[Development] Problems running Qt3D examples

Christian Gagneraud chgans at gna.org
Tue Mar 24 01:09:23 CET 2015

Hi there,

I've just build qt5 from git (5.5 branch, commit cdc3bf5) and I'm having 
problems running some qt3d examples.

I've run *all* examples and only a few don't work:
- assimp, multiviewport: window content is black
- gltf: window content is never drawn

Don't know if it's related, but the following examples gives me a 
warning message 'Xlib: extension "NV-GLX" missing on display ":0"' but 
run fine:
- simple-cpp
- materials
- loader-qml
- deferred-renderer-qml
- deferred-renderer-cpp
- cylinder-cpp
- cpp_example
- wave
- wireframe

These one don't run and give me the NV-GLX warning:
- gltf
- assimp

These ones don't run and don't produce the NV-GLX warning:
- multiviewport

Some examples produce as well messages like 'Xlib: sequence lost 
(0x1026b > 0x26d) in reply type 0x23!':
- shadow-map-qml
- deferred-renderer-qml
- defered-renderer-cpp

All other examples run fine with no Xlib warnings.

I'm running KUbuntu 14.10, with all the updates, my GPU config is:
GL_VERSION:  4.4.0 NVIDIA 331.113
GL_VENDOR:   NVIDIA Corporation

I'm not sure what the problem is, is it a Qt issue, an NVIDIA driver 
issue or maybe i'm missing some libs or using the wrong OpenGL lib?

Here are some libs debugging info:
$ LD_DEBUG=libs ./assimp/assimp 2>&1 | grep -i gl | grep -v libglib
      26728:     find library=libGL.so.1 [0]; searching
      26728:       trying 
      26728:       trying file=/usr/lib/nvidia-331/libGL.so.1
      26728:     find library=libnvidia-glcore.so.331.113 [0]; searching
      26728:       trying 
      26728:     calling init: 
      26728:     calling init: /usr/lib/nvidia-331/libGL.so.1
      26728:     find library=libxcb-glx.so.0 [0]; searching
      26728:       trying 
      26728:       trying file=/usr/lib/x86_64-linux-gnu/libxcb-glx.so.0
      26728:     calling init: /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0
      26728:     calling init: 
Xlib:  extension "NV-GLX" missing on display ":0".
      26728:     calling fini: 
      26728:     calling fini: /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 [0]
      26728:     calling fini: /usr/lib/nvidia-331/libGL.so.1 [0]
      26728:     calling fini: 
/usr/lib/nvidia-331/libnvidia-glcore.so.331.113 [0]

So it looks to me that i'm using the right freshly built Qt library and 
the right NVidia proprietary drivers.

Any help appreciated,

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