/****************************************************************************

**

** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

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** This file is part of the demonstration applications of the Qt Toolkit.

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** contained in the Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

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** 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

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****************************************************************************/

//#include <GL/glew.h>

#include "glextensions.h"

#include "scene.h"

#include <QtGui>

#include <QGLWidget>

class GraphicsView : public QGraphicsView

{

public:

    GraphicsView()

    {

        setWindowTitle(tr("Boxes"));

        setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);

        //setRenderHints(QPainter::SmoothPixmapTransform);

    }

protected:

    void resizeEvent(QResizeEvent *event) {

        if (scene())

            scene()->setSceneRect(QRect(QPoint(0, 0), event->size()));

        QGraphicsView::resizeEvent(event);

    }

};

inline bool matchString(const char *extensionString, const char *subString)

{

    int subStringLength = strlen(subString);

    return (strncmp(extensionString, subString, subStringLength) == 0)

        && ((extensionString[subStringLength] == ' ') || (extensionString[subStringLength] == '\0'));

}

bool necessaryExtensionsSupported()

{

    const char *extensionString = reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS));

    const char *p = extensionString;

    const int GL_EXT_FBO = 1;

    const int GL_ARB_VS = 2;

    const int GL_ARB_FS = 4;

    const int GL_ARB_SO = 8;

    int extensions = 0;

    while (*p) {

        if (matchString(p, "GL_EXT_framebuffer_object"))

            extensions |= GL_EXT_FBO;

        else if (matchString(p, "GL_ARB_vertex_shader"))

            extensions |= GL_ARB_VS;

        else if (matchString(p, "GL_ARB_fragment_shader"))

            extensions |= GL_ARB_FS;

        else if (matchString(p, "GL_ARB_shader_objects"))

            extensions |= GL_ARB_SO;

        while ((*p != ' ') && (*p != '\0'))

            ++p;

        if (*p == ' ')

            ++p;

    }

    return (extensions == 15);

}

int main(int argc, char **argv)

{

    QApplication app(argc, argv);

    if ((QGLFormat::openGLVersionFlags() & QGLFormat::OpenGL_Version_1_5) == 0) {

        QMessageBox::critical(0, "OpenGL features missing",

            "OpenGL version 1.5 or higher is required to run this demo.\n"

            "The program will now exit.");

        return -1;

    }

    int maxTextureSize = 1024;

    QGLWidget *widget = new QGLWidget(QGLFormat(QGL::SampleBuffers));

    widget->makeCurrent();

    if (!necessaryExtensionsSupported()) {

        QMessageBox::critical(0, "OpenGL features missing",

            "The OpenGL extensions required to run this demo are missing.\n"

            "The program will now exit.");

        delete widget;

        return -2;

    }

    // Check if all the necessary functions are resolved.

    if (!getGLExtensionFunctions().resolve(widget->context())) {

        QMessageBox::critical(0, "OpenGL features missing",

            "Failed to resolve OpenGL functions required to run this demo.\n"

            "The program will now exit.");

        delete widget;

        return -3;

    }

    // TODO: Make conditional for final release

    QMessageBox::information(0, "For your information",

        "This demo can be GPU and CPU intensive and may\n"

        "work poorly or not at all on your system.");

    widget->makeCurrent(); // The current context must be set before calling Scene's constructor

    Scene scene(1024, 768, maxTextureSize);

    GraphicsView view;

    view.setViewport(widget);

    view.setViewportUpdateMode(QGraphicsView::FullViewportUpdate);

    view.setScene(&scene);

    view.show();

    return app.exec();

}