Cleanup QtOpenGL examples

Cleanup the OpenGL examples
 - use nullptr (clang-tidy)
 - use member-initialization
 - avoid redundant checks for != nullptr when deleting a pointer

Change-Id: I3e4702690ed79e71c3e952d51ceef83b907b45b7
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

23 files changed, 111 insertions, 193 deletions

diff --git a/examples/opengl/computegles31/glwindow.cpp b/examples/opengl/computegles31/glwindow.cpp
index 7a14cba66d..2194137cfd 100644
--- a/examples/opengl/computegles31/glwindow.cpp
+++ b/examples/opengl/computegles31/glwindow.cpp
@@ -73,15 +73,6 @@
 #endif
 
 GLWindow::GLWindow()
-    : m_texImageInput(0),
-      m_texImageTmp(0),
-      m_texImageProcessed(0),
-      m_shaderDisplay(0),
-      m_shaderComputeV(0),
-      m_shaderComputeH(0),
-      m_blurRadius(0.0f),
-      m_animate(true),
-      m_vao(0)
 {
     const float animationStart = 0.0;
     const float animationEnd = 10.0;
@@ -324,27 +315,18 @@ void GLWindow::initializeGL()
              << ((ctx->format().renderableType() == QSurfaceFormat::OpenGLES) ? (" GLES") : (" GL"))
              << " context";
 
-    if (m_texImageInput) {
-        delete m_texImageInput;
-        m_texImageInput = 0;
-    }
     QImage img(":/Qt-logo-medium.png");
     Q_ASSERT(!img.isNull());
+    delete m_texImageInput;
     m_texImageInput = new QOpenGLTexture(img.convertToFormat(QImage::Format_RGBA8888).mirrored());
 
-    if (m_texImageTmp) {
-        delete m_texImageTmp;
-        m_texImageTmp = 0;
-    }
+    delete m_texImageTmp;
     m_texImageTmp = new QOpenGLTexture(QOpenGLTexture::Target2D);
     m_texImageTmp->setFormat(m_texImageInput->format());
     m_texImageTmp->setSize(m_texImageInput->width(),m_texImageInput->height());
     m_texImageTmp->allocateStorage(QOpenGLTexture::RGBA,QOpenGLTexture::UInt8); // WTF?
 
-    if (m_texImageProcessed) {
-        delete m_texImageProcessed;
-        m_texImageProcessed = 0;
-    }
+    delete m_texImageProcessed;
     m_texImageProcessed = new QOpenGLTexture(QOpenGLTexture::Target2D);
     m_texImageProcessed->setFormat(m_texImageInput->format());
     m_texImageProcessed->setSize(m_texImageInput->width(),m_texImageInput->height());
@@ -354,10 +336,7 @@ void GLWindow::initializeGL()
     m_texImageProcessed->setMinificationFilter(QOpenGLTexture::Linear);
     m_texImageProcessed->setWrapMode(QOpenGLTexture::ClampToEdge);
 
-    if (m_shaderDisplay) {
-        delete m_shaderDisplay;
-        m_shaderDisplay = 0;
-    }
+    delete m_shaderDisplay;
     m_shaderDisplay = new QOpenGLShaderProgram;
     // Prepend the correct version directive to the sources. The rest is the
     // same, thanks to the common GLSL syntax.
@@ -365,18 +344,12 @@ void GLWindow::initializeGL()
     m_shaderDisplay->addShaderFromSourceCode(QOpenGLShader::Fragment, versionedShaderCode(fsDisplaySource));
     m_shaderDisplay->link();
 
-    if (m_shaderComputeV) {
-        delete m_shaderComputeV;
-        m_shaderComputeV = 0;
-    }
+    delete m_shaderComputeV;
     m_shaderComputeV = new QOpenGLShaderProgram;
     m_shaderComputeV->addShaderFromSourceCode(QOpenGLShader::Compute, versionedShaderCode(csComputeSourceV));
     m_shaderComputeV->link();
 
