Modernize the OpenGL examples

Change them to use QOpenGLWidget and QOpenGLTexture.
Advocate also the usage of VBOs.

Hopeless examples, that rely on the fixed pipeline and will
not compile or work in ES and dynamic builds, are moved to
a "legacy" directory. The documentation pages for these are
removed. This long due change avoids the confusion newcomers
experience when trying to get started with Qt 5 and OpenGL.

hellowindow's behavior is changed to open a single window only
by default. The old default behavior, that opened three windows
on platforms that supported both MultipleWindows & ThreadedOpenGL,
can be requested by passing --multiple. --single is removed since it
is the default now. This plays much nicer with drivers that have
issues with threading.

In addition, say hello to hellogl2.

This is the old hellogl example updated to use QOpenGLWidget and
OpenGL 2. It also has a mainwindow with multiple (un)dockable widgets
containing the OpenGL widgets. This helps testing the behavior when
the top-level of the QOpenGLWidget changes and provides a very
important example of how to do proper resource management in this case.
(must use aboutToBeDestroyed() of the context, since the context goes
away and is replaced by a new one on every dock/undock)

As a bonus, the logo is now real 3D, no more orthographic nonsense.

Launch with --multisample to request 4x MSAA.

Launch with --coreprofile to request 3.2 Core. In this particular example
the shaders are present in both versions and there is a VAO so the application
is functional with core profile contexts.

Change-Id: Id780a80cb0708ef164cc172450ed74050f065596
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>

