/********************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

Copyright (C) 2006 Lubos Lunak <l.lunak@kde.org>
Copyright (C) 2009, 2010, 2011 Martin Gräßlin <mgraesslin@kde.org>

Based on glcompmgr code by Felix Bellaby.
Using code from Compiz and Beryl.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/


/*
 This is the OpenGL-based compositing code. It is the primary and most powerful
 compositing backend.

Sources and other compositing managers:
=======================================

- http://opengl.org
    - documentation
        - OpenGL Redbook (http://opengl.org/documentation/red_book/ - note it's only version 1.1)
        - GLX docs (http://opengl.org/documentation/specs/glx/glx1.4.pdf)
        - extensions docs (http://www.opengl.org/registry/)

- glcompmgr
    - http://lists.freedesktop.org/archives/xorg/2006-July/017006.html ,
    - http://www.mail-archive.com/compiz%40lists.freedesktop.org/msg00023.html
    - simple and easy to understand
    - works even without texture_from_pixmap extension
    - claims to support several different gfx cards
    - compile with something like
      "gcc -Wall glcompmgr-0.5.c `pkg-config --cflags --libs glib-2.0` -lGL -lXcomposite -lXdamage -L/usr/X11R6/lib"

- compiz
    - git clone git://anongit.freedesktop.org/git/xorg/app/compiz
    - the ultimate <whatever>
    - glxcompmgr
        - git clone git://anongit.freedesktop.org/git/xorg/app/glxcompgr
        - a rather old version of compiz, but also simpler and as such simpler
            to understand

- beryl
    - a fork of Compiz
    - http://beryl-project.org
    - git clone git://anongit.beryl-project.org/beryl/beryl-core (or beryl-plugins etc. ,
        the full list should be at git://anongit.beryl-project.org/beryl/)

- libcm (metacity)
    - cvs -d :pserver:anonymous@anoncvs.gnome.org:/cvs/gnome co libcm
    - not much idea about it, the model differs a lot from KWin/Compiz/Beryl
    - does not seem to be very powerful or with that much development going on

*/

#include "scene_opengl.h"
#ifdef KWIN_HAVE_EGL
#include "eglonxbackend.h"
#endif
#ifndef KWIN_HAVE_OPENGLES
#include "glxbackend.h"
#endif

#include <kxerrorhandler.h>

#include <kwinglcolorcorrection.h>
#include <kwinglplatform.h>

#include "utils.h"
#include "client.h"
#include "composite.h"
#include "deleted.h"
#include "effects.h"
#include "lanczosfilter.h"
#include "overlaywindow.h"
#include "paintredirector.h"

#include <math.h>

// turns on checks for opengl errors in various places (for easier finding of them)
// normally only few of them are enabled
//#define CHECK_GL_ERROR

#include <X11/extensions/Xcomposite.h>

#include <qpainter.h>
#include <QDesktopWidget>
#include <QVector2D>
#include <QVector4D>
#include <QMatrix4x4>

namespace KWin
{

extern int currentRefreshRate();

//****************************************
// SceneOpenGL
//****************************************
OpenGLBackend::OpenGLBackend()
    : m_overlayWindow(new OverlayWindow()) // TODO: maybe create only if needed?
    , m_waitSync(false)
    , m_directRendering(false)
    , m_doubleBuffer(false)
    , m_failed(false)
    , m_lastMask(0)
{
}

OpenGLBackend::~OpenGLBackend()
{
    if (isFailed()) {
        m_overlayWindow->destroy();
    }
    delete m_overlayWindow;
}

void OpenGLBackend::setFailed(const QString &reason)
{
    kWarning(1212) << "Creating the OpenGL rendering failed: " << reason;
    m_failed = true;
}

void OpenGLBackend::idle()
{
    present();
}

/************************************************
 * SceneOpenGL
 ***********************************************/

SceneOpenGL::SceneOpenGL(Workspace* ws, OpenGLBackend *backend)
    : Scene(ws)
    , init_ok(false)
    , m_backend(backend)
{
    if (m_backend->isFailed()) {
        return;
    }

    // perform Scene specific checks
    GLPlatform *glPlatform = GLPlatform::instance();
#ifndef KWIN_HAVE_OPENGLES
    if (!hasGLExtension("GL_ARB_texture_non_power_of_two")
            && !hasGLExtension("GL_ARB_texture_rectangle")) {
        kError(1212) << "GL_ARB_texture_non_power_of_two and GL_ARB_texture_rectangle missing";
        return; // error
    }
#endif
    if (glPlatform->isMesaDriver() && glPlatform->mesaVersion() < kVersionNumber(8, 0)) {
        kError(1212) << "KWin requires at least Mesa 8.0 for OpenGL compositing.";
        return;
    }
#ifndef KWIN_HAVE_OPENGLES
    if (m_backend->isDoubleBuffer())
        glDrawBuffer(GL_BACK);
#endif

    debug = qstrcmp(qgetenv("KWIN_GL_DEBUG"), "1") == 0;

    // set strict binding
    if (options->isGlStrictBindingFollowsDriver()) {
        options->setGlStrictBinding(!glPlatform->supports(LooseBinding));
    }
}

SceneOpenGL::~SceneOpenGL()
{
    if (init_ok) {
        // backend might be still needed for a different scene
        delete m_backend;
    }
    foreach (Window * w, windows) {
        delete w;
    }
    // do cleanup after initBuffer()
    SceneOpenGL::EffectFrame::cleanup();
    checkGLError("Cleanup");
}

SceneOpenGL *SceneOpenGL::createScene()
{
    OpenGLBackend *backend = NULL;
    OpenGLPlatformInterface platformInterface = NoOpenGLPlatformInterface;
    // should we use glx?
#ifndef KWIN_HAVE_OPENGLES
    // on OpenGL we default to glx
    platformInterface = GlxPlatformInterface;
#endif

#ifdef KWIN_HAVE_EGL
#ifdef KWIN_HAVE_OPENGLES
    // for OpenGL ES we need to use the Egl Backend
    platformInterface = EglPlatformInterface;
#else
    // check environment variable
    if (qstrcmp(qgetenv("KWIN_OPENGL_INTERFACE"), "egl") == 0) {
        kDebug(1212) << "Forcing EGL native interface through environment variable";
        platformInterface = EglPlatformInterface;
    }
#endif
#endif

    switch (platformInterface) {
    case GlxPlatformInterface:
#ifndef KWIN_HAVE_OPENGLES
        backend = new GlxBackend();
#endif
        break;
    case EglPlatformInterface:
#ifdef KWIN_HAVE_EGL
        backend = new EglOnXBackend();
#endif
        break;
    default:
        // no backend available
        return NULL;
    }
    if (!backend || backend->isFailed()) {
        delete backend;
        return NULL;
    }
    SceneOpenGL *scene = NULL;
    // first let's try an OpenGL 2 scene
    if (SceneOpenGL2::supported(backend)) {
        scene = new SceneOpenGL2(backend);
        if (scene->initFailed()) {
            delete scene;
            scene = NULL;
        } else {
            return scene;
        }
    }
#ifdef KWIN_HAVE_OPENGL_1
    if (SceneOpenGL1::supported(backend)) {
        scene = new SceneOpenGL1(backend);
        if (scene->initFailed()) {
            delete scene;
            scene = NULL;
        }
    }
#endif
    if (!scene) {
        if (GLPlatform::instance()->recommendedCompositor() == XRenderCompositing) {
            kError(1212) << "OpenGL driver recommends XRender based compositing. Falling back to XRender.";
            kError(1212) << "To overwrite the detection use the environment variable KWIN_COMPOSE";
            kError(1212) << "For more information see http://community.kde.org/KWin/Environment_Variables#KWIN_COMPOSE";
            QTimer::singleShot(0, Compositor::self(), SLOT(fallbackToXRenderCompositing()));
        }
        delete backend;
    }

    return scene;
}

OverlayWindow *SceneOpenGL::overlayWindow()
{
    return m_backend->overlayWindow();
}

bool SceneOpenGL::waitSyncAvailable() const
{
    return m_backend->waitSyncAvailable();
}

void SceneOpenGL::idle()
{
    m_backend->idle();
    Scene::idle();
}

bool SceneOpenGL::initFailed() const
{
    return !init_ok;
}

int SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
{
    // actually paint the frame, flushed with the NEXT frame
    foreach (Toplevel * c, toplevels) {
        // TODO: cache the stacking_order in case it has not changed
        assert(windows.contains(c));
        stacking_order.append(windows[ c ]);
    }

    m_backend->prepareRenderingFrame();
    int mask = 0;
#ifdef CHECK_GL_ERROR
    checkGLError("Paint1");
#endif
    paintScreen(&mask, &damage);   // call generic implementation
#ifdef CHECK_GL_ERROR
    checkGLError("Paint2");
#endif

    m_backend->endRenderingFrame(mask, damage);

    // do cleanup
    stacking_order.clear();
    checkGLError("PostPaint");
    return m_backend->renderTime();
}

QMatrix4x4 SceneOpenGL::transformation(int mask, const ScreenPaintData &data) const
{
    QMatrix4x4 matrix;

    if (!(mask & PAINT_SCREEN_TRANSFORMED))
        return matrix;

    matrix.translate(data.translation());
    data.scale().applyTo(&matrix);

    if (data.rotationAngle() == 0.0)
        return matrix;