-    if (m_shaderComputeH) {
-        delete m_shaderComputeH;
-        m_shaderComputeH = 0;
-    }
+    delete m_shaderComputeH;
     m_shaderComputeH = new QOpenGLShaderProgram;
     m_shaderComputeH->addShaderFromSourceCode(QOpenGLShader::Compute, versionedShaderCode(csComputeSourceH));
     m_shaderComputeH->link();
diff --git a/examples/opengl/computegles31/glwindow.h b/examples/opengl/computegles31/glwindow.h
index f243858a45..5375fbb488 100644
--- a/examples/opengl/computegles31/glwindow.h
+++ b/examples/opengl/computegles31/glwindow.h
@@ -90,21 +90,21 @@ protected:
     void setAnimating(bool animate);
 
 private:
-    QPropertyAnimation *m_animationForward;
-    QPropertyAnimation *m_animationBackward;
+    QPropertyAnimation *m_animationForward = nullptr;
+    QPropertyAnimation *m_animationBackward = nullptr;
     QSequentialAnimationGroup *m_animationGroup;
-    QOpenGLTexture *m_texImageInput;
-    QOpenGLTexture *m_texImageTmp;
-    QOpenGLTexture *m_texImageProcessed;
-    QOpenGLShaderProgram *m_shaderDisplay;
-    QOpenGLShaderProgram *m_shaderComputeV;
-    QOpenGLShaderProgram *m_shaderComputeH;
+    QOpenGLTexture *m_texImageInput = nullptr;
+    QOpenGLTexture *m_texImageTmp = nullptr;
+    QOpenGLTexture *m_texImageProcessed = nullptr;
+    QOpenGLShaderProgram *m_shaderDisplay = nullptr;
+    QOpenGLShaderProgram *m_shaderComputeV = nullptr;
+    QOpenGLShaderProgram *m_shaderComputeH = nullptr;
     QMatrix4x4 m_proj;
     QSizeF     m_quadSize;
 
-    int m_blurRadius;
-    bool m_animate;
-    QOpenGLVertexArrayObject *m_vao;
+    int m_blurRadius = 0;
+    bool m_animate = true;
+    QOpenGLVertexArrayObject *m_vao = nullptr;
 };
 
 #endif
diff --git a/examples/opengl/contextinfo/renderwindow.cpp b/examples/opengl/contextinfo/renderwindow.cpp
index 21b7434be6..ea9a7a24cb 100644
--- a/examples/opengl/contextinfo/renderwindow.cpp
+++ b/examples/opengl/contextinfo/renderwindow.cpp
@@ -56,7 +56,7 @@
 #include <QOpenGLFunctions>
 
 RenderWindow::RenderWindow(const QSurfaceFormat &format)
-    : m_context(0),
+    : m_context(nullptr),
       m_initialized(false),
       m_forceGLSL110(false),
       m_angle(0.0f)
@@ -67,7 +67,7 @@ RenderWindow::RenderWindow(const QSurfaceFormat &format)
     m_context->setFormat(requestedFormat());
     if (!m_context->create()) {
         delete m_context;
-        m_context = 0;
+        m_context = nullptr;
     }
 }
 
diff --git a/examples/opengl/contextinfo/widget.h b/examples/opengl/contextinfo/widget.h
index 72abe0e647..85d181a229 100644
--- a/examples/opengl/contextinfo/widget.h
+++ b/examples/opengl/contextinfo/widget.h
@@ -64,7 +64,7 @@ class Widget : public QWidget
     Q_OBJECT
 
 public:
-    explicit Widget(QWidget *parent = 0);
+    explicit Widget(QWidget *parent = nullptr);
 
 private slots:
     void start();
diff --git a/examples/opengl/cube/geometryengine.cpp b/examples/opengl/cube/geometryengine.cpp
index 1f9e16a935..24e014201e 100644
--- a/examples/opengl/cube/geometryengine.cpp
+++ b/examples/opengl/cube/geometryengine.cpp
@@ -174,6 +174,6 @@ void GeometryEngine::drawCubeGeometry(QOpenGLShaderProgram *program)
     program->setAttributeBuffer(texcoordLocation, GL_FLOAT, offset, 2, sizeof(VertexData));
 
     // Draw cube geometry using indices from VBO 1
-    glDrawElements(GL_TRIANGLE_STRIP, 34, GL_UNSIGNED_SHORT, 0);
+    glDrawElements(GL_TRIANGLE_STRIP, 34, GL_UNSIGNED_SHORT, nullptr);
 }
 //! [2]
diff --git a/examples/opengl/cube/mainwidget.cpp b/examples/opengl/cube/mainwidget.cpp
index 292a4245fa..558ecd1299 100644
--- a/examples/opengl/cube/mainwidget.cpp
+++ b/examples/opengl/cube/mainwidget.cpp
@@ -52,15 +52,7 @@
 
