How to compile/run a cpp file in mac

Question

I downloaded a webcam_face_pose_ex.cpp file from GitHub and now i want to compile and run it on my mac.

#include <dlib/opencv.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <dlib/image_processing/frontal_face_detector.h>
#include <dlib/image_processing/render_face_detections.h>
#include <dlib/image_processing.h>
#include <dlib/gui_widgets.h>
#include <X11/Xlib.h>

using namespace dlib;
using namespace std;

int main()
{
    try
    {
        cv::VideoCapture cap(0);
        if (!cap.isOpened())
        {
            cerr << "Unable to connect to camera" << endl;
            return 1;
        }

        image_window win;

        // Load face detection and pose estimation models.
        frontal_face_detector detector = get_frontal_face_detector();
        shape_predictor pose_model;
        deserialize("shape_predictor_68_face_landmarks.dat") >> pose_model;

        // Grab and process frames until the main window is closed by the user.
        while(!win.is_closed())
        {
            // Grab a frame
            cv::Mat temp;
            if (!cap.read(temp))
            {
                break;
            }
            // Turn OpenCV's Mat into something dlib can deal with.  Note that this just
            // wraps the Mat object, it doesn't copy anything.  So cimg is only valid as
            // long as temp is valid.  Also don't do anything to temp that would cause it
            // to reallocate the memory which stores the image as that will make cimg
            // contain dangling pointers.  This basically means you shouldn't modify temp
            // while using cimg.
            cv_image<bgr_pixel> cimg(temp);

            // Detect faces 
            std::vector<rectangle> faces = detector(cimg);
            // Find the pose of each face.
            std::vector<full_object_detection> shapes;
            for (unsigned long i = 0; i < faces.size(); ++i)
                shapes.push_back(pose_model(cimg, faces[i]));

            // Display it all on the screen
            win.clear_overlay();
            win.set_image(cimg);
            win.add_overlay(render_face_detections(shapes));
        }
    }
    catch(serialization_error& e)
    {
        cout << "You need dlib's default face landmarking model file to run this example." << endl;
        cout << "You can get it from the following URL: " << endl;
        cout << "   http://dlib.net/files/shape_predictor_68_face_landmarks.dat.bz2" << endl;
        cout << endl << e.what() << endl;
    }
    catch(exception& e)
    {
        cout << e.what() << endl;
    }
}

I tried g++ webcam_face_pose_ex.cpp command but I get:

webcam_face_pose_ex.cpp:30:10: fatal error: 'dlib/opencv.h' file not found

#include <dlib/opencv.h>
         ^~~~~~~~~~~~~~~
1 error generated.

Was Wondering what I could do to fix this?

Answer 1

The Example File Is Not Meant to be Compiled Using g++

Read the following to learn a bit about the -I flag and #include statements:

The webcam_face_pose_ex.cpp is part of a larger project and you won't be able to compile it on its own because it depends on other files. The #include directive specifies that in order to compile this program, code from the file specified by #includemust be compiled first. This means the entire dlib must be downloaded before compiling webcam_face_pose_ex.cpp. This project also requires opencv2 so we can download it and place the opencv2 folder in the dlib project folder.

Now we can open terminal and change directory into the dlib project folder and compile the file using the following command:

g++ -I. examples/webcam_face_pose_ex.cpp

Note we're specifying the directory of where to find the files specified by #include using the -I parameter as -I. this means to search the current working directory for the files. There it will find the dlib folder and dlib/opencv.h.

How ever, this isn't enough. When you execute the command, you'll encounter an error opencv2/opencv_modules.hpp: No such file or directory.

Solution

The dlib project documentation states that the examples should be built using cmake. Make sure to use cmake to compile the examples.