Three scene graph examples with docs.

How to make a custom QSGGeometry, how to use QSGSimpleMaterial and how
to use render with raw GL.

Change-Id: I3e5a32b6ae12d7d781c11050ed26a54845e92cca
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>

5 files changed, 385 insertions, 0 deletions

diff --git a/examples/quick/scenegraph/openglunderqml/main.cpp b/examples/quick/scenegraph/openglunderqml/main.cpp
new file mode 100644
index 0000000000..223f8bf360
--- /dev/null
+++ b/examples/quick/scenegraph/openglunderqml/main.cpp
@@ -0,0 +1,61 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QGuiApplication>
+
+#include <QtQuick/QQuickView>
+
+#include "squircle.h"
+
+//! [1]
+int main(int argc, char **argv)
+{
+    QGuiApplication app(argc, argv);
+
+    qmlRegisterType<Squircle>("OpenGLUnderQML", 1, 0, "Squircle");
+
+    QQuickView view;
+    view.setSource(QUrl("main.qml"));
+    view.show();
+
+    return app.exec();
+}
+//! [1]
diff --git a/examples/quick/scenegraph/openglunderqml/main.qml b/examples/quick/scenegraph/openglunderqml/main.qml
new file mode 100644
index 0000000000..1823d2a7b6
--- /dev/null
+++ b/examples/quick/scenegraph/openglunderqml/main.qml
@@ -0,0 +1,80 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//! [1]
+import QtQuick 2.0
+import OpenGLUnderQML 1.0
+
+Item {
+
+    width: 320
+    height: 480
+
+    Squircle {
+        SequentialAnimation on t {
+            NumberAnimation { to: 1; duration: 2500; easing.type: Easing.InQuad }
+            NumberAnimation { to: 0; duration: 2500; easing.type: Easing.OutQuad }
+            loops: Animation.Infinite
+            running: true
+        }
+    }
+//! [1] //! [2]
+    Rectangle {
+        color: Qt.rgba(1, 1, 1, 0.7)
+        radius: 10
+        border.width: 1
+        border.color: "white"
+        anchors.fill: label
+        anchors.margins: -10
+    }
+
+    Text {
+        id: label
+        color: "black"
+        wrapMode: Text.WordWrap
+        text: "The background here is a squircle rendered with raw OpenGL using the 'beforeRender()' signal in QQuickWindow. This text label and its border is rendered using QML"
+        anchors.right: parent.right
+        anchors.left: parent.left
+        anchors.bottom: parent.bottom
+        anchors.margins: 20
+    }
+}
+//! [2]
diff --git a/examples/quick/scenegraph/openglunderqml/openglunderqml.pro b/examples/quick/scenegraph/openglunderqml/openglunderqml.pro
new file mode 100644
index 0000000000..64a58b3729
--- /dev/null
+++ b/examples/quick/scenegraph/openglunderqml/openglunderqml.pro
@@ -0,0 +1,6 @@
+QT += qml quick
+
+HEADERS += squircle.h
+SOURCES += squircle.cpp main.cpp
+
+OTHER_FILES += main.qml
diff --git a/examples/quick/scenegraph/openglunderqml/squircle.cpp b/examples/quick/scenegraph/openglunderqml/squircle.cpp
new file mode 100644
index 0000000000..f7bbeb9f14
--- /dev/null
+++ b/examples/quick/scenegraph/openglunderqml/squircle.cpp
@@ -0,0 +1,160 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "squircle.h"
+
+#include <QtQuick/qquickwindow.h>
+#include <QtGui/QOpenGLShaderProgram>
+#include <QtGui/QOpenGLContext>
+
+//! [7]
+Squircle::Squircle()
+    : m_program(0)
+{
+}
+//! [7]
+
+//! [8]
+void Squircle::setT(qreal t)
+{
+    if (t == m_t)
+        return;
+    m_t = t;
+    emit tChanged();
+    if (canvas())
+        canvas()->update();
+}
+//! [8]
+
+
+//! [1]
+void Squircle::itemChange(ItemChange change, const ItemChangeData &)
+{
+    // The ItemSceneChange event is sent when we are first attached to a window.
+    if (change == ItemSceneChange) {
+        QQuickWindow *c = window();
+        if (!c)
+            return;