 #include <QMouseEvent>
 
-#include <math.h>
-
-MainWidget::MainWidget(QWidget *parent) :
-    QOpenGLWidget(parent),
-    geometries(0),
-    texture(0),
-    angularSpeed(0)
-{
-}
+#include <cmath>
 
 MainWidget::~MainWidget()
 {
diff --git a/examples/opengl/cube/mainwidget.h b/examples/opengl/cube/mainwidget.h
index cd2f8098ad..b6a03d454a 100644
--- a/examples/opengl/cube/mainwidget.h
+++ b/examples/opengl/cube/mainwidget.h
@@ -69,7 +69,7 @@ class MainWidget : public QOpenGLWidget, protected QOpenGLFunctions
     Q_OBJECT
 
 public:
-    explicit MainWidget(QWidget *parent = 0);
+    using QOpenGLWidget::QOpenGLWidget;
     ~MainWidget();
 
 protected:
@@ -87,15 +87,15 @@ protected:
 private:
     QBasicTimer timer;
     QOpenGLShaderProgram program;
-    GeometryEngine *geometries;
+    GeometryEngine *geometries = nullptr;
 
-    QOpenGLTexture *texture;
+    QOpenGLTexture *texture = nullptr;
 
     QMatrix4x4 projection;
 
     QVector2D mousePressPosition;
     QVector3D rotationAxis;
-    qreal angularSpeed;
+    qreal angularSpeed = 0;
     QQuaternion rotation;
 };
 
diff --git a/examples/opengl/hellogl2/glwidget.cpp b/examples/opengl/hellogl2/glwidget.cpp
index 318adb5043..543e70f8ac 100644
--- a/examples/opengl/hellogl2/glwidget.cpp
+++ b/examples/opengl/hellogl2/glwidget.cpp
@@ -57,11 +57,7 @@
 bool GLWidget::m_transparent = false;
 
 GLWidget::GLWidget(QWidget *parent)
-    : QOpenGLWidget(parent),
-      m_xRot(0),
-      m_yRot(0),
-      m_zRot(0),
-      m_program(0)
+    : QOpenGLWidget(parent)
 {
     m_core = QSurfaceFormat::defaultFormat().profile() == QSurfaceFormat::CoreProfile;
     // --transparent causes the clear color to be transparent. Therefore, on systems that
@@ -133,7 +129,7 @@ void GLWidget::cleanup()
     makeCurrent();
     m_logoVbo.destroy();
     delete m_program;
-    m_program = 0;
+    m_program = nullptr;
     doneCurrent();
 }
 
@@ -250,8 +246,10 @@ void GLWidget::setupVertexAttribs()
     QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
     f->glEnableVertexAttribArray(0);
     f->glEnableVertexAttribArray(1);
-    f->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), 0);
-    f->glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), reinterpret_cast<void *>(3 * sizeof(GLfloat)));
+    f->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat),
+                             nullptr);
+    f->glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat),
+                             reinterpret_cast<void *>(3 * sizeof(GLfloat)));
     m_logoVbo.release();
 }
 
diff --git a/examples/opengl/hellogl2/glwidget.h b/examples/opengl/hellogl2/glwidget.h
index 21dd200dc7..f8526fb7ae 100644
--- a/examples/opengl/hellogl2/glwidget.h
+++ b/examples/opengl/hellogl2/glwidget.h
@@ -65,7 +65,7 @@ class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions
     Q_OBJECT
 
 public:
-    GLWidget(QWidget *parent = 0);
+    GLWidget(QWidget *parent = nullptr);
     ~GLWidget();
 
     static bool isTransparent() { return m_transparent; }
@@ -96,18 +96,18 @@ private:
     void setupVertexAttribs();
 
