qt5base-lts/examples/opengl/hellogl_es/glwindow.cpp

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#include "glwindow.h"

#include <QGuiApplication>
#include <QScreen>
#include <QTimer>

#include <math.h>
#include <stdio.h>

inline void CrossProduct(qreal &xOut, qreal &yOut, qreal &zOut, qreal x1, qreal y1, qreal z1, qreal x2, qreal y2, qreal z2)
{
   xOut = y1 * z2 - z1 * y2;
   yOut = z1 * x2 - x1 * z2;
   zOut = x1 * y2 - y1 * x2;
}

inline void Normalize(qreal &x, qreal &y, qreal &z)
{
    qreal l = sqrt(x*x + y*y + z*z);
    x = x / l;
    y = y / l;
    z = z / l;
}

GLWindow::GLWindow()
{
    setSurfaceType(OpenGLSurface);

    qtLogo = true;
    createdVertices = 0;
    createdNormals = 0;
    m_vertexNumber = 0;
    frames = 0;

    m_fScale = 1;

    QSurfaceFormat format;
    format.setDepthBufferSize(24);
    format.setMajorVersion(1);
    format.setMinorVersion(1);

    setGeometry(QGuiApplication::primaryScreen()->availableGeometry());
    setFormat(format);
    create();

    m_context = new QOpenGLContext;
    m_context->setFormat(format);
    m_context->create();

    m_context->makeCurrent(this);
    initializeGL();

    QTimer *timer = new QTimer(this);
    timer->setInterval(16);
    connect(timer, SIGNAL(timeout()), this, SLOT(paintGL()));
    timer->start();
}

GLWindow::~GLWindow()
{
  if (createdVertices)
      delete[] createdVertices;
  if (createdNormals)
      delete[] createdNormals;

  delete m_context;
}

void GLWindow::paintQtLogo()
{
    glDisable(GL_TEXTURE_2D);
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3,GL_FLOAT,0, createdVertices);
    glEnableClientState(GL_NORMAL_ARRAY);
    glNormalPointer(GL_FLOAT,0,createdNormals);
    glDrawArrays(GL_TRIANGLES, 0, m_vertexNumber / 3);
}

void GLWindow::initializeGL ()
{
    glClearColor(0.1f, 0.1f, 0.2f, 1.0f);

    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);

    GLfloat aLightPosition[] = {0.0f,0.3f,1.0f,0.0f};

    glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, aLightPosition);
    m_fAngle = 0;
    m_fScale = 1;
    createGeometry();
}

void GLWindow::paintGL()
{
    m_context->makeCurrent(this);

    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();

    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glMatrixMode(GL_TEXTURE);
    glPushMatrix();

    //Since OpenGL ES does not support glPush/PopAttrib(GL_ALL_ATTRIB_BITS)
    //we have to take care of the states ourselves

    glClearColor(0.1f, 0.1f, 0.2f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glEnable(GL_TEXTURE_2D);

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);

    glShadeModel(GL_FLAT);
    glFrontFace(GL_CW);
    glCullFace(GL_FRONT);
    glEnable(GL_CULL_FACE);
    glEnable(GL_DEPTH_TEST);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glRotatef(m_fAngle, 0.0f, 1.0f, 0.0f);
    glRotatef(m_fAngle, 1.0f, 0.0f, 0.0f);
    glRotatef(m_fAngle, 0.0f, 0.0f, 1.0f);
    glScalef(m_fScale, m_fScale,m_fScale);
    glTranslatef(0.0f,-0.2f,0.0f);

    GLfloat matDiff[] = {0.40f, 1.0f, 0.0f, 1.0f};
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiff);

    paintQtLogo();

    glMatrixMode(GL_MODELVIEW);
    glPopMatrix();
    glMatrixMode(GL_PROJECTION);
    glPopMatrix();
    glMatrixMode(GL_TEXTURE);
    glPopMatrix();

    glDisable(GL_LIGHTING);
    glDisable(GL_LIGHT0);

    glDisable(GL_DEPTH_TEST);
    glDisable(GL_CULL_FACE);

    m_context->swapBuffers(this);

    m_fAngle += 1.0f;
}

void GLWindow::createGeometry()
{
    vertices.clear();
    normals.clear();