    // Apply the rotation
    // cannot use data.rotation->applyTo(&matrix) as QGraphicsRotation uses projectedRotate to map back to 2D
    matrix.translate(data.rotationOrigin());
    const QVector3D axis = data.rotationAxis();
    matrix.rotate(data.rotationAngle(), axis.x(), axis.y(), axis.z());
    matrix.translate(-data.rotationOrigin());

    return matrix;
}

void SceneOpenGL::paintBackground(QRegion region)
{
    PaintClipper pc(region);
    if (!PaintClipper::clip()) {
        glClearColor(0, 0, 0, 1);
        glClear(GL_COLOR_BUFFER_BIT);
        return;
    }
    if (pc.clip() && pc.paintArea().isEmpty())
        return; // no background to paint
    QVector<float> verts;
    for (PaintClipper::Iterator iterator; !iterator.isDone(); iterator.next()) {
        QRect r = iterator.boundingRect();
        verts << r.x() + r.width() << r.y();
        verts << r.x() << r.y();
        verts << r.x() << r.y() + r.height();
        verts << r.x() << r.y() + r.height();
        verts << r.x() + r.width() << r.y() + r.height();
        verts << r.x() + r.width() << r.y();
    }
    doPaintBackground(verts);
}

void SceneOpenGL::windowAdded(Toplevel* c)
{
    assert(!windows.contains(c));
    Window *w = createWindow(c);
    windows[ c ] = w;
    w->setScene(this);
    connect(c, SIGNAL(opacityChanged(KWin::Toplevel*,qreal)), SLOT(windowOpacityChanged(KWin::Toplevel*)));
    connect(c, SIGNAL(geometryShapeChanged(KWin::Toplevel*,QRect)), SLOT(windowGeometryShapeChanged(KWin::Toplevel*)));
    connect(c, SIGNAL(windowClosed(KWin::Toplevel*,KWin::Deleted*)), SLOT(windowClosed(KWin::Toplevel*,KWin::Deleted*)));
    c->effectWindow()->setSceneWindow(windows[ c ]);
    c->getShadow();
    windows[ c ]->updateShadow(c->shadow());
}

void SceneOpenGL::windowClosed(KWin::Toplevel* c, KWin::Deleted* deleted)
{
    assert(windows.contains(c));
    if (deleted != NULL) {
        // replace c with deleted
        Window* w = windows.take(c);
        w->updateToplevel(deleted);
        if (w->shadow()) {
            w->shadow()->setToplevel(deleted);
        }
        windows[ deleted ] = w;
    } else {
        delete windows.take(c);
        c->effectWindow()->setSceneWindow(NULL);
    }
}

void SceneOpenGL::windowDeleted(Deleted* c)
{
    assert(windows.contains(c));
    delete windows.take(c);
    c->effectWindow()->setSceneWindow(NULL);
}

void SceneOpenGL::windowGeometryShapeChanged(KWin::Toplevel* c)
{
    if (!windows.contains(c))    // this is ok, shape is not valid
        return;                 // by default
    Window* w = windows[ c ];
    w->discardShape();
    w->checkTextureSize();
}

void SceneOpenGL::windowOpacityChanged(KWin::Toplevel* t)
{
    Q_UNUSED(t)
#if 0 // not really needed, windows are painted on every repaint
    // and opacity is used when applying texture, not when
    // creating it
    if (!windows.contains(c))    // this is ok, texture is created
        return;                 // on demand
    Window* w = windows[ c ];
    w->discardTexture();
#endif
}

SceneOpenGL::Texture *SceneOpenGL::createTexture()
{
    return new Texture(m_backend);
}

SceneOpenGL::Texture *SceneOpenGL::createTexture(const QPixmap &pix, GLenum target)
{
    return new Texture(m_backend, pix, target);
}

void SceneOpenGL::screenGeometryChanged(const QSize &size)
{
    Scene::screenGeometryChanged(size);
    glViewport(0,0, size.width(), size.height());
    m_backend->screenGeometryChanged(size);
    ShaderManager::instance()->resetAllShaders();
}

//****************************************
// SceneOpenGL2
//****************************************
bool SceneOpenGL2::supported(OpenGLBackend *backend)
{
    const QByteArray forceEnv = qgetenv("KWIN_COMPOSE");
    if (!forceEnv.isEmpty()) {
        if (qstrcmp(forceEnv, "O2") == 0) {
            kDebug(1212) << "OpenGL 2 compositing enforced by environment variable";
            return true;
        } else {
            // OpenGL 2 disabled by environment variable
            return false;
        }
    }
    if (!backend->isDirectRendering()) {
        return false;
    }
    if (GLPlatform::instance()->recommendedCompositor() < OpenGL2Compositing) {
        kDebug(1212) << "Driver does not recommend OpenGL 2 compositing";
        return false;
    }
    if (options->isGlLegacy()) {
        kDebug(1212) << "OpenGL 2 disabled by config option";
        return false;
    }
    return true;
}

SceneOpenGL2::SceneOpenGL2(OpenGLBackend *backend)
    : SceneOpenGL(Workspace::self(), backend)
    , m_colorCorrection(new ColorCorrection(this))
{
    // Initialize color correction before the shaders
    kDebug(1212) << "Color correction:" << options->isColorCorrected();
    m_colorCorrection->setEnabled(options->isColorCorrected());
    connect(m_colorCorrection, SIGNAL(changed()), Compositor::self(), SLOT(addRepaintFull()));
    connect(options, SIGNAL(colorCorrectedChanged()), this, SLOT(slotColorCorrectedChanged()));

    if (!ShaderManager::instance()->isValid()) {
        kDebug(1212) << "No Scene Shaders available";
        return;
    }

    // push one shader on the stack so that one is always bound
    ShaderManager::instance()->pushShader(ShaderManager::SimpleShader);
    if (checkGLError("Init")) {
        kError(1212) << "OpenGL 2 compositing setup failed";
        return; // error
    }
    kDebug(1212) << "OpenGL 2 compositing successfully initialized";

    init_ok = true;
}

SceneOpenGL2::~SceneOpenGL2()
{
}

void SceneOpenGL2::paintGenericScreen(int mask, ScreenPaintData data)
{
    ShaderBinder binder(ShaderManager::GenericShader);

    binder.shader()->setUniform(GLShader::ScreenTransformation, transformation(mask, data));

    Scene::paintGenericScreen(mask, data);
}

void SceneOpenGL2::doPaintBackground(const QVector< float >& vertices)
{
    GLVertexBuffer *vbo = GLVertexBuffer::streamingBuffer();
    vbo->reset();
    vbo->setUseColor(true);
    vbo->setData(vertices.count() / 2, 2, vertices.data(), NULL);

    ShaderBinder binder(ShaderManager::ColorShader);
    binder.shader()->setUniform(GLShader::Offset, QVector2D(0, 0));

    vbo->render(GL_TRIANGLES);
}

SceneOpenGL::Window *SceneOpenGL2::createWindow(Toplevel *t)
{
    return new SceneOpenGL2Window(t);
}

void SceneOpenGL2::finalDrawWindow(EffectWindowImpl* w, int mask, QRegion region, WindowPaintData& data)
{
    if (options->isColorCorrected()) {
        // Split the painting for separate screens
        int numScreens = Workspace::self()->numScreens();
        for (int screen = 0; screen < numScreens; ++ screen) {
            QRegion regionForScreen(region);
            if (numScreens > 1)
                regionForScreen = region.intersected(Workspace::self()->screenGeometry(screen));

            data.setScreen(screen);
            performPaintWindow(w, mask, regionForScreen, data);
        }
    } else {
        performPaintWindow(w, mask, region, data);
    }
}

void SceneOpenGL2::performPaintWindow(EffectWindowImpl* w, int mask, QRegion region, WindowPaintData& data)
{
    if (mask & PAINT_WINDOW_LANCZOS) {
        if (m_lanczosFilter.isNull()) {
            m_lanczosFilter = new LanczosFilter(this);
            // recreate the lanczos filter when the screen gets resized
            connect(QApplication::desktop(), SIGNAL(screenCountChanged(int)), m_lanczosFilter.data(), SLOT(deleteLater()));
            connect(QApplication::desktop(), SIGNAL(resized(int)), m_lanczosFilter.data(), SLOT(deleteLater()));
        }
        m_lanczosFilter.data()->performPaint(w, mask, region, data);
    } else
        w->sceneWindow()->performPaint(mask, region, data);
}

ColorCorrection *SceneOpenGL2::colorCorrection()
{
    return m_colorCorrection;
}

void SceneOpenGL2::slotColorCorrectedChanged()
{
    m_colorCorrection->setEnabled(options->isColorCorrected());

    // Reload all shaders
    ShaderManager::cleanup();
    ShaderManager::instance();
}

//****************************************
// SceneOpenGL1
//****************************************
#ifdef KWIN_HAVE_OPENGL_1
bool SceneOpenGL1::supported(OpenGLBackend *backend)
{
    const QByteArray forceEnv = qgetenv("KWIN_COMPOSE");
    if (!forceEnv.isEmpty()) {
        if (qstrcmp(forceEnv, "O1") == 0) {
            kDebug(1212) << "OpenGL 1 compositing enforced by environment variable";
            return true;
        } else {
            // OpenGL 1 disabled by environment variable
            return false;
        }
    }
    if (GLPlatform::instance()->recommendedCompositor() < OpenGL1Compositing) {
        kDebug(1212) << "Driver does not recommend OpenGL 1 compositing";
        return false;
    }
    return true;
}

SceneOpenGL1::SceneOpenGL1(OpenGLBackend *backend)
    : SceneOpenGL(Workspace::self(), backend)
    , m_resetModelViewProjectionMatrix(true)
{
    ShaderManager::disable();
    setupModelViewProjectionMatrix();
    if (checkGLError("Init")) {
        kError(1212) << "OpenGL 1 compositing setup failed";
        return; // error
    }

    kDebug(1212) << "OpenGL 1 compositing successfully initialized";
    init_ok = true;
}