     bool m_core;
-    int m_xRot;
-    int m_yRot;
-    int m_zRot;
+    int m_xRot = 0;
+    int m_yRot = 0;
+    int m_zRot = 0;
     QPoint m_lastPos;
     Logo m_logo;
     QOpenGLVertexArrayObject m_vao;
     QOpenGLBuffer m_logoVbo;
-    QOpenGLShaderProgram *m_program;
-    int m_projMatrixLoc;
-    int m_mvMatrixLoc;
-    int m_normalMatrixLoc;
-    int m_lightPosLoc;
+    QOpenGLShaderProgram *m_program = nullptr;
+    int m_projMatrixLoc = 0;
+    int m_mvMatrixLoc = 0;
+    int m_normalMatrixLoc = 0;
+    int m_lightPosLoc = 0;
     QMatrix4x4 m_proj;
     QMatrix4x4 m_camera;
     QMatrix4x4 m_world;
diff --git a/examples/opengl/hellogl2/logo.cpp b/examples/opengl/hellogl2/logo.cpp
index a1ec8eaebe..6fcece16d4 100644
--- a/examples/opengl/hellogl2/logo.cpp
+++ b/examples/opengl/hellogl2/logo.cpp
@@ -52,7 +52,6 @@
 #include <qmath.h>
 
 Logo::Logo()
-    : m_count(0)
 {
     m_data.resize(2500 * 6);
 
diff --git a/examples/opengl/hellogl2/logo.h b/examples/opengl/hellogl2/logo.h
index 9e04a57e86..2f3dc7e649 100644
--- a/examples/opengl/hellogl2/logo.h
+++ b/examples/opengl/hellogl2/logo.h
@@ -69,7 +69,7 @@ private:
     void add(const QVector3D &v, const QVector3D &n);
 
     QVector<GLfloat> m_data;
-    int m_count;
+    int m_count = 0;
 };
 
 #endif // LOGO_H
diff --git a/examples/opengl/hellogl2/mainwindow.cpp b/examples/opengl/hellogl2/mainwindow.cpp
index 6bfdee7785..aa20cd678c 100644
--- a/examples/opengl/hellogl2/mainwindow.cpp
+++ b/examples/opengl/hellogl2/mainwindow.cpp
@@ -72,5 +72,6 @@ void MainWindow::onAddNew()
     if (!centralWidget())
         setCentralWidget(new Window(this));
     else
-        QMessageBox::information(0, tr("Cannot add new window"), tr("Already occupied. Undock first."));
+        QMessageBox::information(nullptr, tr("Cannot add new window"),
+                                 tr("Already occupied. Undock first."));
 }
diff --git a/examples/opengl/hellogl2/window.cpp b/examples/opengl/hellogl2/window.cpp
index c3cd10cbfd..5534f2edea 100644
--- a/examples/opengl/hellogl2/window.cpp
+++ b/examples/opengl/hellogl2/window.cpp
@@ -121,7 +121,7 @@ void Window::keyPressEvent(QKeyEvent *e)
 void Window::dockUndock()
 {
     if (parent()) {
-        setParent(0);
+        setParent(nullptr);
         setAttribute(Qt::WA_DeleteOnClose);
         move(QApplication::desktop()->width() / 2 - width() / 2,
              QApplication::desktop()->height() / 2 - height() / 2);
@@ -134,10 +134,12 @@ void Window::dockUndock()
                 dockBtn->setText(tr("Undock"));
                 mainWindow->setCentralWidget(this);
             } else {
-                QMessageBox::information(0, tr("Cannot dock"), tr("Main window already closed"));
+                QMessageBox::information(nullptr, tr("Cannot dock"),
+                                         tr("Main window already closed"));
             }
         } else {
-            QMessageBox::information(0, tr("Cannot dock"), tr("Main window already occupied"));
+            QMessageBox::information(nullptr, tr("Cannot dock"),
+                                     tr("Main window already occupied"));
         }
     }
 }
diff --git a/examples/opengl/hellogles3/glwindow.cpp b/examples/opengl/hellogles3/glwindow.cpp
index 9458b74810..c644faa9a6 100644
--- a/examples/opengl/hellogles3/glwindow.cpp
+++ b/examples/opengl/hellogles3/glwindow.cpp
@@ -57,19 +57,10 @@
 #include <QOpenGLVertexArrayObject>
 #include <QOpenGLExtraFunctions>
 #include <QPropertyAnimation>
-#include <QPauseAnimation>
 #include <QSequentialAnimationGroup>
 #include <QTimer>
 
 GLWindow::GLWindow()
-    : m_texture(0),
-      m_program(0),
-      m_vbo(0),
-      m_vao(0),
-      m_target(0, 0, -1),
-      m_uniformsDirty(true),
-      m_r(0),
-      m_r2(0)
 {
     m_world.setToIdentity();
     m_world.translate(0, 0, -1);
@@ -197,18 +188,12 @@ void GLWindow::initializeGL()
 {
     QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
 
