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

**

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

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the examples of the Qt Toolkit.

**

** $QT_BEGIN_LICENSE:LGPL$

** No Commercial Usage

** This file contains pre-release code and may not be distributed.

** You may use this file in accordance with the terms and conditions

** contained in the Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

** Alternatively, 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.

**

** If you have questions regarding the use of this file, please contact

** Nokia at qt-info@nokia.com.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

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

#include "glwidget.h"

#include <math.h>

#include "cube.h"

#include <QGLPixelBuffer>

#ifndef GL_MULTISAMPLE

#define GL_MULTISAMPLE  0x809D

#endif

static GLfloat colorArray[][4] = {

    {0.243f, 0.423f, 0.125f, 1.0f},

    {0.176f, 0.31f, 0.09f, 1.0f},

    {0.4f, 0.69f, 0.212f, 1.0f},

    {0.317f, 0.553f, 0.161f, 1.0f}

};

GLWidget::GLWidget(QWidget *parent)

    : QGLWidget(QGLFormat(QGL::SampleBuffers), parent)

    , geom(0)

    , cube(0)

{

    // create the pbuffer

    pbuffer = new QGLPixelBuffer(QSize(512, 512), format(), this);

    setWindowTitle(tr("OpenGL pbuffers"));

    initializeGeometry();

}

GLWidget::~GLWidget()

{

    pbuffer->releaseFromDynamicTexture();

    glDeleteTextures(1, &dynamicTexture);

    delete pbuffer;

    qDeleteAll(cubes);

    qDeleteAll(tiles);

    delete cube;

}

void GLWidget::initializeGL()

{

    initCommon();

    glShadeModel(GL_SMOOTH);

    glEnable(GL_LIGHTING);

    glEnable(GL_LIGHT0);

    static GLfloat lightPosition[4] = { 0.5, 5.0, 7.0, 1.0 };

    glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);

    initPbuffer();

    cube->startAnimation();

    connect(cube, SIGNAL(changed()), this, SLOT(update()));

    for (int i = 0; i < 3; ++i)

    {

        cubes[i]->startAnimation();

        connect(cubes[i], SIGNAL(changed()), this, SLOT(update()));

    }

}

void GLWidget::paintGL()

{

    pbuffer->makeCurrent();

    drawPbuffer();

    // On direct render platforms, drawing onto the pbuffer context above

    // automatically updates the dynamic texture.  For cases where rendering

    // directly to a texture is not supported, explicitly copy.

    if (!hasDynamicTextureUpdate)

        pbuffer->updateDynamicTexture(dynamicTexture);

    makeCurrent();

    // Use the pbuffer as a texture to render the scene

    glBindTexture(GL_TEXTURE_2D, dynamicTexture);

    // set up to render the scene

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glLoadIdentity();

    glTranslatef(0.0f, 0.0f, -10.0f);

    // draw the background

    glPushMatrix();

    glScalef(aspect, 1.0f, 1.0f);

    for (int i = 0; i < tiles.count(); ++i)

        tiles[i]->draw();

    glPopMatrix();

    // draw the bouncing cubes

    for (int i = 0; i < cubes.count(); ++i)

        cubes[i]->draw();

}

void GLWidget::initializeGeometry()

{

    geom = new Geometry();

    CubeBuilder cBuilder(geom, 0.5);

    cBuilder.setColor(QColor(255, 255, 255, 212));

    // build the 3 bouncing, spinning cubes

    for (int i = 0; i < 3; ++i)

        cubes.append(cBuilder.newCube(QVector3D((float)(i-1), -1.5f, 5 - i)));

    // build the spinning cube which goes in the dynamic texture

    cube = cBuilder.newCube();

    cube->removeBounce();

    // build the background tiles

    TileBuilder tBuilder(geom);

    tBuilder.setColor(QColor(Qt::white));

    for (int c = -2; c <= +2; ++c)

        for (int r = -2; r <= +2; ++r)

            tiles.append(tBuilder.newTile(QVector3D(c, r, 0)));

    // graded backdrop for the pbuffer scene

    TileBuilder bBuilder(geom, 0.0f, 2.0f);

    bBuilder.setColor(QColor(102, 176, 54, 210));

    backdrop = bBuilder.newTile(QVector3D(0.0f, 0.0f, -1.5f));

    backdrop->setColors(colorArray);

}

void GLWidget::initCommon()

{

    qglClearColor(QColor(Qt::darkGray));

    glEnable(GL_DEPTH_TEST);

    glEnable(GL_CULL_FACE);

    glEnable(GL_MULTISAMPLE);

    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    glEnable(GL_BLEND);

    glEnable(GL_TEXTURE_2D);

    geom->loadArrays();

}

void GLWidget::perspectiveProjection()

{

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    glFrustum(-aspect, +aspect, -1.0, +1.0, 4.0, 15.0);

    glMatrixMode(GL_MODELVIEW);

}

void GLWidget::orthographicProjection()

{

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    glOrtho(-1.0, +1.0, -1.0, +1.0, -90.0, +90.0);

    glMatrixMode(GL_MODELVIEW);

}

void GLWidget::resizeGL(int width, int height)

{

    glViewport(0, 0, width, height);

    aspect = (qreal)width / (qreal)(height ? height : 1);

    perspectiveProjection();

}

void GLWidget::drawPbuffer()

{

    orthographicProjection();

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glDisable(GL_TEXTURE_2D);

    backdrop->draw();

    glEnable(GL_TEXTURE_2D);

    glBindTexture(GL_TEXTURE_2D, cubeTexture);

    glDisable(GL_CULL_FACE);

    cube->draw();

    glEnable(GL_CULL_FACE);

    glFlush();

}

void GLWidget::initPbuffer()

{

    pbuffer->makeCurrent();

    cubeTexture = bindTexture(QImage(":res/cubelogo.png"));

    initCommon();

    // generate a texture that has the same size/format as the pbuffer

    dynamicTexture = pbuffer->generateDynamicTexture();

    // bind the dynamic texture to the pbuffer - this is a no-op under X11

    hasDynamicTextureUpdate = pbuffer->bindToDynamicTexture(dynamicTexture);

    makeCurrent();

}

void GLWidget::setAnimationPaused(bool enable)

{

    cube->setAnimationPaused(enable);

    for (int i = 0; i < 3; ++i)

        cubes[i]->setAnimationPaused(enable);

}