SceneOpenGL1::~SceneOpenGL1()
{
}

int SceneOpenGL1::paint(QRegion damage, ToplevelList windows)
{
    if (m_resetModelViewProjectionMatrix) {
        // reset model view projection matrix if required
        setupModelViewProjectionMatrix();
    }
    return SceneOpenGL::paint(damage, windows);
}

void SceneOpenGL1::paintGenericScreen(int mask, ScreenPaintData data)
{
    pushMatrix(transformation(mask, data));
    Scene::paintGenericScreen(mask, data);
    popMatrix();
}

void SceneOpenGL1::doPaintBackground(const QVector< float >& vertices)
{
    GLVertexBuffer *vbo = GLVertexBuffer::streamingBuffer();
    vbo->reset();
    vbo->setUseColor(true);
    vbo->setData(vertices.count() / 2, 2, vertices.data(), NULL);
    vbo->render(GL_TRIANGLES);
}

void SceneOpenGL1::setupModelViewProjectionMatrix()
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    float fovy = 60.0f;
    float aspect = 1.0f;
    float zNear = 0.1f;
    float zFar = 100.0f;
    float ymax = zNear * tan(fovy  * M_PI / 360.0f);
    float ymin = -ymax;
    float xmin =  ymin * aspect;
    float xmax = ymax * aspect;
    // swap top and bottom to have OpenGL coordinate system match X system
    glFrustum(xmin, xmax, ymin, ymax, zNear, zFar);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    float scaleFactor = 1.1 * tan(fovy * M_PI / 360.0f) / ymax;
    glTranslatef(xmin * scaleFactor, ymax * scaleFactor, -1.1);
    glScalef((xmax - xmin)*scaleFactor / displayWidth(), -(ymax - ymin)*scaleFactor / displayHeight(), 0.001);
    m_resetModelViewProjectionMatrix = false;
}

void SceneOpenGL1::screenGeometryChanged(const QSize &size)
{
    SceneOpenGL::screenGeometryChanged(size);
    m_resetModelViewProjectionMatrix = true;
}

SceneOpenGL::Window *SceneOpenGL1::createWindow(Toplevel *t)
{
    return new SceneOpenGL1Window(t);
}

#endif

//****************************************
// SceneOpenGL::Texture
//****************************************

SceneOpenGL::Texture::Texture(OpenGLBackend *backend)
    : GLTexture(*backend->createBackendTexture(this))
{
}

SceneOpenGL::Texture::Texture(OpenGLBackend *backend, const QPixmap &pix, GLenum target)
    : GLTexture(*backend->createBackendTexture(this))
{
    load(pix, target);
}

SceneOpenGL::Texture::~Texture()
{
}

SceneOpenGL::Texture& SceneOpenGL::Texture::operator = (const SceneOpenGL::Texture& tex)
{
    d_ptr = tex.d_ptr;
    return *this;
}

void SceneOpenGL::Texture::discard()
{
    d_ptr = d_func()->backend()->createBackendTexture(this);
}

bool SceneOpenGL::Texture::load(const Pixmap& pix, const QSize& size,
                                int depth)
{
    if (pix == None)
        return false;
    return load(pix, size, depth,
                QRegion(0, 0, size.width(), size.height()));
}

bool SceneOpenGL::Texture::load(const QImage& image, GLenum target)
{
    if (image.isNull())
        return false;
    return load(QPixmap::fromImage(image), target);
}

bool SceneOpenGL::Texture::load(const QPixmap& pixmap, GLenum target)
{
    if (pixmap.isNull())
        return false;

    // Checking whether QPixmap comes with its own X11 Pixmap
    if (Extensions::nonNativePixmaps()) {
        return GLTexture::load(pixmap.toImage(), target);
    }

    // use the X11 pixmap provided by Qt
    return load(pixmap.handle(), pixmap.size(), pixmap.depth());
}

void SceneOpenGL::Texture::findTarget()
{
    Q_D(Texture);
    d->findTarget();
}

bool SceneOpenGL::Texture::load(const Pixmap& pix, const QSize& size,
                                int depth, QRegion region)
{
    Q_UNUSED(region)
    // decrease the reference counter for the old texture
    d_ptr = d_func()->backend()->createBackendTexture(this); //new TexturePrivate();

    Q_D(Texture);
    return d->loadTexture(pix, size, depth);
}

//****************************************
// SceneOpenGL::Texture
//****************************************
SceneOpenGL::TexturePrivate::TexturePrivate()
{
}

SceneOpenGL::TexturePrivate::~TexturePrivate()
{
}

//****************************************
// SceneOpenGL::Window
//****************************************

SceneOpenGL::Window::Window(Toplevel* c)
    : Scene::Window(c)
    , m_scene(NULL)
    , texture(NULL)
    , topTexture(NULL)
    , leftTexture(NULL)
    , rightTexture(NULL)
    , bottomTexture(NULL)
{
}

SceneOpenGL::Window::~Window()
{
    delete texture;
    delete topTexture;
    delete leftTexture;
    delete rightTexture;
    delete bottomTexture;
}

// Bind the window pixmap to an OpenGL texture.
bool SceneOpenGL::Window::bindTexture()
{
    if (!texture) {
        texture = m_scene->createTexture();
    }
    if (!texture->isNull()) {
        if (!toplevel->damage().isEmpty()) {
            // mipmaps need to be updated
            texture->setDirty();
            toplevel->resetDamage(QRect(toplevel->clientPos(), toplevel->clientSize()));
        }
        return true;
    }
    // Get the pixmap with the window contents
    Pixmap pix = toplevel->windowPixmap();
    if (pix == None)
        return false;

    bool success = texture->load(pix, toplevel->size(), toplevel->depth(),
                                toplevel->damage());

    if (success)
        toplevel->resetDamage(QRect(toplevel->clientPos(), toplevel->clientSize()));
    else
        kDebug(1212) << "Failed to bind window";
    return success;
}

void SceneOpenGL::Window::discardTexture()
{
    if (texture) {
        texture->discard();
    }
    if (!Extensions::nonNativePixmaps()) {
        // only discard if the deco pixmaps use TFP
        if (topTexture) {
            topTexture->discard();
        }
        if (leftTexture) {
            leftTexture->discard();
        }
        if (rightTexture) {
            rightTexture->discard();
        }
        if (bottomTexture) {
            bottomTexture->discard();
        }
    }
}

// This call is used in SceneOpenGL::windowGeometryShapeChanged(),
// which originally called discardTexture(), however this was causing performance
// problems with the launch feedback icon - large number of texture rebinds.
// Since the launch feedback icon does not resize, only changes shape, it
// is not necessary to rebind the texture (with no strict binding), therefore
// discard the texture only if size changes.
void SceneOpenGL::Window::checkTextureSize()
{
    if (!texture) {
        return;
    }
    if (texture->size() != size())
        discardTexture();
}

// when the window's composite pixmap is discarded, undo binding it to the texture
void SceneOpenGL::Window::pixmapDiscarded()
{
    if (!texture) {
        return;
    }
    texture->discard();
}

QMatrix4x4 SceneOpenGL::Window::transformation(int mask, const WindowPaintData &data) const
{
    QMatrix4x4 matrix;
    matrix.translate(x(), y());

    if (!(mask & PAINT_WINDOW_TRANSFORMED))
        return matrix;

    matrix.translate(data.translation());
    data.scale().applyTo(&matrix);

    if (data.rotationAngle() == 0.0)
        return matrix;

    // Apply the rotation
    // cannot use data.rotation.applyTo(&matrix) as QGraphicsRotation uses projectedRotate to map back to 2D
    matrix.translate(data.rotationOrigin());
    const QVector3D axis = data.rotationAxis();
    matrix.rotate(data.rotationAngle(), axis.x(), axis.y(), axis.z());
    matrix.translate(-data.rotationOrigin());

    return matrix;
}

// paint the window
void SceneOpenGL::Window::performPaint(int mask, QRegion region, WindowPaintData data)
{
    if (region.isEmpty())
        return;

    bool hardwareClipping = region != infiniteRegion() && (mask & PAINT_WINDOW_TRANSFORMED);
    if (region != infiniteRegion() && !hardwareClipping) {
        WindowQuadList quads;
        const QRegion filterRegion = region.translated(-x(), -y());
        // split all quads in bounding rect with the actual rects in the region
        foreach (const WindowQuad &quad, data.quads) {
            foreach (const QRect &r, filterRegion.rects()) {
                const QRectF rf(r);
                const QRectF quadRect(QPointF(quad.left(), quad.top()), QPointF(quad.right(), quad.bottom()));
                // case 1: completely contains, include and do not check other rects
                if (rf.contains(quadRect)) {
                    quads << quad;
                    break;
                }
                // case 2: intersection
                if (rf.intersects(quadRect)) {
                    const QRectF intersected = rf.intersected(quadRect);
                    quads << quad.makeSubQuad(intersected.left(), intersected.top(), intersected.right(), intersected.bottom());
                }
            }
        }
        data.quads = quads;
    }

    if (!bindTexture()) {
        return;
    }

    if (hardwareClipping) {
        glEnable(GL_SCISSOR_TEST);
    }

    // Update the texture filter
    if (options->glSmoothScale() != 0 &&
        (mask & (PAINT_WINDOW_TRANSFORMED | PAINT_SCREEN_TRANSFORMED)))
        filter = ImageFilterGood;
    else
        filter = ImageFilterFast;

    texture->setFilter(filter == ImageFilterGood ? GL_LINEAR : GL_NEAREST);

    beginRenderWindow(mask, data);

