/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
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**
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**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
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**     from this software without specific prior written permission.
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****************************************************************************/

#include "glwidget.h"
#include <QMouseEvent>
#include <QWheelEvent>

//! [0]
#ifdef WIN32
    #include <GL/glext.h>
    PFNGLACTIVETEXTUREPROC pGlActiveTexture = NULL;
    #define glActiveTexture pGlActiveTexture
#endif //WIN32
//! [0]

GlWidget::GlWidget(QWidget *parent)
    : QGLWidget(QGLFormat(/* Additional format options */), parent)
{
    alpha = 25;
    beta = -25;
    distance = 2.5;
}

GlWidget::~GlWidget()
{
}

QSize GlWidget::sizeHint() const
{
    return QSize(640, 480);
}

//! [1]
void GlWidget::initializeGL()
{
    //! [1]
    //! [2]
    #ifdef WIN32
        glActiveTexture = (PFNGLACTIVETEXTUREPROC) wglGetProcAddress((LPCSTR) "glActiveTexture");
    #endif
    //! [2]

    glEnable(GL_DEPTH_TEST);
    glEnable(GL_CULL_FACE);

    qglClearColor(QColor(Qt::black));

    shaderProgram.addShaderFromSourceFile(QGLShader::Vertex, ":/vertexShader.vsh");
    shaderProgram.addShaderFromSourceFile(QGLShader::Fragment, ":/fragmentShader.fsh");
    shaderProgram.link();

    vertices << QVector3D(-0.5, -0.5,  0.5) << QVector3D( 0.5, -0.5,  0.5) << QVector3D( 0.5,  0.5,  0.5) // Front
             << QVector3D( 0.5,  0.5,  0.5) << QVector3D(-0.5,  0.5,  0.5) << QVector3D(-0.5, -0.5,  0.5)
             << QVector3D( 0.5, -0.5, -0.5) << QVector3D(-0.5, -0.5, -0.5) << QVector3D(-0.5,  0.5, -0.5) // Back
             << QVector3D(-0.5,  0.5, -0.5) << QVector3D( 0.5,  0.5, -0.5) << QVector3D( 0.5, -0.5, -0.5)
             << QVector3D(-0.5, -0.5, -0.5) << QVector3D(-0.5, -0.5,  0.5) << QVector3D(-0.5,  0.5,  0.5) // Left
             << QVector3D(-0.5,  0.5,  0.5) << QVector3D(-0.5,  0.5, -0.5) << QVector3D(-0.5, -0.5, -0.5)
             << QVector3D( 0.5, -0.5,  0.5) << QVector3D( 0.5, -0.5, -0.5) << QVector3D( 0.5,  0.5, -0.5) // Right
             << QVector3D( 0.5,  0.5, -0.5) << QVector3D( 0.5,  0.5,  0.5) << QVector3D( 0.5, -0.5,  0.5)
             << QVector3D(-0.5,  0.5,  0.5) << QVector3D( 0.5,  0.5,  0.5) << QVector3D( 0.5,  0.5, -0.5) // Top
             << QVector3D( 0.5,  0.5, -0.5) << QVector3D(-0.5,  0.5, -0.5) << QVector3D(-0.5,  0.5,  0.5)
             << QVector3D(-0.5, -0.5, -0.5) << QVector3D( 0.5, -0.5, -0.5) << QVector3D( 0.5, -0.5,  0.5) // Bottom
             << QVector3D( 0.5, -0.5,  0.5) << QVector3D(-0.5, -0.5,  0.5) << QVector3D(-0.5, -0.5, -0.5);
    //! [3]
    textureCoordinates << QVector2D(0, 0) << QVector2D(1, 0) << QVector2D(1, 1) // Front
                       << QVector2D(1, 1) << QVector2D(0, 1) << QVector2D(0, 0)
                       << QVector2D(0, 0) << QVector2D(1, 0) << QVector2D(1, 1) // Back
                       << QVector2D(1, 1) << QVector2D(0, 1) << QVector2D(0, 0)
                       << QVector2D(0, 0) << QVector2D(1, 0) << QVector2D(1, 1) // Left
                       << QVector2D(1, 1) << QVector2D(0, 1) << QVector2D(0, 0)
                       << QVector2D(0, 0) << QVector2D(1, 0) << QVector2D(1, 1) // Right
                       << QVector2D(1, 1) << QVector2D(0, 1) << QVector2D(0, 0)
                       << QVector2D(0, 0) << QVector2D(1, 0) << QVector2D(1, 1) // Top
                       << QVector2D(1, 1) << QVector2D(0, 1) << QVector2D(0, 0)
                       << QVector2D(0, 0) << QVector2D(1, 0) << QVector2D(1, 1) // Bottom
                       << QVector2D(1, 1) << QVector2D(0, 1) << QVector2D(0, 0);

    texture = bindTexture(QPixmap(":/texture.png"));
    //! [3]
    //! [4]
}
//! [4]

void GlWidget::resizeGL(int width, int height)
{
    if (height == 0) {
        height = 1;
    }

    pMatrix.setToIdentity();
    pMatrix.perspective(60.0, (float) width / (float) height, 0.001, 1000);

    glViewport(0, 0, width, height);
}

//! [5]
void GlWidget::paintGL()
{
    //! [5]
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    QMatrix4x4 mMatrix;
    QMatrix4x4 vMatrix;

    QMatrix4x4 cameraTransformation;
    cameraTransformation.rotate(alpha, 0, 1, 0);
    cameraTransformation.rotate(beta, 1, 0, 0);

    QVector3D cameraPosition = cameraTransformation * QVector3D(0, 0, distance);
    QVector3D cameraUpDirection = cameraTransformation * QVector3D(0, 1, 0);

    vMatrix.lookAt(cameraPosition, QVector3D(0, 0, 0), cameraUpDirection);

    //! [6]
    shaderProgram.bind();

    shaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);

    shaderProgram.setUniformValue("texture", 0);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture);
    glActiveTexture(0);

    shaderProgram.setAttributeArray("vertex", vertices.constData());
    shaderProgram.enableAttributeArray("vertex");

    shaderProgram.setAttributeArray("textureCoordinate", textureCoordinates.constData());
    shaderProgram.enableAttributeArray("textureCoordinate");

    glDrawArrays(GL_TRIANGLES, 0, vertices.size());

    shaderProgram.disableAttributeArray("vertex");

    shaderProgram.disableAttributeArray("textureCoordinate");

    shaderProgram.release();
}
//! [6]

void GlWidget::mousePressEvent(QMouseEvent *event)
{
    lastMousePosition = event->pos();

    event->accept();
}

void GlWidget::mouseMoveEvent(QMouseEvent *event)
{
    int deltaX = event->x() - lastMousePosition.x();
    int deltaY = event->y() - lastMousePosition.y();

    if (event->buttons() & Qt::LeftButton) {
        alpha -= deltaX;
        while (alpha < 0) {
            alpha += 360;
        }
        while (alpha >= 360) {
            alpha -= 360;
        }

        beta -= deltaY;
        if (beta < -90) {
            beta = -90;
        }
        if (beta > 90) {
            beta = 90;
        }

        updateGL();
    }

    lastMousePosition = event->pos();

    event->accept();
}

void GlWidget::wheelEvent(QWheelEvent *event)
{
    int delta = event->delta();

    if (event->orientation() == Qt::Vertical) {
        if (delta < 0) {
            distance *= 1.1;
        } else if (delta > 0) {
            distance *= 0.9;
        }

        updateGL();
    }

    event->accept();
}