Added cvQTcameraGL to the project.

Author: karlphillip

README.md

@@ -14,3 +14,7 @@ An application that shows how to create a Qt window to display videos loaded wit
 cvImage
 --------------
 A simple Qt/OpenCV example that displays an image and the RGB values of a pixel based on the mouse coordinates.
+
+cvQTcameraGL
+--------------
+This application uses OpenCV to retrieve frames from the camera and display them on a QGLWidget.

cvQTcameraGL/cvQTcameraGL.pro

@@ -0,0 +1,53 @@
+QT += core gui opengl
+
+contains(QT_VERSION, ^5\\.[0-8]\\..*) {
+    message("* Using Qt $${QT_VERSION}.")
+    QT += widgets
+
+    # On my system I have to specify g++ as compiler else it will use clang++ by default
+    #QMAKE_CXX=g++
+    #QMAKE_CC=gcc
+}
+
+SOURCES += \
+    main.cpp \
+    widget.cpp
+
+HEADERS += \
+    widget.h
+
+## OpenCV settings for Unix/Linux
+unix:!mac {
+    message("* Using settings for Unix/Linux.")
+    INCLUDEPATH += /usr/local/include/opencv
+
+    LIBS += -L/usr/local/lib/ \
+        -lopencv_core \
+        -lopencv_highgui \
+        -lopencv_imgproc
+}
+
+## OpenCV settings for Mac OS X
+macx {
+    message("* Using settings for Mac OS X.")
+    INCLUDEPATH += /usr/local/include/opencv
+
+    LIBS += -L/usr/local/lib/ \
+        -lopencv_core \
+        -lopencv_highgui \
+        -lopencv_imgproc
+}
+
+## OpenCV settings for Windows and OpenCV 2.4.2
+win32 {
+    message("* Using settings for Windows.")
+    INCLUDEPATH += "C:\\opencv\\build\\include" \
+                   "C:\\opencv\\build\\include\\opencv" \
+                   "C:\\opencv\\build\\include\\opencv2"
+
+    LIBS += -L"C:\\opencv\\build\\x86\\vc10\\lib" \
+        -lopencv_core242 \
+        -lopencv_highgui242 \
+        -lopencv_imgproc242
+}
+

cvQTcameraGL/main.cpp

@@ -0,0 +1,14 @@
+#include <QApplication>
+#include "widget.h"
+
+int main(int argc, char* argv[])
+{
+    QApplication app(argc, argv);
+
+    // For OpenGL Graphics
+    GLWidget gl_widget;
+    gl_widget.show();
+
+    return app.exec();
+}
+