    GLVertexBuffer *vbo = GLVertexBuffer::streamingBuffer();
    vbo->reset();

    // shadow
    if (m_shadow) {
        paintShadow(region, data, hardwareClipping);
    }
    // decorations
    if (toplevel->isClient()) {
        paintDecorations<Client>(data, region, hardwareClipping);
    } else if (toplevel->isDeleted()) {
        paintDecorations<Deleted>(data, region, hardwareClipping);
    }

    // paint the content
    WindowQuadList contentQuads = data.quads.select(WindowQuadContents);
    if (!contentQuads.empty()) {
        texture->bind();
        prepareStates(Content, data.opacity(), data.brightness(), data.saturation(), data.screen());
        renderQuads(mask, region, contentQuads, texture, false, hardwareClipping);
        restoreStates(Content, data.opacity(), data.brightness(), data.saturation());
        texture->unbind();
#ifndef KWIN_HAVE_OPENGLES
        if (m_scene && m_scene->debug) {
            glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
            renderQuads(mask, region, contentQuads, texture, false, hardwareClipping);
            glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
        }
#endif
    }

    if (hardwareClipping) {
        glDisable(GL_SCISSOR_TEST);
    }

    endRenderWindow(data);
}

template<class T>
void SceneOpenGL::Window::paintDecorations(const WindowPaintData &data, const QRegion &region, bool hardwareClipping)
{
    T* t = static_cast<T*>(toplevel);
    PaintRedirector *redirector = t->decorationPaintRedirector();
    if (t->noBorder() || !redirector) {
        return;
    }
    WindowQuadList decoration = data.quads.select(WindowQuadDecoration);
    QRect topRect, leftRect, rightRect, bottomRect;
    const bool updateDeco = redirector->requiresRepaint();

    t->layoutDecorationRects(leftRect, topRect, rightRect, bottomRect, Client::WindowRelative);

    const QPixmap *left   = redirector->leftDecoPixmap();
    const QPixmap *top    = redirector->topDecoPixmap();
    const QPixmap *right  = redirector->rightDecoPixmap();
    const QPixmap *bottom = redirector->bottomDecoPixmap();

    WindowQuadList topList, leftList, rightList, bottomList;

    foreach (const WindowQuad & quad, decoration) {
        if (topRect.contains(QPoint(quad.originalLeft(), quad.originalTop()))) {
            topList.append(quad);
            continue;
        }
        if (bottomRect.contains(QPoint(quad.originalLeft(), quad.originalTop()))) {
            bottomList.append(quad);
            continue;
        }
        if (leftRect.contains(QPoint(quad.originalLeft(), quad.originalTop()))) {
            leftList.append(quad);
            continue;
        }
        if (rightRect.contains(QPoint(quad.originalLeft(), quad.originalTop()))) {
            rightList.append(quad);
            continue;
        }
    }

    redirector->ensurePixmapsPainted();
    paintDecoration(top, DecorationTop, region, topRect, data, topList, updateDeco, hardwareClipping);
    paintDecoration(left, DecorationLeft, region, leftRect, data, leftList, updateDeco, hardwareClipping);
    paintDecoration(right, DecorationRight, region, rightRect, data, rightList, updateDeco, hardwareClipping);
    paintDecoration(bottom, DecorationBottom, region, bottomRect, data, bottomList, updateDeco, hardwareClipping);

    redirector->markAsRepainted();
}


void SceneOpenGL::Window::paintDecoration(const QPixmap* decoration, TextureType decorationType,
                                          const QRegion& region, const QRect& rect, const WindowPaintData& data,
                                          const WindowQuadList& quads, bool updateDeco, bool hardwareClipping)
{
    SceneOpenGL::Texture* decorationTexture;
    switch(decorationType) {
    case DecorationTop:
        if (!topTexture) {
            topTexture = m_scene->createTexture();
        }
        decorationTexture = topTexture;
        break;
    case DecorationLeft:
        if (!leftTexture) {
            leftTexture = m_scene->createTexture();
        }
        decorationTexture = leftTexture;
        break;
    case DecorationRight:
        if (!rightTexture) {
            rightTexture = m_scene->createTexture();
        }
        decorationTexture = rightTexture;
        break;
    case DecorationBottom:
        if (!bottomTexture) {
            bottomTexture = m_scene->createTexture();
        }
        decorationTexture = bottomTexture;
        break;
    default:
        return;
    }
    if (decoration->isNull() || !decorationTexture) {
        return;
    }
    if (decorationTexture->isNull() || updateDeco) {
        bool success = decorationTexture->load(*decoration);
        if (!success) {
            kDebug(1212) << "Failed to bind decoartion";
            return;
        }
    }

    // We have to update the texture although we do not paint anything.
    // This is especially needed if we draw the opaque part of the window
    // and the decoration in two different passes (as we in Scene::paintSimpleWindow do).
    // Otherwise we run into the situation that in the first pass there are some
    // pending decoration repaints but we don't paint the decoration and in the
    // second pass it's the other way around.
    if (quads.isEmpty())
        return;

    if (filter == ImageFilterGood)
        decorationTexture->setFilter(GL_LINEAR);
    else
        decorationTexture->setFilter(GL_NEAREST);
    decorationTexture->setWrapMode(GL_CLAMP_TO_EDGE);
    decorationTexture->bind();

    prepareStates(decorationType, data.opacity() * data.decorationOpacity(), data.brightness(), data.saturation(), data.screen());
    makeDecorationArrays(quads, rect, decorationTexture);
    GLVertexBuffer::streamingBuffer()->render(region, GL_TRIANGLES, hardwareClipping);
    restoreStates(decorationType, data.opacity() * data.decorationOpacity(), data.brightness(), data.saturation());
    decorationTexture->unbind();
#ifndef KWIN_HAVE_OPENGLES
    if (m_scene && m_scene->debug) {
        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
        GLVertexBuffer::streamingBuffer()->render(region, GL_TRIANGLES, hardwareClipping);
        glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    }
#endif
}

void SceneOpenGL::Window::paintShadow(const QRegion &region, const WindowPaintData &data, bool hardwareClipping)
{
    WindowQuadList quads = data.quads.select(WindowQuadShadowTopLeft);
    quads.append(data.quads.select(WindowQuadShadowTop));
    quads.append(data.quads.select(WindowQuadShadowTopRight));
    quads.append(data.quads.select(WindowQuadShadowRight));
    quads.append(data.quads.select(WindowQuadShadowBottomRight));
    quads.append(data.quads.select(WindowQuadShadowBottom));
    quads.append(data.quads.select(WindowQuadShadowBottomLeft));
    quads.append(data.quads.select(WindowQuadShadowLeft));
    if (quads.isEmpty()) {
        return;
    }
    GLTexture *texture = static_cast<SceneOpenGLShadow*>(m_shadow)->shadowTexture();
    if (!texture) {
        return;
    }
    if (filter == ImageFilterGood)
        texture->setFilter(GL_LINEAR);
    else
        texture->setFilter(GL_NEAREST);
    texture->setWrapMode(GL_CLAMP_TO_EDGE);
    texture->bind();
    prepareStates(Shadow, data.opacity(), data.brightness(), data.saturation(), data.screen());
    renderQuads(0, region, quads, texture, true, hardwareClipping);
    restoreStates(Shadow, data.opacity(), data.brightness(), data.saturation());
    texture->unbind();
#ifndef KWIN_HAVE_OPENGLES
    if (m_scene && m_scene->debug) {
        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
        renderQuads(0, region, quads, texture, true, hardwareClipping);
        glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    }
#endif
}

void SceneOpenGL::Window::makeDecorationArrays(const WindowQuadList& quads, const QRect &rect, Texture *tex) const
{
    QVector<float> vertices;
    QVector<float> texcoords;
    vertices.reserve(quads.count() * 6 * 2);
    texcoords.reserve(quads.count() * 6 * 2);
    float width = rect.width();
    float height = rect.height();
#ifndef KWIN_HAVE_OPENGLES
    if (tex->target() == GL_TEXTURE_RECTANGLE_ARB) {
        width = 1.0;
        height = 1.0;
    }
#endif
    foreach (const WindowQuad & quad, quads) {
        vertices << quad[ 1 ].x();
        vertices << quad[ 1 ].y();
        vertices << quad[ 0 ].x();
        vertices << quad[ 0 ].y();
        vertices << quad[ 3 ].x();
        vertices << quad[ 3 ].y();
        vertices << quad[ 3 ].x();
        vertices << quad[ 3 ].y();
        vertices << quad[ 2 ].x();
        vertices << quad[ 2 ].y();
        vertices << quad[ 1 ].x();
        vertices << quad[ 1 ].y();