-    if (m_texture) {
-        delete m_texture;
-        m_texture = 0;
-    }
     QImage img(":/qtlogo.png");
     Q_ASSERT(!img.isNull());
+    delete m_texture;
     m_texture = new QOpenGLTexture(img.scaled(32, 36).mirrored());
 
-    if (m_program) {
-        delete m_program;
-        m_program = 0;
-    }
+    delete m_program;
     m_program = new QOpenGLShaderProgram;
     // Prepend the correct version directive to the sources. The rest is the
     // same, thanks to the common GLSL syntax.
@@ -223,26 +208,21 @@ void GLWindow::initializeGL()
     m_lightPosLoc = m_program->uniformLocation("lightPos");
 
     // Create a VAO. Not strictly required for ES 3, but it is for plain OpenGL.
-    if (m_vao) {
-        delete m_vao;
-        m_vao = 0;
-    }
+    delete m_vao;
     m_vao = new QOpenGLVertexArrayObject;
     if (m_vao->create())
         m_vao->bind();
 
-    if (m_vbo) {
-        delete m_vbo;
-        m_vbo = 0;
-    }
     m_program->bind();
+    delete m_vbo;
     m_vbo = new QOpenGLBuffer;
     m_vbo->create();
     m_vbo->bind();
     m_vbo->allocate(m_logo.constData(), m_logo.count() * sizeof(GLfloat));
     f->glEnableVertexAttribArray(0);
     f->glEnableVertexAttribArray(1);
-    f->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), 0);
+    f->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat),
+                             nullptr);
     f->glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat),
                              reinterpret_cast<void *>(3 * sizeof(GLfloat)));
     m_vbo->release();
diff --git a/examples/opengl/hellogles3/glwindow.h b/examples/opengl/hellogles3/glwindow.h
index fba997bee4..dfa0680714 100644
--- a/examples/opengl/hellogles3/glwindow.h
+++ b/examples/opengl/hellogles3/glwindow.h
@@ -90,23 +90,23 @@ public:
 private slots:
     void startSecondStage();
 private:
-    QOpenGLTexture *m_texture;
-    QOpenGLShaderProgram *m_program;
-    QOpenGLBuffer *m_vbo;
-    QOpenGLVertexArrayObject *m_vao;
+    QOpenGLTexture *m_texture = nullptr;
+    QOpenGLShaderProgram *m_program = nullptr;
+    QOpenGLBuffer *m_vbo = nullptr;
+    QOpenGLVertexArrayObject *m_vao = nullptr;
     Logo m_logo;
-    int m_projMatrixLoc;
-    int m_camMatrixLoc;
-    int m_worldMatrixLoc;
-    int m_myMatrixLoc;
-    int m_lightPosLoc;
+    int m_projMatrixLoc = 0;
+    int m_camMatrixLoc = 0;
+    int m_worldMatrixLoc = 0;
+    int m_myMatrixLoc = 0;
+    int m_lightPosLoc = 0;
     QMatrix4x4 m_proj;
     QMatrix4x4 m_world;
     QVector3D m_eye;
-    QVector3D m_target;
-    bool m_uniformsDirty;
-    float m_r;
-    float m_r2;
+    QVector3D m_target = {0, 0, -1};
+    bool m_uniformsDirty = true;
+    float m_r = 0;
+    float m_r2 = 0;
 };
 
 #endif
diff --git a/examples/opengl/qopenglwidget/bubble.cpp b/examples/opengl/qopenglwidget/bubble.cpp
index dbaf460f6f..7e69aac3e7 100644
--- a/examples/opengl/qopenglwidget/bubble.cpp
+++ b/examples/opengl/qopenglwidget/bubble.cpp
@@ -57,15 +57,13 @@ Bubble::Bubble(const QPointF &position, qreal radius, const QPointF &velocity)
 {
     innerColor = randomColor();
     outerColor = randomColor();
-    cache = 0;
     updateBrush();
 }
 
 //! [0]
 void Bubble::updateCache()
 {
-    if (cache)
-        delete cache;
+    delete cache;
     cache = new QImage(qRound(radius * 2 + 2), qRound(radius * 2 + 2), QImage::Format_ARGB32_Premultiplied);
     cache->fill(0x00000000);
     QPainter p(cache);
@@ -80,8 +78,7 @@ void Bubble::updateCache()
 
