class Horde3DViewport : public QDeclarativeItem
{
    Q_OBJECT
public:
    Horde3DViewport(QDeclarativeItem *parent)
        : QDeclarativeItem(parent), m_initialized(false), m_animation(this)
    {
        setFlag(QGraphicsItem::ItemHasNoContents, false);
        // XXX: start redraw animation (a timer, that calls QDeclarativeItem::update()).
    }

    ~Horde3DViewport()
    {
        // XXX: destroy scene and release Horde3D.
    }
       
protected:
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
    {
        Q_UNUSED(option);
        QPaintEngine::Type engineType = painter->paintEngine()->type();
        if (engineType == QPaintEngine::OpenGL || engineType == QPaintEngine::OpenGL2) {
            painter->beginNativePainting();
            // Initialize.
            if (!m_initialized) {
                // XXX: initialize Horde3D and create a scene
                m_initialized = true;
            }
            // Render.
            h3dRender(m_camera);
            h3dFinalizeFrame();
            // Restore render state.
            glBindBuffer(GL_ARRAY_BUFFER, 0);
            glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
            glBindRenderbuffer(GL_RENDERBUFFER, 0);
            glBindFramebuffer(GL_FRAMEBUFFER_EXT, 0);
            painter->endNativePainting();
        }
    }
   

private:
    // XXX: Pipeline, etc.
    H3DNode m_camera;
};

#ifndef HORDEVIEWPORT_H
#define HORDEVIEWPORT_H

#include <QtDeclarative/QDeclarativeItem>
#include <QtCore/QBasicTimer>
#include <Horde3D.h>

class QGLFramebufferObject;
class HordeViewport;

class HordeViewportAnimation : public QAbstractAnimation
{
    Q_OBJECT
public:
    HordeViewportAnimation(HordeViewport *parent = 0);
    ~HordeViewportAnimation();

    int duration() const;

protected:
    void updateCurrentTime(int currentTime);

private:
    HordeViewport* m_viewport;
};

class HordeViewport : public QDeclarativeItem
{
    Q_OBJECT
public:
    HordeViewport(QDeclarativeItem *parent = 0);
    ~HordeViewport();

protected:
    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry);
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);

private:
    void validateGL(int deviceWidth, int deviceHeight);
    void paintGL();

   bool m_firstRun;
    bool m_valid;
    QGLFramebufferObject *m_fbo;
    HordeViewportAnimation m_animation;
    H3DNode m_camera;
};

QML_DECLARE_TYPE(HordeViewport)

#endif

#include "hordeviewport.h"
#include <QGLFramebufferObject>

HordeViewportAnimation::HordeViewportAnimation(HordeViewport *parent)
    : QAbstractAnimation(parent), m_viewport(parent)
{
    // Do nothing.
}

HordeViewportAnimation::~HordeViewportAnimation()
{
    // Do nothing.
}

int HordeViewportAnimation::duration() const
{
    // Duration is undefined (infinite).
    return -1;
}

void HordeViewportAnimation::updateCurrentTime(int currentTime)
{
    // Schedule redraw.
    m_viewport->update();
}

HordeViewport::HordeViewport(QDeclarativeItem *parent)
    : QDeclarativeItem(parent), m_firstRun(true), m_valid(false),
      m_fbo(0), m_animation(this), m_camera(0)
{
    setFlag(QGraphicsItem::ItemHasNoContents, false);
    m_animation.start();
}

HordeViewport::~HordeViewport()
{
    h3dRelease();
    m_animation.stop();
    if (m_fbo) {
        delete m_fbo;
    }
}

void HordeViewport::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    Q_UNUSED(option);
    QPaintEngine::Type engineType = painter->paintEngine()->type();
    if (engineType == QPaintEngine::OpenGL || engineType == QPaintEngine::OpenGL2) {
        painter->beginNativePainting();
        // Validate if required.
        if (!m_valid) {
            validateGL(painter->device()->width(),
                       painter->device()->height());
            m_valid = true;
        }
        // Render to FBO.
        m_fbo->bind();
        paintGL();
        m_fbo->release();
        // Render FBO to quad.
        glEnable(GL_TEXTURE_2D);
        m_fbo->drawTexture(QPointF(0, 0), m_fbo->texture());
        painter->endNativePainting();
    }
}

void HordeViewport::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    QDeclarativeItem::geometryChanged(newGeometry, oldGeometry);
    m_valid = false;
}

void HordeViewport::validateGL(int deviceWidth, int deviceHeight)
{
   if (m_firstRun) {
      if (!h3dInit()) {
         qCritical() << "h3dInit failed";
      }
      // XXX: other init code
        m_firstRun = false;
   }
    if (m_fbo) {
        delete m_fbo;
    }
    m_fbo = new QGLFramebufferObject(deviceWidth, deviceHeight);
    if (m_camera) {
        // Resize viewport
        h3dSetNodeParamI(m_camera, H3DCamera::ViewportXI, 0);
        h3dSetNodeParamI(m_camera, H3DCamera::ViewportYI, 0);
        h3dSetNodeParamI(m_camera, H3DCamera::ViewportWidthI, deviceWidth);
        h3dSetNodeParamI(m_camera, H3DCamera::ViewportHeightI, deviceHeight);
        // Set virtual camera parameters
        float aspectRatio = static_cast<float>(deviceWidth) / deviceHeight;
        h3dSetupCameraView(m_camera, 45.0f, aspectRatio, 0.1f, 1000.0f);
        H3DRes cameraPipeRes = h3dGetNodeParamI(m_camera, H3DCamera::PipeResI);
        h3dResizePipelineBuffers(cameraPipeRes, deviceWidth, deviceHeight);
    }
}

void HordeViewport::paintGL()
{
    if (...camera changed...) {
        m_camera = // XXX: get camera.
        m_valid = false;
    }
    // XXX: Update scene.
    // Render scene.
    if (m_camera) {
        // Render.
        h3dRender(m_camera);
        h3dFinalizeFrame();
        // Restore render state.
        glDisable(GL_CULL_FACE);
        glDisable(GL_DEPTH_TEST);
    }
}

QDeclarativeView *m_view
qmlRegisterType<HordeViewport>("HordeComponents", 1, 0, "HordeViewport");
// Setup view.
m_view->setViewport(new QGLWidget(QGLFormat::defaultFormat()));
m_view->setRenderHint(QPainter::SmoothPixmapTransform);
m_view->setRenderHint(QPainter::Antialiasing);
m_view->setResizeMode(QDeclarativeView::SizeRootObjectToView);