        if (tex->isYInverted()) {
            texcoords << (float)(quad.originalRight() - rect.x()) / width;
            texcoords << (float)(quad.originalTop() - rect.y()) / height;
            texcoords << (float)(quad.originalLeft() - rect.x()) / width;
            texcoords << (float)(quad.originalTop() - rect.y()) / height;
            texcoords << (float)(quad.originalLeft() - rect.x()) / width;
            texcoords << (float)(quad.originalBottom() - rect.y()) / height;
            texcoords << (float)(quad.originalLeft() - rect.x()) / width;
            texcoords << (float)(quad.originalBottom() - rect.y()) / height;
            texcoords << (float)(quad.originalRight() - rect.x()) / width;
            texcoords << (float)(quad.originalBottom() - rect.y()) / height;
            texcoords << (float)(quad.originalRight() - rect.x()) / width;
            texcoords << (float)(quad.originalTop() - rect.y()) / height;
        } else {
            texcoords << (float)(quad.originalRight() - rect.x()) / width;
            texcoords << 1.0f - (float)(quad.originalTop() - rect.y()) / height;
            texcoords << (float)(quad.originalLeft() - rect.x()) / width;
            texcoords << 1.0f - (float)(quad.originalTop() - rect.y()) / height;
            texcoords << (float)(quad.originalLeft() - rect.x()) / width;
            texcoords << 1.0f - (float)(quad.originalBottom() - rect.y()) / height;
            texcoords << (float)(quad.originalLeft() - rect.x()) / width;
            texcoords << 1.0f - (float)(quad.originalBottom() - rect.y()) / height;
            texcoords << (float)(quad.originalRight() - rect.x()) / width;
            texcoords << 1.0f - (float)(quad.originalBottom() - rect.y()) / height;
            texcoords << (float)(quad.originalRight() - rect.x()) / width;
            texcoords << 1.0f - (float)(quad.originalTop() - rect.y()) / height;
        }
    }
    GLVertexBuffer::streamingBuffer()->setData(quads.count() * 6, 2, vertices.data(), texcoords.data());
}

void SceneOpenGL::Window::renderQuads(int, const QRegion& region, const WindowQuadList& quads,
                                      GLTexture *tex, bool normalized, bool hardwareClipping)
{
    if (quads.isEmpty())
        return;
    // Render geometry
    float* vertices;
    float* texcoords;
    QSizeF size(tex->size());
    if (normalized) {
        size.setWidth(1.0);
        size.setHeight(1.0);
    }
#ifndef KWIN_HAVE_OPENGLES
    if (tex->target() == GL_TEXTURE_RECTANGLE_ARB) {
        size.setWidth(1.0);
        size.setHeight(1.0);
    }
#endif
    quads.makeArrays(&vertices, &texcoords, size, tex->isYInverted());
    GLVertexBuffer::streamingBuffer()->setData(quads.count() * 6, 2, vertices, texcoords);
    GLVertexBuffer::streamingBuffer()->render(region, GL_TRIANGLES, hardwareClipping);
    delete[] vertices;
    delete[] texcoords;
}

GLTexture *SceneOpenGL::Window::textureForType(SceneOpenGL::Window::TextureType type)
{
    GLTexture *tex = NULL;
    switch(type) {
    case Content:
        tex = texture;
        break;
    case DecorationTop:
        tex = topTexture;
        break;
    case DecorationLeft:
        tex = leftTexture;
        break;
    case DecorationRight:
        tex = rightTexture;
        break;
    case DecorationBottom:
        tex = bottomTexture;
        break;
    case Shadow:
        tex = static_cast<SceneOpenGLShadow*>(m_shadow)->shadowTexture();
    }
    return tex;
}


//***************************************
// SceneOpenGL2Window
//***************************************
SceneOpenGL2Window::SceneOpenGL2Window(Toplevel *c)
    : SceneOpenGL::Window(c)
    , m_blendingEnabled(false)
{
}

SceneOpenGL2Window::~SceneOpenGL2Window()
{
}

void SceneOpenGL2Window::beginRenderWindow(int mask, const WindowPaintData &data)
{
    GLShader *shader = data.shader;
    if (!shader) {
        // set the shader for uniform initialising in paint decoration
        if ((mask & Scene::PAINT_WINDOW_TRANSFORMED) || (mask & Scene::PAINT_SCREEN_TRANSFORMED)) {
            shader = ShaderManager::instance()->pushShader(ShaderManager::GenericShader);
        } else {
            shader = ShaderManager::instance()->pushShader(ShaderManager::SimpleShader);
            shader->setUniform(GLShader::Offset, QVector2D(x(), y()));
        }
    }

    shader->setUniform(GLShader::WindowTransformation, transformation(mask, data));

    static_cast<SceneOpenGL2*>(m_scene)->colorCorrection()->setupForOutput(data.screen());
}

void SceneOpenGL2Window::endRenderWindow(const WindowPaintData &data)
{
    if (!data.shader) {
        ShaderManager::instance()->popShader();
    }
}

void SceneOpenGL2Window::prepareStates(TextureType type, qreal opacity, qreal brightness, qreal saturation, int screen)
{
    // setup blending of transparent windows
    bool opaque = isOpaque() && opacity == 1.0;
    bool alpha = toplevel->hasAlpha() || type != Content;
    if (type != Content) {
        if (type == Shadow) {
            opaque = false;
        } else {
            if (opacity == 1.0 && toplevel->isClient()) {
                opaque = !(static_cast<Client*>(toplevel)->decorationHasAlpha());
            } else {
                // TODO: add support in Deleted
                opaque = false;
            }
        }
    }
    if (!opaque) {
        glEnable(GL_BLEND);
        if (options->isColorCorrected()) {
            glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        } else {
            if (alpha) {
                glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
            } else {
                glBlendColor((float)opacity, (float)opacity, (float)opacity, (float)opacity);
                glBlendFunc(GL_ONE, GL_ONE_MINUS_CONSTANT_ALPHA);
            }
        }
    }
    m_blendingEnabled = !opaque;

    const qreal rgb = brightness * opacity;
    const qreal a = opacity;

    GLShader *shader = ShaderManager::instance()->getBoundShader();
    shader->setUniform(GLShader::ModulationConstant, QVector4D(rgb, rgb, rgb, a));
    shader->setUniform(GLShader::Saturation,         saturation);

    static_cast<SceneOpenGL2*>(m_scene)->colorCorrection()->setupForOutput(screen);
}

void SceneOpenGL2Window::restoreStates(TextureType type, qreal opacity, qreal brightness, qreal saturation)
{
    Q_UNUSED(type);
    Q_UNUSED(opacity);
    Q_UNUSED(brightness);
    Q_UNUSED(saturation);
    if (m_blendingEnabled) {
        glDisable(GL_BLEND);
    }

    static_cast<SceneOpenGL2*>(m_scene)->colorCorrection()->setupForOutput(-1);
}

//***************************************
// SceneOpenGL1Window
//***************************************
#ifdef KWIN_HAVE_OPENGL_1
SceneOpenGL1Window::SceneOpenGL1Window(Toplevel *c)
    : SceneOpenGL::Window(c)
{
}

SceneOpenGL1Window::~SceneOpenGL1Window()
{
}

void SceneOpenGL1Window::beginRenderWindow(int mask, const WindowPaintData &data)
{
    pushMatrix(transformation(mask, data));
}

void SceneOpenGL1Window::endRenderWindow(const WindowPaintData &data)
{
    Q_UNUSED(data)
    popMatrix();
}

void SceneOpenGL1Window::prepareStates(TextureType type, qreal opacity, qreal brightness, qreal saturation, int screen)
{
    Q_UNUSED(screen)

    GLTexture *tex = textureForType(type);
    bool alpha = false;
    bool opaque = true;
    if (type == Content) {
        alpha = toplevel->hasAlpha();
        opaque = isOpaque() && opacity == 1.0;
    } else {
        alpha = true;
        opaque = false;
    }
    // setup blending of transparent windows
    glPushAttrib(GL_ENABLE_BIT);
    if (!opaque) {
        glEnable(GL_BLEND);
        glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
    }
    if (saturation != 1.0 && tex->saturationSupported()) {
        // First we need to get the color from [0; 1] range to [0.5; 1] range
        glActiveTexture(GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_INTERPOLATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_CONSTANT);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_ALPHA);
        const float scale_constant[] = { 1.0, 1.0, 1.0, 0.5};
        glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, scale_constant);
        tex->bind();

        // Then we take dot product of the result of previous pass and
        //  saturation_constant. This gives us completely unsaturated
        //  (greyscale) image
        // Note that both operands have to be in range [0.5; 1] since opengl
        //  automatically substracts 0.5 from them
        glActiveTexture(GL_TEXTURE1);
        float saturation_constant[] = { 0.5 + 0.5 * 0.30, 0.5 + 0.5 * 0.59, 0.5 + 0.5 * 0.11,
                                        static_cast<float>(saturation) };
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_DOT3_RGB);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, saturation_constant);
        tex->bind();

