Provide OpenGl context to a OpenCL context

[wwolff]

Hi!
Im starting make some improvements using hardware optimizations and one of them involves share the OpenGl buffers with my OpenCL buffers.
Everything is running fine, but to enable this specific feature i need inform to the OpenCL context what OpenGL context i am using.
But the OpenCL context are prepeared to receive wgl contexts (hdc) and i dont know how can i provide my QOpenGL context and make OpenCL understand it.
Anyone have an idea how i can enable GLCL sharing using Qt?

Kind Regards.

[wwolff]

@wwolff
Hi!
I find out there is a nativeHandle function on the QOpenGLContext object, but it returns a QVariant object.
I will need typecast this return with the native type context?
Any example of QVariant typecast?

Kind Regards.

[SGaist]

Hi,

Are you looking for qvariant_cast ?

[wwolff]

@SGaist
No, my doubt is becouse the OpenCL function request a native Handle of the window AND the native handle of the context...

[SGaist]

There was a module called QtOpenCL but it was for Qt 4 with this repository being a WIP to make it work with Qt 5.

In any case, it could be an interesting starting point to help you use OpenCL with Qt

[wwolff]

Hi!
Yes i know there is a QtOpeCL Module , but what i want is get the native structures for my Rendering OpenGL Window and provide to my own OpenCL classes.
Everything is running , including the OpenCL Kernels and etc...
But i´m trying use the OpenGL->OpenCL interoperation to optimize some graphics algorithms and using Visual Studio are working fine too.

Basically in windows i need 3 structures to enable this interoperation:

HWND hWnd, 
HDC     &hDC, 
HGLRC &hRCe

The First One is the structure create when we call the CreateWindow function to create a window.
The secondOne is the structure where we store the Device Context retrieved by the GetDC(gHwnd); function.
And Finally the Last store the OpenGL Context provided by the hRC = wglCreateContext(hDC); function.

During This days i find out a private library in Qt called QPlatformNativeInterface , but i not found any documentation about it , but it seems i can get this informations from it.

Any information of how i can get a HWND structure from a QOpenGLWindow and a QGLWidget will be much Appreciated, since from a HWND i can get the DC context and from the OpenGL context i can get the HGLRC.

Otherwise, i find out too a object in the documentation called QWGLNativeContext defined in the Qt Platform Headers , and it seems this object can be typecasted in the nativeHandle method of the QOpenGLContext class , providing this two structures...

I will do some more tests , but if this last object works i dont need use the private library to access it.

Kind Regards.

[wwolff]

Hi!

I find in the documentation the following code:

QVariant nativeHandle = context->nativeHandle();
if (!nativeHandle.isNull() && nativeHandle.canConvert<QWGLNativeContext>()) {
    QWGLNativeContext nativeContext = nativeHandle.value<QWGLNativeContext>();
    HGLRC hglrc = nativeContext.context();
    ...
}

If everything goes ok, this is exactly what i was looking for!

Kind Regards.

[wwolff]

Ok, i Almost there...

Now i´m having problems with a function called GetDC(HWND) of windows.

Basically this function get the device context needed...

Everythig compiles , but when Qt compile the main module i receive a Link error becouse it not find the definition of this windows function.

Any tip to solved it?

Kind Regards.

[SGaist]

That's a function from the User32 library. You need to link against it.