    qreal x1 = +0.06f;
    qreal y1 = -0.14f;
    qreal x2 = +0.14f;
    qreal y2 = -0.06f;
    qreal x3 = +0.08f;
    qreal y3 = +0.00f;
    qreal x4 = +0.30f;
    qreal y4 = +0.22f;

    quad(x1, y1, x2, y2, y2, x2, y1, x1);
    quad(x3, y3, x4, y4, y4, x4, y3, x3);

    extrude(x1, y1, x2, y2);
    extrude(x2, y2, y2, x2);
    extrude(y2, x2, y1, x1);
    extrude(y1, x1, x1, y1);
    extrude(x3, y3, x4, y4);
    extrude(x4, y4, y4, x4);
    extrude(y4, x4, y3, x3);

    const qreal Pi = 3.14159f;
    const int NumSectors = 100;

    for (int i = 0; i < NumSectors; ++i) {
        qreal angle1 = (i * 2 * Pi) / NumSectors;
        qreal x5 = 0.30 * sin(angle1);
        qreal y5 = 0.30 * cos(angle1);
        qreal x6 = 0.20 * sin(angle1);
        qreal y6 = 0.20 * cos(angle1);

        qreal angle2 = ((i + 1) * 2 * Pi) / NumSectors;
        qreal x7 = 0.20 * sin(angle2);
        qreal y7 = 0.20 * cos(angle2);
        qreal x8 = 0.30 * sin(angle2);
        qreal y8 = 0.30 * cos(angle2);

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

        extrude(x6, y6, x7, y7);
        extrude(x8, y8, x5, y5);
    }

    m_vertexNumber = vertices.size();
    createdVertices = new GLfloat[m_vertexNumber];
    createdNormals = new GLfloat[m_vertexNumber];
    for (int i = 0;i < m_vertexNumber;i++) {
      createdVertices[i] = vertices.at(i) * 2;
      createdNormals[i] = normals.at(i);
    }
    vertices.clear();
    normals.clear();
}

void GLWindow::quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4)
{
    qreal nx, ny, nz;

    vertices << x1 << y1 << -0.05f;
    vertices << x2 << y2 << -0.05f;
    vertices << x4 << y4 << -0.05f;

    vertices << x3 << y3 << -0.05f;
    vertices << x4 << y4 << -0.05f;
    vertices << x2 << y2 << -0.05f;

    CrossProduct(nx, ny, nz, x2 - x1, y2 - y1, 0, x4 - x1, y4 - y1, 0);
    Normalize(nx, ny, nz);

    normals << nx << ny << nz;
    normals << nx << ny << nz;
    normals << nx << ny << nz;

    normals << nx << ny << nz;
    normals << nx << ny << nz;
    normals << nx << ny << nz;

    vertices << x4 << y4 << 0.05f;
    vertices << x2 << y2 << 0.05f;
    vertices << x1 << y1 << 0.05f;

    vertices << x2 << y2 << 0.05f;
    vertices << x4 << y4 << 0.05f;
    vertices << x3 << y3 << 0.05f;

    CrossProduct(nx, ny, nz, x2 - x4, y2 - y4, 0, x1 - x4, y1 - y4, 0);
    Normalize(nx, ny, nz);

    normals << nx << ny << nz;
    normals << nx << ny << nz;
    normals << nx << ny << nz;

    normals << nx << ny << nz;
    normals << nx << ny << nz;
    normals << nx << ny << nz;
}

void GLWindow::extrude(qreal x1, qreal y1, qreal x2, qreal y2)
{
    qreal nx, ny, nz;

    vertices << x1 << y1 << +0.05f;
    vertices << x2 << y2 << +0.05f;
    vertices << x1 << y1 << -0.05f;

    vertices << x2 << y2 << -0.05f;
    vertices << x1 << y1 << -0.05f;
    vertices << x2 << y2 << +0.05f;

    CrossProduct(nx, ny, nz, x2 - x1, y2 - y1, 0.0f, 0.0f, 0.0f, -0.1f);
    Normalize(nx, ny, nz);

    normals << nx << ny << nz;
    normals << nx << ny << nz;
    normals << nx << ny << nz;

    normals << nx << ny << nz;
    normals << nx << ny << nz;
    normals << nx << ny << nz;
}