        // Finally we need to interpolate between the original image and the
        //  greyscale image to get wanted level of saturation
        glActiveTexture(GL_TEXTURE2);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_INTERPOLATE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE0);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_CONSTANT);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_ALPHA);
        glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, saturation_constant);
        // Also replace alpha by primary color's alpha here
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PRIMARY_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
        // And make primary color contain the wanted opacity
        glColor4f(opacity, opacity, opacity, opacity);
        tex->bind();

        if (alpha || brightness != 1.0f) {
            glActiveTexture(GL_TEXTURE3);
            glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PRIMARY_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
            // The color has to be multiplied by both opacity and brightness
            float opacityByBrightness = opacity * brightness;
            glColor4f(opacityByBrightness, opacityByBrightness, opacityByBrightness, opacity);
            if (alpha) {
                // Multiply original texture's alpha by our opacity
                glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_MODULATE);
                glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE0);
                glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
                glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA, GL_PRIMARY_COLOR);
                glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA, GL_SRC_ALPHA);
            } else {
                // Alpha will be taken from previous stage
                glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
                glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
                glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
            }
            tex->bind();
        }

        glActiveTexture(GL_TEXTURE0);
    } else if (opacity != 1.0 || brightness != 1.0) {
        // the window is additionally configured to have its opacity adjusted,
        // do it
        float opacityByBrightness = opacity * brightness;
        if (alpha) {
            glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
            glColor4f(opacityByBrightness, opacityByBrightness, opacityByBrightness,
                      opacity);
        } else {
            // Multiply color by brightness and replace alpha by opacity
            float constant[] = { opacityByBrightness, opacityByBrightness, opacityByBrightness,
                                 static_cast<float>(opacity) };
            glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_CONSTANT);
            glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
            glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
            glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_CONSTANT);
            glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, constant);
        }
    } else if (!alpha && opaque) {
        float constant[] = { 1.0, 1.0, 1.0, 1.0 };
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_CONSTANT);
        glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, constant);
    }
}

void SceneOpenGL1Window::restoreStates(TextureType type, qreal opacity, qreal brightness, qreal saturation)
{
    GLTexture *tex = textureForType(type);
    if (opacity != 1.0 || saturation != 1.0 || brightness != 1.0f) {
        if (saturation != 1.0 && tex->saturationSupported()) {
            glActiveTexture(GL_TEXTURE3);
            glDisable(tex->target());
            glActiveTexture(GL_TEXTURE2);
            glDisable(tex->target());
            glActiveTexture(GL_TEXTURE1);
            glDisable(tex->target());
            glActiveTexture(GL_TEXTURE0);
        }
    }
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glColor4f(0, 0, 0, 0);

    glPopAttrib();  // ENABLE_BIT
}
#endif

//****************************************
// SceneOpenGL::EffectFrame
//****************************************

GLTexture* SceneOpenGL::EffectFrame::m_unstyledTexture = NULL;
QPixmap* SceneOpenGL::EffectFrame::m_unstyledPixmap = NULL;

SceneOpenGL::EffectFrame::EffectFrame(EffectFrameImpl* frame, SceneOpenGL *scene)
    : Scene::EffectFrame(frame)
    , m_texture(NULL)
    , m_textTexture(NULL)
    , m_oldTextTexture(NULL)
    , m_textPixmap(NULL)
    , m_iconTexture(NULL)
    , m_oldIconTexture(NULL)
    , m_selectionTexture(NULL)
    , m_unstyledVBO(NULL)
    , m_scene(scene)
{
    if (m_effectFrame->style() == EffectFrameUnstyled && !m_unstyledTexture) {
        updateUnstyledTexture();
    }
}

SceneOpenGL::EffectFrame::~EffectFrame()
{
    delete m_texture;
    delete m_textTexture;
    delete m_textPixmap;
    delete m_oldTextTexture;
    delete m_iconTexture;
    delete m_oldIconTexture;
    delete m_selectionTexture;
    delete m_unstyledVBO;
}

void SceneOpenGL::EffectFrame::free()
{
    glFlush();
    delete m_texture;
    m_texture = NULL;
    delete m_textTexture;
    m_textTexture = NULL;
    delete m_textPixmap;
    m_textPixmap = NULL;
    delete m_iconTexture;
    m_iconTexture = NULL;
    delete m_selectionTexture;
    m_selectionTexture = NULL;
    delete m_unstyledVBO;
    m_unstyledVBO = NULL;
    delete m_oldIconTexture;
    m_oldIconTexture = NULL;
    delete m_oldTextTexture;
    m_oldTextTexture = NULL;
}

void SceneOpenGL::EffectFrame::freeIconFrame()
{
    delete m_iconTexture;
    m_iconTexture = NULL;
}

void SceneOpenGL::EffectFrame::freeTextFrame()
{
    delete m_textTexture;
    m_textTexture = NULL;
    delete m_textPixmap;
    m_textPixmap = NULL;
}

void SceneOpenGL::EffectFrame::freeSelection()
{
    delete m_selectionTexture;
    m_selectionTexture = NULL;
}

void SceneOpenGL::EffectFrame::crossFadeIcon()
{
    delete m_oldIconTexture;
    m_oldIconTexture = m_iconTexture;
    m_iconTexture = NULL;
}

void SceneOpenGL::EffectFrame::crossFadeText()
{
    delete m_oldTextTexture;
    m_oldTextTexture = m_textTexture;
    m_textTexture = NULL;
}

void SceneOpenGL::EffectFrame::render(QRegion region, double opacity, double frameOpacity)
{
    if (m_effectFrame->geometry().isEmpty())
        return; // Nothing to display

    region = infiniteRegion(); // TODO: Old region doesn't seem to work with OpenGL

    GLShader* shader = m_effectFrame->shader();
    bool sceneShader = false;
    if (!shader && ShaderManager::instance()->isValid()) {
        shader = ShaderManager::instance()->pushShader(ShaderManager::SimpleShader);
        sceneShader = true;
    } else if (shader) {
        ShaderManager::instance()->pushShader(shader);
    }

    if (shader) {
        if (sceneShader)
            shader->setUniform(GLShader::Offset, QVector2D(0, 0));

        shader->setUniform(GLShader::ModulationConstant, QVector4D(1.0, 1.0, 1.0, 1.0));
        shader->setUniform(GLShader::Saturation, 1.0f);
    }

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
#ifdef KWIN_HAVE_OPENGL_1
    if (!shader)
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
#endif

    // Render the actual frame
    if (m_effectFrame->style() == EffectFrameUnstyled) {
        if (!m_unstyledVBO) {
            m_unstyledVBO = new GLVertexBuffer(GLVertexBuffer::Static);
            QRect area = m_effectFrame->geometry();
            area.moveTo(0, 0);
            area.adjust(-5, -5, 5, 5);

            const int roundness = 5;
            QVector<float> verts, texCoords;
            verts.reserve(84);
            texCoords.reserve(84);

            // top left
            verts << area.left() << area.top();
            texCoords << 0.0f << 0.0f;
            verts << area.left() << area.top() + roundness;
            texCoords << 0.0f << 0.5f;
            verts << area.left() + roundness << area.top();
            texCoords << 0.5f << 0.0f;
            verts << area.left() + roundness << area.top() + roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.left() << area.top() + roundness;
            texCoords << 0.0f << 0.5f;
            verts << area.left() + roundness << area.top();
            texCoords << 0.5f << 0.0f;
            // top
            verts << area.left() + roundness << area.top();
            texCoords << 0.5f << 0.0f;
            verts << area.left() + roundness << area.top() + roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.right() - roundness << area.top();
            texCoords << 0.5f << 0.0f;
            verts << area.left() + roundness << area.top() + roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.right() - roundness << area.top() + roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.right() - roundness << area.top();
            texCoords << 0.5f << 0.0f;
            // top right
            verts << area.right() - roundness << area.top();
            texCoords << 0.5f << 0.0f;
            verts << area.right() - roundness << area.top() + roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.right() << area.top();
            texCoords << 1.0f << 0.0f;
            verts << area.right() - roundness << area.top() + roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.right() << area.top() + roundness;
            texCoords << 1.0f << 0.5f;
            verts << area.right() << area.top();
            texCoords << 1.0f << 0.0f;
            // bottom left
            verts << area.left() << area.bottom() - roundness;
            texCoords << 0.0f << 0.5f;
            verts << area.left() << area.bottom();
            texCoords << 0.0f << 1.0f;
            verts << area.left() + roundness << area.bottom() - roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.left() + roundness << area.bottom();
            texCoords << 0.5f << 1.0f;
            verts << area.left() << area.bottom();
            texCoords << 0.0f << 1.0f;
            verts << area.left() + roundness << area.bottom() - roundness;
            texCoords << 0.5f << 0.5f;
            // bottom
            verts << area.left() + roundness << area.bottom() - roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.left() + roundness << area.bottom();
            texCoords << 0.5f << 1.0f;
            verts << area.right() - roundness << area.bottom() - roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.left() + roundness << area.bottom();
            texCoords << 0.5f << 1.0f;
            verts << area.right() - roundness << area.bottom();
            texCoords << 0.5f << 1.0f;
            verts << area.right() - roundness << area.bottom() - roundness;
            texCoords << 0.5f << 0.5f;
            // bottom right
            verts << area.right() - roundness << area.bottom() - roundness;
            texCoords << 0.5f << 0.5f;
            verts << area.right() - roundness << area.bottom();
            texCoords << 0.5f << 1.0f;
            verts << area.right() << area.bottom() - roundness;
            texCoords << 1.0f << 0.5f;
            verts << area.right() - roundness << area.bottom();
            texCoords << 0.5f << 1.0f;
            verts << area.right() << area.bottom();
            texCoords << 1.0f << 1.0f;
            verts << area.right() << area.bottom() - roundness;
            texCoords << 1.0f << 0.5f;
            // center
            verts << area.left() << area.top() + roundness;
            texCoords << 0.0f << 0.5f;
            verts << area.left() << area.bottom() - roundness;
            texCoords << 0.0f << 0.5f;
            verts << area.right() << area.top() + roundness;
            texCoords << 1.0f << 0.5f;
            verts << area.left() << area.bottom() - roundness;
            texCoords << 0.0f << 0.5f;
            verts << area.right() << area.bottom() - roundness;
            texCoords << 1.0f << 0.5f;
            verts << area.right() << area.top() + roundness;
            texCoords << 1.0f << 0.5f;

            m_unstyledVBO->setData(verts.count() / 2, 2, verts.data(), texCoords.data());
        }

        if (shader) {
            const float a = opacity * frameOpacity;
            shader->setUniform(GLShader::ModulationConstant, QVector4D(a, a, a, a));
        }
#ifdef KWIN_HAVE_OPENGL_1
        else
            glColor4f(0.0, 0.0, 0.0, opacity * frameOpacity);
#endif

