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

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** contained in the Technology Preview License Agreement accompanying

** this package.

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** Foundation and appearing in the file LICENSE.LGPL included in the

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

#include <QtGui>

#include <QtOpenGL>

#include "glwidget.h"

GLWidget::GLWidget(QWidget *parent, QGLWidget *shareWidget)

    : QGLWidget(parent, shareWidget)

{

    clearColor = Qt::black;

    xRot = 0;

    yRot = 0;

    zRot = 0;

#ifdef QT_OPENGL_ES_2

    program = 0;

#endif

}

GLWidget::~GLWidget()

{

}

QSize GLWidget::minimumSizeHint() const

{

    return QSize(50, 50);

}

QSize GLWidget::sizeHint() const

{

    return QSize(200, 200);

}

void GLWidget::rotateBy(int xAngle, int yAngle, int zAngle)

{

    xRot += xAngle;

    yRot += yAngle;

    zRot += zAngle;

    updateGL();

}

void GLWidget::setClearColor(const QColor &color)

{

    clearColor = color;

    updateGL();

}

void GLWidget::initializeGL()

{

    makeObject();

    glEnable(GL_DEPTH_TEST);

    glEnable(GL_CULL_FACE);

#ifndef QT_OPENGL_ES_2

    glEnable(GL_TEXTURE_2D);

#endif

#ifdef QT_OPENGL_ES_2

#define PROGRAM_VERTEX_ATTRIBUTE 0

#define PROGRAM_TEXCOORD_ATTRIBUTE 1

    QGLShader *vshader = new QGLShader(QGLShader::VertexShader, this);

    const char *vsrc =

        "attribute highp vec4 vertex;\n"

        "attribute mediump vec4 texCoord;\n"

        "varying mediump vec4 texc;\n"

        "uniform mediump mat4 matrix;\n"

        "void main(void)\n"

        "{\n"

        "    gl_Position = matrix * vertex;\n"

        "    texc = texCoord;\n"

        "}\n";

    vshader->compile(vsrc);

    QGLShader *fshader = new QGLShader(QGLShader::FragmentShader, this);

    const char *fsrc =

        "uniform sampler2D texture;\n"

        "varying mediump vec4 texc;\n"

        "void main(void)\n"

        "{\n"

        "    gl_FragColor = texture2D(texture, texc.st);\n"

        "}\n";

    fshader->compile(fsrc);

    program = new QGLShaderProgram(this);

    program->addShader(vshader);

    program->addShader(fshader);

    program->bindAttributeLocation("vertex", PROGRAM_VERTEX_ATTRIBUTE);

    program->bindAttributeLocation("texCoord", PROGRAM_TEXCOORD_ATTRIBUTE);

    program->link();

    program->enable();

    program->setUniformValue("texture", 0);

#endif

}

void GLWidget::paintGL()

{

    qglClearColor(clearColor);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

#if !defined(QT_OPENGL_ES_2)

    glLoadIdentity();

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

    glRotatef(xRot / 16.0f, 1.0f, 0.0f, 0.0f);

    glRotatef(yRot / 16.0f, 0.0f, 1.0f, 0.0f);

    glRotatef(zRot / 16.0f, 0.0f, 0.0f, 1.0f);

    glVertexPointer(3, GL_FLOAT, 0, vertices.constData());

    glTexCoordPointer(2, GL_FLOAT, 0, texCoords.constData());

    glEnableClientState(GL_VERTEX_ARRAY);

    glEnableClientState(GL_TEXTURE_COORD_ARRAY);

#else

    QMatrix4x4 m;

    m.ortho(-0.5f, +0.5f, +0.5f, -0.5f, 4.0f, 15.0f);

    m.translate(0.0f, 0.0f, -10.0f);

    m.rotate(xRot / 16.0f, 1.0f, 0.0f, 0.0f);

    m.rotate(yRot / 16.0f, 0.0f, 1.0f, 0.0f);

    m.rotate(zRot / 16.0f, 0.0f, 0.0f, 1.0f);

    program->setUniformValue("matrix", m);

    program->setAttributeArray

        (PROGRAM_VERTEX_ATTRIBUTE, vertices.constData());

    program->setAttributeArray

        (PROGRAM_TEXCOORD_ATTRIBUTE, texCoords.constData());

#endif

    for (int i = 0; i < 6; ++i) {

        glBindTexture(GL_TEXTURE_2D, textures[i]);

        glDrawArrays(GL_TRIANGLE_FAN, i * 4, 4);

    }

}

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

{

    int side = qMin(width, height);

    glViewport((width - side) / 2, (height - side) / 2, side, side);

#if !defined(QT_OPENGL_ES_2)

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

#ifndef QT_OPENGL_ES

    glOrtho(-0.5, +0.5, +0.5, -0.5, 4.0, 15.0);

#else

    glOrthof(-0.5, +0.5, +0.5, -0.5, 4.0, 15.0);

#endif

    glMatrixMode(GL_MODELVIEW);

#endif

}

void GLWidget::mousePressEvent(QMouseEvent *event)

{

    lastPos = event->pos();

}

void GLWidget::mouseMoveEvent(QMouseEvent *event)

{

    int dx = event->x() - lastPos.x();

    int dy = event->y() - lastPos.y();

    if (event->buttons() & Qt::LeftButton) {

        rotateBy(8 * dy, 8 * dx, 0);

    } else if (event->buttons() & Qt::RightButton) {

        rotateBy(8 * dy, 0, 8 * dx);

    }

    lastPos = event->pos();

}

void GLWidget::mouseReleaseEvent(QMouseEvent * /* event */)

{

    emit clicked();

}

void GLWidget::makeObject()

{

    static const int coords[6][4][3] = {

        { { +1, -1, -1 }, { -1, -1, -1 }, { -1, +1, -1 }, { +1, +1, -1 } },

        { { +1, +1, -1 }, { -1, +1, -1 }, { -1, +1, +1 }, { +1, +1, +1 } },

        { { +1, -1, +1 }, { +1, -1, -1 }, { +1, +1, -1 }, { +1, +1, +1 } },

        { { -1, -1, -1 }, { -1, -1, +1 }, { -1, +1, +1 }, { -1, +1, -1 } },

        { { +1, -1, +1 }, { -1, -1, +1 }, { -1, -1, -1 }, { +1, -1, -1 } },

        { { -1, -1, +1 }, { +1, -1, +1 }, { +1, +1, +1 }, { -1, +1, +1 } }

    };

    for (int j=0; j < 6; ++j) {

        textures[j] = bindTexture

            (QPixmap(QString(":/images/side%1.png").arg(j + 1)), GL_TEXTURE_2D);

    }

    for (int i = 0; i < 6; ++i) {

        for (int j = 0; j < 4; ++j) {

            texCoords.append

                (QVector2D(j == 0 || j == 3, j == 0 || j == 1));

            vertices.append

                (QVector3D(0.2 * coords[i][j][0], 0.2 * coords[i][j][1],

                           0.2 * coords[i][j][2]));

        }

    }

}