ubuntu18.04 compile error

[hcws]

make

/usr/lib/qt5/bin/uic ImageInterface.ui -o ui_ImageInterface.h
/usr/lib/qt5/bin/uic VRenderInterface.ui -o ui_VRenderInterface.h
g++ -c -pipe -O2 -D_REENTRANT -Wall -W -fPIC -DQT_NO_DEBUG -DQT_NO_KEYWORDS -DQT_OPENGL_LIB -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_XML_LIB -DQT_CORE_LIB -I. -isystem /usr/include/libdrm -isystem /usr/include/x86_64-linux-gnu/qt5 -isystem /usr/include/x86_64-linux-gnu/qt5/QtOpenGL -isystem /usr/include/x86_64-linux-gnu/qt5/QtWidgets -isystem /usr/include/x86_64-linux-gnu/qt5/QtGui -isystem /usr/include/x86_64-linux-gnu/qt5/QtXml -isystem /usr/include/x86_64-linux-gnu/qt5/QtCore -I.moc -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o .obj/qglviewer.o qglviewer.cpp
qglviewer.cpp: In member function ‘void QGLViewer::setCamera(qglviewer::Camera*)’:
qglviewer.cpp:684:14: error: ‘screen’ was not declared in this scope
   disconnect(screen(), SIGNAL(physicalDotsPerInchChanged(qreal)), this->camera(), SLOT(setDevicePixelRatio(qreal)));
              ^~~~~~
qglviewer.cpp:684:14: note: suggested alternative: ‘QScreen’
   disconnect(screen(), SIGNAL(physicalDotsPerInchChanged(qreal)), this->camera(), SLOT(setDevicePixelRatio(qreal)));
              ^~~~~~
              QScreen
Makefile:588: recipe for target '.obj/qglviewer.o' failed
make: *** [.obj/qglviewer.o] Error 1

[GillesDebunne]

This should be fixed by #include <QScreen> at the top of this file. Updating to the latest version, which indeed has this line should fix the issue.