBuffer on Windows?
>         To complicate matters even more I want to include a Quick
>         scene graph in this as well, but I suppose I can use the new
>         QQuickRenderControl class for this when I have the PBuffer
>         render target sorted out?
>     I would just render to your D3D texture (by creating it via one of
>     the ways described above) and use it in the scene graph by binding
>     its content to the currently bound QOpenGLTexture object with
>     eglBindTexImage(). You can create a QSGTexture from a
>     QOpenGLTexture by passing the texture id to
>     QSGEngine::createTextureFromId().
>         Best regards,
>         Thomas
>         _______________________________________________
>         Interest mailing list
>         Interest at qt-project.org <mailto:Interest at qt-project.org>
>         http://lists.qt-project.org/mailman/listinfo/interest

More information about the Interest mailing list