+//! [1]
+
+        // Connect the beforeRendering signal to our paint function.
+        // Since this call is executed on the rendering thread it must be
+        // a Qt::DirectConnection
+//! [2]
+        connect(c, SIGNAL(beforeRendering()), this, SLOT(paint()), Qt::DirectConnection);
+//! [2]
+
+        // If we allow QML to do the clearing, they would clear what we paint
+        // and nothing would show.
+//! [3]
+        c->setClearBeforeRendering(false);
+    }
+}
+//! [3] //! [4]
+void Squircle::paint()
+{
+    if (!m_program) {
+        m_program = new QOpenGLShaderProgram();
+        m_program->addShaderFromSourceCode(QOpenGLShader::Vertex,
+                                           "attribute highp vec4 vertices;"
+                                           "varying highp vec2 coords;"
+                                           "void main() {"
+                                           "    gl_Position = vertices;"
+                                           "    coords = vertices.xy;"
+                                           "}");
+        m_program->addShaderFromSourceCode(QOpenGLShader::Fragment,
+                                           "uniform lowp float t;"
+                                           "varying highp vec2 coords;"
+                                           "void main() {"
+                                           "    lowp float i = 1. - (pow(coords.x, 4.) + pow(coords.y, 4.));"
+                                           "    i = smoothstep(t - 0.8, t + 0.8, i);"
+                                           "    i = floor(i * 20.) / 20.;"
+                                           "    gl_FragColor = vec4(coords * .5 + .5, i, i);"
+                                           "}");
+
+        m_program->bindAttributeLocation("vertices", 0);
+        m_program->link();
+
+        connect(canvas()->openglContext(), SIGNAL(aboutToBeDestroyed()),
+                this, SLOT(cleanup()), Qt::DirectConnection);
+    }
+//! [4] //! [5]
+    m_program->bind();
+
+    m_program->enableAttributeArray(0);
+
+    float values[] = {
+        -1, -1,
+        1, -1,
+        -1, 1,
+        1, 1
+    };
+    m_program->setAttributeArray(0, GL_FLOAT, values, 2);
+    m_program->setUniformValue("t", (float) m_t);
+
+    glViewport(0, 0, window()->width(), window()->height());
+
+    glDisable(GL_DEPTH_TEST);
+
+    glClearColor(0, 0, 0, 1);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE);
+
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+    m_program->disableAttributeArray(0);
+    m_program->release();
+}
+//! [5]
+
+//! [6]
+void Squircle::cleanup()
+{
+    if (m_program) {
+        delete m_program;
+        m_program = 0;
+    }
+}
+//! [6]
+
+
diff --git a/examples/quick/scenegraph/openglunderqml/squircle.h b/examples/quick/scenegraph/openglunderqml/squircle.h
new file mode 100644
index 0000000000..43b002256c
--- /dev/null
+++ b/examples/quick/scenegraph/openglunderqml/squircle.h
@@ -0,0 +1,78 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef SQUIRCLE_H
+#define SQUIRCLE_H
+
+#include <QtQuick/QQuickItem>
+#include <QtGui/QOpenGLShaderProgram>
+
+//! [1]
+class Squircle : public QQuickItem
+{
+    Q_OBJECT
+
+    Q_PROPERTY(qreal t READ t WRITE setT NOTIFY tChanged)
+
+public:
+    Squircle();
+
+    qreal t() const { return m_t; }
+    void setT(qreal t);
+
+signals:
+    void tChanged();
+
+protected:
+    void itemChange(ItemChange change, const ItemChangeData &);
+
+public slots:
+    void paint();
+    void cleanup();
+
+private:
+    QOpenGLShaderProgram *m_program;
+
+    qreal m_t;
+};
+//! [1]
+
+#endif // SQUIRCLE_H