cvQTcameraGL/widget.cpp

@@ -0,0 +1,135 @@
+#include "widget.h"
+
+#include <iostream>
+#include <QKeyEvent>
+#include <QTimer>
+
+
+GLWidget::GLWidget(QWidget *parent)
+: QGLWidget(parent)
+{
+    _width = 0;
+    _height = 0;
+    _texture = 0;
+    _fps = 0;
+}
+
+GLWidget::~GLWidget()
+{
+    glDeleteTextures(1, &_texture);
+}
+
+void GLWidget::_tick()
+{
+    // triggers paintGL()
+    update();
+
+    // Set timer according to FPS
+    QTimer::singleShot(1000/_fps, this, SLOT(_tick()));
+}
+
+void GLWidget::initializeGL()
+{
+    // Set clear color as black
+    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+
+    // Select pixel storage mode used by glTexImage2D
+    glPixelStorei (GL_UNPACK_ALIGNMENT, 1);
+
+    // Create the texture
+    glGenTextures(1, &_texture);
+
+    /* Open default camera device */
+
+    cv_capture.open(0);
+    if (!cv_capture.isOpened())
+    {
+        std::cout << "GLWidget::initializeGL: !!! Failed to open camera" << std::endl;
+        return;
+    }
+
+    // Retrieve FPS from the camera
+    _fps = cv_capture.get(CV_CAP_PROP_FPS);
+    if (!_fps) // if the function fails, fps is set to 15
+        _fps = 15;
+
+    std::cout << "GLWidget::initializeGL: " << _fps << " fps" << std::endl;
+
+    /* Start the timer */
+
+    _tick();
+}
+
+void GLWidget::paintGL()
+{
+    // Clear the screen and depth buffer (with black)
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    // Select the model view matrix and reset it
+    glMatrixMode(GL_MODELVIEW);
+    glLoadIdentity();
+
+    glTranslatef(0.0f, 0.0f, 0.0f);
+
+    // Abort drawing if OpenCV was unable to open the camera
+    if (!cv_capture.isOpened())
+    {
+        std::cout << "GLWidget::paintGL: !!! Failed to open camera" << std::endl;
+        return;
+    }
+
+    // Note: trying to retrieve more frames than the camera can give you
+    // will make the output video blink a lot.
+    cv_capture >> cv_frame;
+    if (cv_frame.empty())
+    {
+        std::cout << "GLWidget::paintGL: !!! Failed to retrieve frame" << std::endl;
+        return;
+    }
+    cv::cvtColor(cv_frame, cv_frame, CV_BGR2RGBA);
+
+    glEnable(GL_TEXTURE_RECTANGLE_ARB);
+
+    // Typical texture generation using data from the bitmap
+    glBindTexture(GL_TEXTURE_RECTANGLE_ARB, _texture);
+
+    // Transfer image data to the GPU
+    glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0,
+                 GL_RGBA, cv_frame.cols, cv_frame.rows, 0,
+                 GL_RGBA, GL_UNSIGNED_BYTE, cv_frame.data);
+    if (glGetError() != GL_NO_ERROR)
+    {
+        std::cout << "GLWidget::paintGL: !!! Failed glTexImage2D" << std::endl;
+    }
+
+    // Draw a 2D face with texture
+    glBegin(GL_QUADS);
+        glTexCoord2f(0, 0);                         glVertex2f(1.0, 1.0);
+        glTexCoord2f(cv_frame.cols, 0);             glVertex2f(-1.0, 1.0);
+        glTexCoord2f(cv_frame.cols, cv_frame.rows); glVertex2f(-1.0, -1.0);
+        glTexCoord2f(0, cv_frame.rows);             glVertex2f(1.0, -1.0);
+    glEnd();
+
+    glDisable(GL_TEXTURE_RECTANGLE_ARB);
+}
+
+void GLWidget::resizeGL( int w, int h)
+{
+    _width = w;
+    _height = h;
+
+    glViewport(0, 0, w, h);
+    glMatrixMode(GL_PROJECTION);  // Select the projection matrix
+    glLoadIdentity();             // Reset the projection matrix
+    if (h == 0)  // Calculate aspect ratio of the window
+       gluPerspective(60, (float) w, 1.0, 50.0);
+    else
+       gluPerspective(60, (float) w / (float) h, 1.0, 50.0);
+
+    gluLookAt(0.0,  0.0, 2.0,   // eye
+              0.0,  0.0, 0.0,   // center
+              0.0,  1.0, 0.0);  // up
+
+    glMatrixMode(GL_MODELVIEW);  // Select the model view matrix
+    glLoadIdentity();           // Reset the model view matrix
+}

cvQTcameraGL/widget.h

@@ -0,0 +1,30 @@
+#pragma once
+#include <cv.h>
+#include <highgui.h>
+#include <QGLWidget>
+#include <QImage>
+
+class GLWidget : public QGLWidget
+{
+    Q_OBJECT
+public:
+    explicit GLWidget(QWidget* parent = 0);
+    virtual ~GLWidget();
+
+    /* OpenGL initialization, viewport resizing, and painting */
+
+    void initializeGL();
+    void paintGL();
+    void resizeGL( int width, int height);
+
+private:
+    int _width;
+    int _height;
+    cv::Mat cv_frame;
+    cv::VideoCapture cv_capture;
+    int _fps;
+    GLuint  _texture;
+
+protected slots:
+    void _tick();
+};