Qt [c++] - No Qt3D rendering on older laptop

kevin_d

Hello Folks!

I developed a game which uses the Qt3D Engine to display a custom 3D scene.
I was now copying the programm on an older Machine (Win11, i5, 4GB Ram) and the program starts properly.
Unfortunately, the 3D Scene is not rendering (the QT3D widget remains empty).
I also installed some OpenGL drivers from Microsoft [https://apps.microsoft.com/detail/9nqpsl29bfff?hl=de-DE&gl=DE]

What am I missing to set up for Qt3D to render a scene?

best regards, kevin_d

kevin_d

btw, the System has Intel HD Graphics
Drivers: igdumd64.dll and igd10umd64.dll

8Observer8

Try this:

extern "C"
{
    __declspec(dllexport) unsigned long NvOptimusEnablement = 1;
    __declspec(dllexport) unsigned long AmdPowerXpressRequestHighPerformance = 1;
}

kevin_d

Hi!
Thanks for the tip. Unfortunately, that did not do the trick.
According to https://forum.qt.io/topic/50936/qt-5-4-sending-qdebug-to-a-file-40-aka-logging-41-solved/5, I am tracing the warnings, which say:

{Warning:} D3D11 smoke test: Failed to create vertex shader
{Warning:} Initializing RHI with DirectX backend
{Warning:} RHI: Unable to use requested RHI Api, trying to fall back on OpenGL
{Warning:} Initializing RHI with OpenGL backend
{Warning:} QOpenGLContext::makeCurrent() called with non-opengl surface 0x190509c29d0
{Warning:} QRhiGles2: Failed to make context current. Expect bad things to happen.

My DirectX Version is locally at 12

best regards, kevin_d

kevin_d

hi!
On a working machine, i get a "WARNING - Initializing RHI with DirectX backend" ...
I also installed additional DirectX-components according to https://www.microsoft.com/en-gb/download/details.aspx?id=35, but it fails nevertheless.
~kevin_d

KH-219Design

I was intrigued enough by the posted RHI warning text lines that I thought I would poke around in Qt source code for clues.

Disclaimer: I do not currently work on any program on Windows (nor DirectX specifically), so I have not attempted to reproduce this nor to run anything on Windows at all at the moment.

Based on reading source code, (and depending which Qt version—here I have assumed 6.10), it seems like in order for this to happen:

{Warning:} Initializing RHI with DirectX backend
{Warning:} RHI: Unable to use requested RHI Api, trying to fall back on OpenGL

The Qt method bool QRhiD3D11::create(QRhi::Flags flags) has to return false.

You can see the body of the method here: https://github.com/qt/qtbase/blob/v6.10.2/src/gui/rhi/qrhid3d11.cpp#L197-L419

This suggests at least two potential paths toward a deeper diagnosis:

Make sure Visual Studio has access to Qt framework debug symbols and source code, and step through QRhiD3D11::create in a debugger.
Try to write a (non Qt) small DirectX "hello world" that uses functions like createDXGIFactory2 and dxgiFactory->EnumAdapters1 (which are the functions that Qt is trying to use under the hood).

In option (2), the idea is that if you directly write some DirectX code (in a separate main that does not use Qt at all), then you can perhaps more quickly discover what part of DirectX is failing to cooperate.

I offer this in the spirit of brainstorming. Again, I am not actively developing any Windows/DirectX codebase at the moment, so my advice is certainly not "expert" in that regard. However, I have done such work in years past, and I have used the approaches (1) and (2) successfully in the past to debug similar scenarios where it was not clear to me whether Qt was misbehaving or whether something nested "underneath" Qt was misbehaving.

kevin_d

Hello!

Thanks for your reply.
Appearantly, the Graphic Chip does not support DirectX11 ...
Is there a way of a fallback to either OpenGL or DirectX10 ?

best regards, kevin_d

SGaist

Hi,

I think you can use the QSG_RHI_BACKEND environment variable for that.

kevin_d

Hi!
So... no chance for Direct3D10 ?

best regards, kevin_d

SGaist

Based on a quick look at older versions of the documentation, I would say no.

kevin_d

Hmm, i would fancy to have a fallback on OpenGL, when having no D3D11 ...
But it says: QOpenGLContext::makeCurrent() called with non-opengl surface ...
What does it mean? Can it be fixed?

best regards, kevin_d

SGaist

Does it happen if you set QSG_RHI_BACKEND before starting your application ?