[Solved] Porting Qt example to CMake (e.g. openglunderqml)

Martinoso

Hi

I would like to integrate qml into my CMake project. For that I first tried to port this example:

@$HOME/Qt/Examples/Qt-5.3/quick/scenegraph/openglunderqml@

from QMake to CMake. The QMake project compiles fine.

My CMakeLists.txt is

@
cmake_minimum_required(VERSION 2.8 FATAL_ERROR)

project(openglunderqml)

find_package(Qt5Quick REQUIRED)
find_package(Qt5Qml REQUIRED)
find_package(OpenGL REQUIRED)

qt5_add_resources(QT_QRC_SRCS openglunderqml.qrc)

The headers, qml and qrc files are added so they show up in Qt Creator.

add_executable(openglunderqml
main.cpp
main.qml
openglunderqml.qrc
squircle.cpp
squircle.h
${QT_QRC_SRCS}
)
target_link_libraries(openglunderqml Qt5::Qml Qt5::Quick ${OPENGL_LIBRARIES})
@

When I build I get following error

@
Linking CXX executable openglunderqml
Undefined symbols for architecture x86_64:
"Squircle::qt_metacall(QMetaObject::Call, int, void**)", referenced from:
vtable for QQmlPrivate::QQmlElement<Squircle> in main.cpp.o
"Squircle::qt_metacast(char const*)", referenced from:
vtable for QQmlPrivate::QQmlElement<Squircle> in main.cpp.o
"Squircle::staticMetaObject", referenced from:
int qmlRegisterType<Squircle>(char const*, int, int, char const*) in main.cpp.o
QtPrivate::MetaObjectForType<Squircle*, true>::value() in main.cpp.o
QMetaTypeIdQObject<Squircle*, true>::qt_metatype_id() in main.cpp.o
"Squircle::tChanged()", referenced from:
Squircle::setT(double) in squircle.cpp.o
"Squircle::metaObject() const", referenced from:
vtable for QQmlPrivate::QQmlElement<Squircle> in main.cpp.o
"typeinfo for Squircle", referenced from:
typeinfo for QQmlPrivate::QQmlElement<Squircle> in main.cpp.o
"vtable for SquircleRenderer", referenced from:
SquircleRenderer::~SquircleRenderer() in squircle.cpp.o
SquircleRenderer::SquircleRenderer() in squircle.cpp.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
"vtable for Squircle", referenced from:
Squircle::Squircle() in squircle.cpp.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [openglunderqml] Error 1
make[1]: *** [CMakeFiles/openglunderqml.dir/all] Error 2
make: *** [all] Error 2
@

This problem might be related to http://qt-project.org/forums/viewthread/35646/

I would like to try the posted solution but I don't know how to translate this from QMake to CMake. What does QMake do with these flags internally and what is the CMake equivalent respectively?

@
QMAKE_MACOSX_DEPLOYMENT_TARGET=10.9
macx:QMAKE_MAC_SDK=macosx10.9
@

I am on Mac OS X 10.9.4 (Mavericks) with Qt-5.3.1-0 from the online installer.

thanks a lot.

sierdzio

I think you need to add QtCore and QtGui module includes to your cmakelists file. And (maybe) include squircle header before the source file.

Edit: also, I think one needs to explicitly tell CMake to run AUTOMOC.

Martinoso

Great. It works now! I totally forgot about automoc.

Put this before add_executable
@
set(CMAKE_AUTOMOC ON)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
@

Alternatively put this at the end
@
set_target_properties(openglunderqml PROPERTIES AUTOMOC ON)
target_include_directories(openglunderqml PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
@

sierdzio

Great, thanks for sharing the solution with us. I actually plan to learn CMake in the coming weeks, so it will come in handy :-)