        m_unstyledTexture->bind();
        const QPoint pt = m_effectFrame->geometry().topLeft();
        if (sceneShader) {
            shader->setUniform(GLShader::Offset, QVector2D(pt.x(), pt.y()));
        } else {
            QMatrix4x4 translation;
            translation.translate(pt.x(), pt.y());
            if (shader) {
                shader->setUniform(GLShader::WindowTransformation, translation);
            } else {
                pushMatrix(translation);
            }
        }
        m_unstyledVBO->render(region, GL_TRIANGLES);
        if (!sceneShader) {
            if (shader) {
                shader->setUniform(GLShader::WindowTransformation, QMatrix4x4());
            } else {
                popMatrix();
            }
        }
        m_unstyledTexture->unbind();
    } else if (m_effectFrame->style() == EffectFrameStyled) {
        if (!m_texture)   // Lazy creation
            updateTexture();

        if (shader) {
            const float a = opacity * frameOpacity;
            shader->setUniform(GLShader::ModulationConstant, QVector4D(a, a, a, a));
        }
#ifdef KWIN_HAVE_OPENGL_1
        else
            glColor4f(1.0, 1.0, 1.0, opacity * frameOpacity);
#endif
        m_texture->bind();
        qreal left, top, right, bottom;
        m_effectFrame->frame().getMargins(left, top, right, bottom);   // m_geometry is the inner geometry
        m_texture->render(region, m_effectFrame->geometry().adjusted(-left, -top, right, bottom));
        m_texture->unbind();

    }
    if (!m_effectFrame->selection().isNull()) {
        if (!m_selectionTexture) { // Lazy creation
            QPixmap pixmap = m_effectFrame->selectionFrame().framePixmap();
            if (!pixmap.isNull())
                m_selectionTexture = m_scene->createTexture(pixmap);
        }
        if (m_selectionTexture) {
            if (shader) {
                const float a = opacity * frameOpacity;
                shader->setUniform(GLShader::ModulationConstant, QVector4D(a, a, a, a));
            }
    #ifdef KWIN_HAVE_OPENGL_1
            else
                glColor4f(1.0, 1.0, 1.0, opacity * frameOpacity);
    #endif
            glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
            m_selectionTexture->bind();
            m_selectionTexture->render(region, m_effectFrame->selection());
            m_selectionTexture->unbind();
            glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        }
    }

    // Render icon
    if (!m_effectFrame->icon().isNull() && !m_effectFrame->iconSize().isEmpty()) {
        QPoint topLeft(m_effectFrame->geometry().x(),
                       m_effectFrame->geometry().center().y() - m_effectFrame->iconSize().height() / 2);

        if (m_effectFrame->isCrossFade() && m_oldIconTexture) {
            if (shader) {
                const float a = opacity * (1.0 - m_effectFrame->crossFadeProgress());
                shader->setUniform(GLShader::ModulationConstant, QVector4D(a, a, a, a));
            }
#ifdef KWIN_HAVE_OPENGL_1
            else
                glColor4f(1.0, 1.0, 1.0, opacity * (1.0 - m_effectFrame->crossFadeProgress()));
#endif

            m_oldIconTexture->bind();
            m_oldIconTexture->render(region, QRect(topLeft, m_effectFrame->iconSize()));
            m_oldIconTexture->unbind();
            if (shader) {
                const float a = opacity * m_effectFrame->crossFadeProgress();
                shader->setUniform(GLShader::ModulationConstant, QVector4D(a, a, a, a));
            }
#ifdef KWIN_HAVE_OPENGL_1
            else
                glColor4f(1.0, 1.0, 1.0, opacity * m_effectFrame->crossFadeProgress());
#endif
        } else {
            if (shader) {
                const QVector4D constant(opacity, opacity, opacity, opacity);
                shader->setUniform(GLShader::ModulationConstant, constant);
            }
#ifdef KWIN_HAVE_OPENGL_1
            else
                glColor4f(1.0, 1.0, 1.0, opacity);
#endif
        }

        if (!m_iconTexture) { // lazy creation
            m_iconTexture = m_scene->createTexture(m_effectFrame->icon());
        }
        m_iconTexture->bind();
        m_iconTexture->render(region, QRect(topLeft, m_effectFrame->iconSize()));
        m_iconTexture->unbind();
    }

    // Render text
    if (!m_effectFrame->text().isEmpty()) {
        if (m_effectFrame->isCrossFade() && m_oldTextTexture) {
            if (shader) {
                const float a = opacity * (1.0 - m_effectFrame->crossFadeProgress());
                shader->setUniform(GLShader::ModulationConstant, QVector4D(a, a, a, a));
            }
#ifdef KWIN_HAVE_OPENGL_1
            else
                glColor4f(1.0, 1.0, 1.0, opacity *(1.0 - m_effectFrame->crossFadeProgress()));
#endif

            m_oldTextTexture->bind();
            m_oldTextTexture->render(region, m_effectFrame->geometry());
            m_oldTextTexture->unbind();
            if (shader) {
                const float a = opacity * m_effectFrame->crossFadeProgress();
                shader->setUniform(GLShader::ModulationConstant, QVector4D(a, a, a, a));
            }
#ifdef KWIN_HAVE_OPENGL_1
            else
                glColor4f(1.0, 1.0, 1.0, opacity * m_effectFrame->crossFadeProgress());
#endif
        } else {
            if (shader) {
                const QVector4D constant(opacity, opacity, opacity, opacity);
                shader->setUniform(GLShader::ModulationConstant, constant);
            }
#ifdef KWIN_HAVE_OPENGL_1
            else
                glColor4f(1.0, 1.0, 1.0, opacity);
#endif
        }
        if (!m_textTexture)   // Lazy creation
            updateTextTexture();
        m_textTexture->bind();
        m_textTexture->render(region, m_effectFrame->geometry());
        m_textTexture->unbind();
    }

    if (shader) {
        ShaderManager::instance()->popShader();
    }
    glDisable(GL_BLEND);
}

void SceneOpenGL::EffectFrame::updateTexture()
{
    delete m_texture;
    m_texture = 0L;
    if (m_effectFrame->style() == EffectFrameStyled) {
        QPixmap pixmap = m_effectFrame->frame().framePixmap();
        m_texture = m_scene->createTexture(pixmap);
    }
}

void SceneOpenGL::EffectFrame::updateTextTexture()
{
    delete m_textTexture;
    m_textTexture = 0L;
    delete m_textPixmap;
    m_textPixmap = 0L;

    if (m_effectFrame->text().isEmpty())
        return;

    // Determine position on texture to paint text
    QRect rect(QPoint(0, 0), m_effectFrame->geometry().size());
    if (!m_effectFrame->icon().isNull() && !m_effectFrame->iconSize().isEmpty())
        rect.setLeft(m_effectFrame->iconSize().width());

    // If static size elide text as required
    QString text = m_effectFrame->text();
    if (m_effectFrame->isStatic()) {
        QFontMetrics metrics(m_effectFrame->font());
        text = metrics.elidedText(text, Qt::ElideRight, rect.width());
    }

    m_textPixmap = new QPixmap(m_effectFrame->geometry().size());
    m_textPixmap->fill(Qt::transparent);
    QPainter p(m_textPixmap);
    p.setFont(m_effectFrame->font());
    if (m_effectFrame->style() == EffectFrameStyled)
        p.setPen(m_effectFrame->styledTextColor());
    else // TODO: What about no frame? Custom color setting required
        p.setPen(Qt::white);
    p.drawText(rect, m_effectFrame->alignment(), text);
    p.end();
    m_textTexture = m_scene->createTexture(*m_textPixmap);
}

void SceneOpenGL::EffectFrame::updateUnstyledTexture()
{
    delete m_unstyledTexture;
    m_unstyledTexture = 0L;
    delete m_unstyledPixmap;
    m_unstyledPixmap = 0L;
    // Based off circle() from kwinxrenderutils.cpp
#define CS 8
    m_unstyledPixmap = new QPixmap(2 * CS, 2 * CS);
    m_unstyledPixmap->fill(Qt::transparent);
    QPainter p(m_unstyledPixmap);
    p.setRenderHint(QPainter::Antialiasing);
    p.setPen(Qt::NoPen);
    p.setBrush(Qt::black);
    p.drawEllipse(m_unstyledPixmap->rect());
    p.end();
#undef CS
    m_unstyledTexture = new GLTexture(*m_unstyledPixmap);
}

void SceneOpenGL::EffectFrame::cleanup()
{
    delete m_unstyledTexture;
    m_unstyledTexture = NULL;
    delete m_unstyledPixmap;
    m_unstyledPixmap = NULL;
}

//****************************************
// SceneOpenGL::Shadow
//****************************************
SceneOpenGLShadow::SceneOpenGLShadow(Toplevel *toplevel)
    : Shadow(toplevel)
    , m_texture(NULL)
{
}

