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#include "glwidget.h"

#include <math.h>

#ifndef GL_MULTISAMPLE

#define GL_MULTISAMPLE  0x809D

#endif

GLWidget::GLWidget(QWidget *parent)

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

{

    startTimer(40);

    setWindowTitle(tr("Sample Buffers"));

}

void GLWidget::initializeGL()

{

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    glOrtho(-.5, .5, .5, -.5, -1000, 1000);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

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

    makeObject();

}

void GLWidget::resizeGL(int w, int h)

{

    glViewport(0, 0, w, h);

}

void GLWidget::paintGL()

{

    static float rot = 0.0;

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);

    glPushMatrix();

    glEnable(GL_MULTISAMPLE);

    glTranslatef(-0.25f, -0.10f, 0.0f);

    glScalef(0.75f, 1.15f, 0.0f);

    glRotatef(rot, 0.0f, 0.f, 1.0f);

    glCallList(list);

    glPopMatrix();

    glPushMatrix();

    glDisable(GL_MULTISAMPLE);

    glTranslatef(0.25f, -0.10f, 0.0f);

    glScalef(0.75f, 1.15f, 0.0f);

    glRotatef(rot, 0.0f, 0.0f, 1.0f);

    glCallList(list);

    glPopMatrix();

    rot += 0.2f;

    qglColor(Qt::black);

    renderText(-0.35, 0.4, 0.0, "Multisampling enabled");

    renderText(0.15, 0.4, 0.0, "Multisampling disabled");

}

void GLWidget::timerEvent(QTimerEvent *)

{

    update();

}

void GLWidget::makeObject()

{

    QColor qtGreen(QColor::fromCmykF(0.40, 0.0, 1.0, 0.0));

    const double Pi = 3.14159265358979323846;

    const int NumSectors = 15;

    GLdouble x1 = +0.06;

    GLdouble y1 = -0.14;

    GLdouble x2 = +0.14;

    GLdouble y2 = -0.06;

    GLdouble x3 = +0.08;

    GLdouble y3 = +0.00;

    GLdouble x4 = +0.30;

    GLdouble y4 = +0.22;

    list = glGenLists(1);

    glNewList(list, GL_COMPILE);

    {

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

            double angle1 = (i * 2 * Pi) / NumSectors;

            GLdouble x5 = 0.30 * sin(angle1);

            GLdouble y5 = 0.30 * cos(angle1);

            GLdouble x6 = 0.20 * sin(angle1);

            GLdouble y6 = 0.20 * cos(angle1);

            double angle2 = ((i + 1) * 2 * Pi) / NumSectors;

            GLdouble x7 = 0.20 * sin(angle2);

            GLdouble y7 = 0.20 * cos(angle2);

            GLdouble x8 = 0.30 * sin(angle2);

            GLdouble y8 = 0.30 * cos(angle2);

            qglColor(qtGreen);

            quad(GL_QUADS, x5, y5, x6, y6, x7, y7, x8, y8);

            qglColor(Qt::black);

            quad(GL_LINE_LOOP, x5, y5, x6, y6, x7, y7, x8, y8);

        }

        qglColor(qtGreen);

        quad(GL_QUADS, x1, y1, x2, y2, y2, x2, y1, x1);

        quad(GL_QUADS, x3, y3, x4, y4, y4, x4, y3, x3);

        qglColor(Qt::black);

        quad(GL_LINE_LOOP, x1, y1, x2, y2, y2, x2, y1, x1);

        quad(GL_LINE_LOOP, x3, y3, x4, y4, y4, x4, y3, x3);

    }

    glEndList();

}

void GLWidget::quad(GLenum primitive, GLdouble x1, GLdouble y1, GLdouble x2, GLdouble y2,

                    GLdouble x3, GLdouble y3, GLdouble x4, GLdouble y4)

{

    glBegin(primitive);

    {

        glVertex2d(x1, y1);

        glVertex2d(x2, y2);

        glVertex2d(x3, y3);

        glVertex2d(x4, y4);

    }

    glEnd();

}