 Bubble::~Bubble()
 {
-    if (cache)
-        delete cache;
+    delete cache;
 }
 
 void Bubble::updateBrush()
diff --git a/examples/opengl/qopenglwidget/bubble.h b/examples/opengl/qopenglwidget/bubble.h
index 7170803b40..833ea02288 100644
--- a/examples/opengl/qopenglwidget/bubble.h
+++ b/examples/opengl/qopenglwidget/bubble.h
@@ -80,7 +80,7 @@ private:
     qreal radius;
     QColor innerColor;
     QColor outerColor;
-    QImage *cache;
+    QImage *cache = nullptr;
 };
 
 #endif
diff --git a/examples/opengl/qopenglwidget/glwidget.cpp b/examples/opengl/qopenglwidget/glwidget.cpp
index 5057291f12..89c8469662 100644
--- a/examples/opengl/qopenglwidget/glwidget.cpp
+++ b/examples/opengl/qopenglwidget/glwidget.cpp
@@ -68,14 +68,6 @@ const int bubbleNum = 8;
 
 GLWidget::GLWidget(MainWindow *mw, bool button, const QColor &background)
     : m_mainWindow(mw),
-      m_showBubbles(true),
-      m_qtLogo(true),
-      m_frames(0),
-      m_program1(0),
-      m_program2(0),
-      m_texture(0),
-      m_transparent(false),
-      m_btn(0),
       m_hasButton(button),
       m_background(background)
 {
diff --git a/examples/opengl/qopenglwidget/glwidget.h b/examples/opengl/qopenglwidget/glwidget.h
index 0ad2581cb8..99288261c0 100644
--- a/examples/opengl/qopenglwidget/glwidget.h
+++ b/examples/opengl/qopenglwidget/glwidget.h
@@ -98,34 +98,34 @@ private:
     void extrude(qreal x1, qreal y1, qreal x2, qreal y2);
 
     MainWindow *m_mainWindow;
-    qreal m_fAngle;
-    qreal m_fScale;
-    bool m_showBubbles;
+    qreal m_fAngle = 0;
+    qreal m_fScale = 1;
+    bool m_showBubbles = true;
     QVector<QVector3D> m_vertices;
     QVector<QVector3D> m_normals;
-    bool m_qtLogo;
-    QList<Bubble *> m_bubbles;
-    int m_frames;
+    bool m_qtLogo = true;
+    QVector<Bubble *> m_bubbles;
+    int m_frames = 0;
     QElapsedTimer m_time;
-    QOpenGLShader *m_vshader1;
-    QOpenGLShader *m_fshader1;
-    QOpenGLShader *m_vshader2;
-    QOpenGLShader *m_fshader2;
-    QOpenGLShaderProgram *m_program1;
-    QOpenGLShaderProgram *m_program2;
-    QOpenGLTexture *m_texture;
+    QOpenGLShader *m_vshader1 = nullptr;
+    QOpenGLShader *m_fshader1 = nullptr;
+    QOpenGLShader *m_vshader2 = nullptr;
+    QOpenGLShader *m_fshader2 = nullptr;
+    QOpenGLShaderProgram *m_program1 = nullptr;
+    QOpenGLShaderProgram *m_program2 = nullptr;
+    QOpenGLTexture *m_texture = nullptr;
     QOpenGLBuffer m_vbo1;
     QOpenGLBuffer m_vbo2;
-    int m_vertexAttr1;
-    int m_normalAttr1;
-    int m_matrixUniform1;
-    int m_vertexAttr2;
-    int m_normalAttr2;
-    int m_texCoordAttr2;
-    int m_matrixUniform2;
-    int m_textureUniform2;
-    bool m_transparent;
-    QPushButton *m_btn;
+    int m_vertexAttr1 = 0;
+    int m_normalAttr1 = 0;
+    int m_matrixUniform1 = 0;
+    int m_vertexAttr2 = 0;
+    int m_normalAttr2 = 0;
+    int m_texCoordAttr2 = 0;
+    int m_matrixUniform2 = 0;
+    int m_textureUniform2 = 0;
+    bool m_transparent = false;
+    QPushButton *m_btn = nullptr;
     bool m_hasButton;
     QColor m_background;
 };
diff --git a/examples/opengl/textures/glwidget.cpp b/examples/opengl/textures/glwidget.cpp
index 1644233614..307190f308 100644
--- a/examples/opengl/textures/glwidget.cpp
+++ b/examples/opengl/textures/glwidget.cpp
@@ -53,17 +53,6 @@
 #include <QOpenGLTexture>
 #include <QMouseEvent>
 