SceneOpenGLShadow::~SceneOpenGLShadow()
{
    delete m_texture;
}

void SceneOpenGLShadow::buildQuads()
{
    // prepare window quads
    m_shadowQuads.clear();
    const QSizeF top(shadowPixmap(ShadowElementTop).size());
    const QSizeF topRight(shadowPixmap(ShadowElementTopRight).size());
    const QSizeF right(shadowPixmap(ShadowElementRight).size());
    const QSizeF bottomRight(shadowPixmap(ShadowElementBottomRight).size());
    const QSizeF bottom(shadowPixmap(ShadowElementBottom).size());
    const QSizeF bottomLeft(shadowPixmap(ShadowElementBottomLeft).size());
    const QSizeF left(shadowPixmap(ShadowElementLeft).size());
    const QSizeF topLeft(shadowPixmap(ShadowElementTopLeft).size());
    if ((left.width() - leftOffset() > topLevel()->width()) ||
        (right.width() - rightOffset() > topLevel()->width()) ||
        (top.height() - topOffset() > topLevel()->height()) ||
        (bottom.height() - bottomOffset() > topLevel()->height())) {
        // if our shadow is bigger than the window, we don't render the shadow
        setShadowRegion(QRegion());
        return;
    }

    const QRectF outerRect(QPointF(-leftOffset(), -topOffset()),
                           QPointF(topLevel()->width() + rightOffset(), topLevel()->height() + bottomOffset()));

    const qreal width = topLeft.width() + top.width() + topRight.width();
    const qreal height = topLeft.height() + left.height() + bottomLeft.height();

    qreal tx1(0.0), tx2(0.0), ty1(0.0), ty2(0.0);

    tx2 = topLeft.width()/width;
    ty2 = topLeft.height()/height;
    WindowQuad topLeftQuad(WindowQuadShadowTopLeft);
    topLeftQuad[ 0 ] = WindowVertex(outerRect.x(),                      outerRect.y(), tx1, ty1);
    topLeftQuad[ 1 ] = WindowVertex(outerRect.x() + topLeft.width(),    outerRect.y(), tx2, ty1);
    topLeftQuad[ 2 ] = WindowVertex(outerRect.x() + topLeft.width(),    outerRect.y() + topLeft.height(), tx2, ty2);
    topLeftQuad[ 3 ] = WindowVertex(outerRect.x(),                      outerRect.y() + topLeft.height(), tx1, ty2);
    m_shadowQuads.append(topLeftQuad);

    tx1 = tx2;
    tx2 = (topLeft.width() + top.width())/width;
    ty2 = top.height()/height;
    WindowQuad topQuad(WindowQuadShadowTop);
    topQuad[ 0 ] = WindowVertex(outerRect.x() + topLeft.width(),        outerRect.y(), tx1, ty1);
    topQuad[ 1 ] = WindowVertex(outerRect.right() - topRight.width(),   outerRect.y(), tx2, ty1);
    topQuad[ 2 ] = WindowVertex(outerRect.right() - topRight.width(),   outerRect.y() + top.height(),tx2, ty2);
    topQuad[ 3 ] = WindowVertex(outerRect.x() + topLeft.width(),        outerRect.y() + top.height(), tx1, ty2);
    m_shadowQuads.append(topQuad);

    tx1 = tx2;
    tx2 = 1.0;
    ty2 = topRight.height()/height;
    WindowQuad topRightQuad(WindowQuadShadowTopRight);
    topRightQuad[ 0 ] = WindowVertex(outerRect.right() - topRight.width(),  outerRect.y(), tx1, ty1);
    topRightQuad[ 1 ] = WindowVertex(outerRect.right(),                     outerRect.y(), tx2, ty1);
    topRightQuad[ 2 ] = WindowVertex(outerRect.right(),                     outerRect.y() + topRight.height(), tx2, ty2);
    topRightQuad[ 3 ] = WindowVertex(outerRect.right() - topRight.width(),  outerRect.y() + topRight.height(), tx1, ty2);
    m_shadowQuads.append(topRightQuad);

    tx1 = (width - right.width())/width;
    ty1 = topRight.height()/height;
    ty2 = (topRight.height() + right.height())/height;
    WindowQuad rightQuad(WindowQuadShadowRight);
    rightQuad[ 0 ] = WindowVertex(outerRect.right() - right.width(),    outerRect.y() + topRight.height(), tx1, ty1);
    rightQuad[ 1 ] = WindowVertex(outerRect.right(),                    outerRect.y() + topRight.height(), tx2, ty1);
    rightQuad[ 2 ] = WindowVertex(outerRect.right(),                    outerRect.bottom() - bottomRight.height(), tx2, ty2);
    rightQuad[ 3 ] = WindowVertex(outerRect.right() - right.width(),    outerRect.bottom() - bottomRight.height(), tx1, ty2);
    m_shadowQuads.append(rightQuad);

    tx1 = (width - bottomRight.width())/width;
    ty1 = ty2;
    ty2 = 1.0;
    WindowQuad bottomRightQuad(WindowQuadShadowBottomRight);
    bottomRightQuad[ 0 ] = WindowVertex(outerRect.right() - bottomRight.width(),    outerRect.bottom() - bottomRight.height(), tx1, ty1);
    bottomRightQuad[ 1 ] = WindowVertex(outerRect.right(),                          outerRect.bottom() - bottomRight.height(), tx2, ty1);
    bottomRightQuad[ 2 ] = WindowVertex(outerRect.right(),                          outerRect.bottom(), tx2, ty2);
    bottomRightQuad[ 3 ] = WindowVertex(outerRect.right() - bottomRight.width(),    outerRect.bottom(), tx1, ty2);
    m_shadowQuads.append(bottomRightQuad);

    tx2 = tx1;
    tx1 = bottomLeft.width()/width;
    ty1 = (height - bottom.height())/height;
    WindowQuad bottomQuad(WindowQuadShadowBottom);
    bottomQuad[ 0 ] = WindowVertex(outerRect.x() + bottomLeft.width(),      outerRect.bottom() - bottom.height(), tx1, ty1);
    bottomQuad[ 1 ] = WindowVertex(outerRect.right() - bottomRight.width(), outerRect.bottom() - bottom.height(), tx2, ty1);
    bottomQuad[ 2 ] = WindowVertex(outerRect.right() - bottomRight.width(), outerRect.bottom(), tx2, ty2);
    bottomQuad[ 3 ] = WindowVertex(outerRect.x() + bottomLeft.width(),      outerRect.bottom(), tx1, ty2);
    m_shadowQuads.append(bottomQuad);

    tx1 = 0.0;
    tx2 = bottomLeft.width()/width;
    ty1 = (height - bottomLeft.height())/height;
    WindowQuad bottomLeftQuad(WindowQuadShadowBottomLeft);
    bottomLeftQuad[ 0 ] = WindowVertex(outerRect.x(),                       outerRect.bottom() - bottomLeft.height(), tx1, ty1);
    bottomLeftQuad[ 1 ] = WindowVertex(outerRect.x() + bottomLeft.width(),  outerRect.bottom() - bottomLeft.height(), tx2, ty1);
    bottomLeftQuad[ 2 ] = WindowVertex(outerRect.x() + bottomLeft.width(),  outerRect.bottom(), tx2, ty2);
    bottomLeftQuad[ 3 ] = WindowVertex(outerRect.x(),                       outerRect.bottom(), tx1, ty2);
    m_shadowQuads.append(bottomLeftQuad);

    tx2 = left.width()/width;
    ty2 = ty1;
    ty1 = topLeft.height()/height;
    WindowQuad leftQuad(WindowQuadShadowLeft);
    leftQuad[ 0 ] = WindowVertex(outerRect.x(),                 outerRect.y() + topLeft.height(), tx1, ty1);
    leftQuad[ 1 ] = WindowVertex(outerRect.x() + left.width(),  outerRect.y() + topLeft.height(), tx2, ty1);
    leftQuad[ 2 ] = WindowVertex(outerRect.x() + left.width(),  outerRect.bottom() - bottomLeft.height(), tx2, ty2);
    leftQuad[ 3 ] = WindowVertex(outerRect.x(),                 outerRect.bottom() - bottomLeft.height(), tx1, ty2);
    m_shadowQuads.append(leftQuad);
}

bool SceneOpenGLShadow::prepareBackend()
{
    const QSize top(shadowPixmap(ShadowElementTop).size());
    const QSize topRight(shadowPixmap(ShadowElementTopRight).size());
    const QSize right(shadowPixmap(ShadowElementRight).size());
    const QSize bottomRight(shadowPixmap(ShadowElementBottomRight).size());
    const QSize bottom(shadowPixmap(ShadowElementBottom).size());
    const QSize bottomLeft(shadowPixmap(ShadowElementBottomLeft).size());
    const QSize left(shadowPixmap(ShadowElementLeft).size());
    const QSize topLeft(shadowPixmap(ShadowElementTopLeft).size());

    const int width = topLeft.width() + top.width() + topRight.width();
    const int height = topLeft.height() + left.height() + bottomLeft.height();

    QImage image(width, height, QImage::Format_ARGB32);
    image.fill(Qt::transparent);
    QPainter p;
    p.begin(&image);
    p.drawPixmap(0, 0, shadowPixmap(ShadowElementTopLeft));
    p.drawPixmap(topLeft.width(), 0, shadowPixmap(ShadowElementTop));
    p.drawPixmap(topLeft.width() + top.width(), 0, shadowPixmap(ShadowElementTopRight));
    p.drawPixmap(0, topLeft.height(), shadowPixmap(ShadowElementLeft));
    p.drawPixmap(width - right.width(), topRight.height(), shadowPixmap(ShadowElementRight));
    p.drawPixmap(0, topLeft.height() + left.height(), shadowPixmap(ShadowElementBottomLeft));
    p.drawPixmap(bottomLeft.width(), height - bottom.height(), shadowPixmap(ShadowElementBottom));
    p.drawPixmap(bottomLeft.width() + bottom.width(), topRight.height() + right.height(), shadowPixmap(ShadowElementBottomRight));
    p.end();

    delete m_texture;
    m_texture = new GLTexture(image);

    return true;
}

} // namespace