use OpenVC in QT Creator V 11.0.3

[PaulE]

I created a new Project, where i wanted to use Openvc to play a video. I used qmake and QT version 5.15.15. Here is the generated .pro file

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++17

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../../../opencv/build/x64/vc16/lib/ -lopencv_world480
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../../../opencv/build/x64/vc16/lib/ -lopencv_world480d
INCLUDEPATH += $$PWD/../../../../opencv/build/include
DEPENDPATH += $$PWD/../../../../opencv/build/include

I tried to open a video with a simple example

#include "mainwindow.h"
#include <QApplication>
#include "opencv2/opencv.hpp"
#include "opencv2/videoio.hpp"

using namespace cv;

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    VideoCapture cap(0);
    return a.exec();
}

When i try to run this example i get a error message

undefined reference to `cv::VideoCapture::VideoCapture(int, int)`
undefined reference to `cv::VideoCapture::~VideoCapture()`
undefined reference to `cv::VideoCapture::~VideoCapture()`

Does someone has a idea how i can fix this error?

[JonB]

@PaulE
And what compiler/kit are you using? MSVC? Or MinGW...? Because

-L$$PWD/../../../../opencv/build/x64/vc16/lib/ -lopencv_world480

looks like MSVC library in MinGW link...?

https://forum.qt.io/topic/152113/opencv-linking-undefined-references