1 files changed, 285 insertions, 0 deletions

diff --git a/examples/opengl/legacy/overpainting/glwidget.cpp b/examples/opengl/legacy/overpainting/glwidget.cpp
new file mode 100644
index 0000000000..420ae3e881
--- /dev/null
+++ b/examples/opengl/legacy/overpainting/glwidget.cpp
@@ -0,0 +1,285 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "bubble.h"
+#include "qtlogo.h"
+#include "glwidget.h"
+
+#include <QMouseEvent>
+#include <QTime>
+
+#include <math.h>
+#include <stdlib.h>
+
+#ifndef GL_MULTISAMPLE
+#define GL_MULTISAMPLE  0x809D
+#endif
+
+//! [0]
+GLWidget::GLWidget(QWidget *parent)
+    : QGLWidget(QGLFormat(QGL::SampleBuffers), parent)
+{
+    QTime midnight(0, 0, 0);
+    qsrand(midnight.secsTo(QTime::currentTime()));
+
+    logo = 0;
+    xRot = 0;
+    yRot = 0;
+    zRot = 0;
+
+    qtGreen = QColor::fromCmykF(0.40, 0.0, 1.0, 0.0);
+    qtPurple = QColor::fromCmykF(0.39, 0.39, 0.0, 0.0);
+
+    animationTimer.setSingleShot(false);
+    connect(&animationTimer, SIGNAL(timeout()), this, SLOT(animate()));
+    animationTimer.start(25);
+
+    setAutoFillBackground(false);
+    setMinimumSize(200, 200);
+    setWindowTitle(tr("Overpainting a Scene"));
+}
+//! [0]
+
+//! [1]
+GLWidget::~GLWidget()
+{
+}
+//! [1]
+
+static void qNormalizeAngle(int &angle)
+{
+    while (angle < 0)
+        angle += 360 * 16;
+    while (angle > 360 * 16)
+        angle -= 360 * 16;
+}
+
+void GLWidget::setXRotation(int angle)
+{
+    qNormalizeAngle(angle);
+    if (angle != xRot)
+        xRot = angle;
+}
+
+void GLWidget::setYRotation(int angle)
+{
+    qNormalizeAngle(angle);
+    if (angle != yRot)
+        yRot = angle;
+}
+
+void GLWidget::setZRotation(int angle)
+{
+    qNormalizeAngle(angle);
+    if (angle != zRot)
+        zRot = angle;
+}
+
+//! [2]
+void GLWidget::initializeGL()
+{
+    glEnable(GL_MULTISAMPLE);
+
+    logo = new QtLogo(this);
+    logo->setColor(qtGreen.dark());
+}
+//! [2]
+
+void GLWidget::mousePressEvent(QMouseEvent *event)
+{
+    lastPos = event->pos();
+}
+
+void GLWidget::mouseMoveEvent(QMouseEvent *event)
+{
+    int dx = event->x() - lastPos.x();
+    int dy = event->y() - lastPos.y();
+
+    if (event->buttons() & Qt::LeftButton) {
+        setXRotation(xRot + 8 * dy);
+        setYRotation(yRot + 8 * dx);
+    } else if (event->buttons() & Qt::RightButton) {
+        setXRotation(xRot + 8 * dy);
+        setZRotation(zRot + 8 * dx);
+    }
+    lastPos = event->pos();
+}
+
+void GLWidget::paintEvent(QPaintEvent *event)
+{
+    makeCurrent();
+//! [4]
+    glMatrixMode(GL_MODELVIEW);
+    glPushMatrix();
+//! [4]
+
+//! [6]
+    qglClearColor(qtPurple.dark());
+    glShadeModel(GL_SMOOTH);
+    glEnable(GL_DEPTH_TEST);
+    glEnable(GL_CULL_FACE);
+    glEnable(GL_LIGHTING);
+    glEnable(GL_LIGHT0);
+    glEnable(GL_MULTISAMPLE);
+    static GLfloat lightPosition[4] = { 0.5, 5.0, 7.0, 1.0 };
+    glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
+
+    qreal pixelRatio = devicePixelRatio();
+    setupViewport(width() * pixelRatio, height() * pixelRatio);
+//! [6]
+
+//! [7]
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    glLoadIdentity();
+    glTranslatef(0.0, 0.0, -10.0);
+    glRotatef(xRot / 16.0, 1.0, 0.0, 0.0);
+    glRotatef(yRot / 16.0, 0.0, 1.0, 0.0);
+    glRotatef(zRot / 16.0, 0.0, 0.0, 1.0);
+
+    logo->draw();
+//! [7]
+
+//! [8]
+    glShadeModel(GL_FLAT);
+    glDisable(GL_CULL_FACE);
+    glDisable(GL_DEPTH_TEST);
+    glDisable(GL_LIGHTING);
+
+    glMatrixMode(GL_MODELVIEW);
+    glPopMatrix();
+//! [8]
+
+//! [10]
+    QPainter painter(this);
+    painter.setRenderHint(QPainter::Antialiasing);
+    foreach (Bubble *bubble, bubbles) {
+        if (bubble->rect().intersects(event->rect()))
+            bubble->drawBubble(&painter);
+    }
+    drawInstructions(&painter);
+    painter.end();
+}
+//! [10]
+
+//! [11]
+void GLWidget::resizeGL(int width, int height)
+{
+    qreal pixelRatio = devicePixelRatio();
+    setupViewport(width*pixelRatio, height*pixelRatio);
+}
+//! [11]
+
+//! [12]
+void GLWidget::showEvent(QShowEvent *event)
+{
+    Q_UNUSED(event);
+    createBubbles(20 - bubbles.count());
+}
+//! [12]
+
+QSize GLWidget::sizeHint() const
+{
+    return QSize(400, 400);
+}
+
+void GLWidget::createBubbles(int number)
+{
+    for (int i = 0; i < number; ++i) {
+        QPointF position(width()*(0.1 + (0.8*qrand()/(RAND_MAX+1.0))),
+                        height()*(0.1 + (0.8*qrand()/(RAND_MAX+1.0))));
+        qreal radius = qMin(width(), height())*(0.0125 + 0.0875*qrand()/(RAND_MAX+1.0));
+        QPointF velocity(width()*0.0125*(-0.5 + qrand()/(RAND_MAX+1.0)),
+                        height()*0.0125*(-0.5 + qrand()/(RAND_MAX+1.0)));
+
+        bubbles.append(new Bubble(position, radius, velocity));
+    }
+}
+
+//! [13]
+void GLWidget::animate()
+{
+    QMutableListIterator<Bubble*> iter(bubbles);
+
+    while (iter.hasNext()) {
+        Bubble *bubble = iter.next();
+        bubble->move(rect());
+    }
+    update();
+}
+//! [13]
+
+//! [14]
+void GLWidget::setupViewport(int width, int height)
+{
+    int side = qMin(width, height);
+    glViewport((width - side) / 2, (height - side) / 2, side, side);
+
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();
+#ifdef QT_OPENGL_ES
+    glOrthof(-0.5, +0.5, -0.5, 0.5, 4.0, 15.0);
+#else
+    glOrtho(-0.5, +0.5, -0.5, 0.5, 4.0, 15.0);
+#endif
+    glMatrixMode(GL_MODELVIEW);
+}
+//! [14]
+
+//! [15]
+void GLWidget::drawInstructions(QPainter *painter)
+{
+    QString text = tr("Click and drag with the left mouse button "
+                      "to rotate the Qt logo.");
+    QFontMetrics metrics = QFontMetrics(font());
+    int border = qMax(4, metrics.leading());
+
+    QRect rect = metrics.boundingRect(0, 0, width() - 2*border, int(height()*0.125),
+                                      Qt::AlignCenter | Qt::TextWordWrap, text);
+    painter->setRenderHint(QPainter::TextAntialiasing);
+    painter->fillRect(QRect(0, 0, width(), rect.height() + 2*border),
+                     QColor(0, 0, 0, 127));
+    painter->setPen(Qt::white);
+    painter->fillRect(QRect(0, 0, width(), rect.height() + 2*border),
+                      QColor(0, 0, 0, 127));
+    painter->drawText((width() - rect.width())/2, border,
+                      rect.width(), rect.height(),
+                      Qt::AlignCenter | Qt::TextWordWrap, text);
+}
+//! [15]