-GLWidget::GLWidget(QWidget *parent)
-    : QOpenGLWidget(parent),
-      clearColor(Qt::black),
-      xRot(0),
-      yRot(0),
-      zRot(0),
-      program(0)
-{
-    memset(textures, 0, sizeof(textures));
-}
-
 GLWidget::~GLWidget()
 {
     makeCurrent();
diff --git a/examples/opengl/textures/glwidget.h b/examples/opengl/textures/glwidget.h
index 0db2695c6a..585d44dbfe 100644
--- a/examples/opengl/textures/glwidget.h
+++ b/examples/opengl/textures/glwidget.h
@@ -63,7 +63,7 @@ class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions
     Q_OBJECT
 
 public:
-    explicit GLWidget(QWidget *parent = 0);
+    using QOpenGLWidget::QOpenGLWidget;
     ~GLWidget();
 
     QSize minimumSizeHint() const override;
@@ -85,13 +85,13 @@ protected:
 private:
     void makeObject();
 
-    QColor clearColor;
+    QColor clearColor = Qt::black;
     QPoint lastPos;
-    int xRot;
-    int yRot;
-    int zRot;
-    QOpenGLTexture *textures[6];
-    QOpenGLShaderProgram *program;
+    int xRot = 0;
+    int yRot = 0;
+    int zRot = 0;
+    QOpenGLTexture *textures[6] = {nullptr, nullptr, nullptr, nullptr, nullptr, nullptr};
+    QOpenGLShaderProgram *program = nullptr;
     QOpenGLBuffer vbo;
 };
 
diff --git a/examples/opengl/threadedqopenglwidget/glwidget.cpp b/examples/opengl/threadedqopenglwidget/glwidget.cpp
index cc528a734a..2101575fd4 100644
--- a/examples/opengl/threadedqopenglwidget/glwidget.cpp
+++ b/examples/opengl/threadedqopenglwidget/glwidget.cpp
@@ -115,12 +115,7 @@ void GLWidget::grabContext()
     m_renderer->unlockRenderer();
 }
 
-Renderer::Renderer(GLWidget *w)
-    : m_inited(false),
-      m_glwidget(w),
-      m_exiting(false)
-{
-}
+Renderer::Renderer(GLWidget *w) : m_glwidget(w) {}
 
 void Renderer::paintQtLogo()
 {
diff --git a/examples/opengl/threadedqopenglwidget/glwidget.h b/examples/opengl/threadedqopenglwidget/glwidget.h
index c33f7e51a7..8dc84dd0b1 100644
--- a/examples/opengl/threadedqopenglwidget/glwidget.h
+++ b/examples/opengl/threadedqopenglwidget/glwidget.h
@@ -88,29 +88,29 @@ private:
     void quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4);
     void extrude(qreal x1, qreal y1, qreal x2, qreal y2);
 
-    bool m_inited;
-    qreal m_fAngle;
-    qreal m_fScale;
+    bool m_inited = false;
+    qreal m_fAngle = 0;
+    qreal m_fScale = 1;
     QVector<QVector3D> vertices;
     QVector<QVector3D> normals;
     QOpenGLShaderProgram program;
     QOpenGLBuffer vbo;
-    int vertexAttr;
-    int normalAttr;
-    int matrixUniform;
-    GLWidget *m_glwidget;
+    int vertexAttr = 0;
+    int normalAttr = 0;
+    int matrixUniform = 0;
+    GLWidget *m_glwidget = nullptr;
     QMutex m_renderMutex;
     QElapsedTimer m_elapsed;
     QMutex m_grabMutex;
     QWaitCondition m_grabCond;
-    bool m_exiting;
+    bool m_exiting = false;
 };
 
 class GLWidget : public QOpenGLWidget
 {
     Q_OBJECT
 public:
-    explicit GLWidget(QWidget *parent = 0);
+    explicit GLWidget(QWidget *parent = nullptr);
     ~GLWidget();
 
 protected: