screensaver.cpp

#include "screensaver.h"


QQuickFramebufferObject::Renderer *Screensaver::createRenderer() const
{
  return new StickRenderer();
}

StickRenderer::StickRenderer()
{

    _barSticks = QVector<Stick*>();

    for (int i = 0; i < 100; i++) {
      Stick *stick = new Stick;
      stick->setSize(0.00585366, 0.117073);
      stick->setColor("#FFFFFF");
      _barSticks.push_back(stick);
    }

    _timer.start();

    randomRadius = std::uniform_real_distribution<qreal>(-1, 1);
    randomFrequency = std::uniform_real_distribution<qreal>(0.01, 0.1);
    randomRatioRotation = std::uniform_real_distribution<qreal>(-0.1, 0.1);

    initializeGLCanvas();
}

void StickRenderer::initializeGLCanvas()
{
  initializeOpenGLFunctions();
  QSurfaceFormat format;
  format.setSamples(16);
  QOpenGLContext::currentContext()->setFormat(format);

  glEnable(GL_ALPHA_TEST);
  glEnable(GL_DEPTH_TEST);

  glEnable(GL_BLEND);
  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  glClearColor(0, 0, 0, 0);

}

void StickRenderer::resizeGLCanvas(int width, int height)
{
  glViewport(0, 0,width, height);

  qreal right = qreal(width) / qreal(height);
  qreal left = -right;
  qreal top = 1;
  qreal bottom = -top;

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  glMatrixMode(GL_MODELVIEW );
  glLoadIdentity();

  glOrtho(left, right, bottom, top, -1, 1);


  randomX = std::uniform_real_distribution<qreal>(left, right);
  randomY = std::uniform_real_distribution<qreal>(bottom, top);
}

void StickRenderer::paintGLCanvas()
{
  glClearColor(0, 0, 0, 0);
//  glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glUseProgram(0);

  QRandomGenerator generator;

  for (auto stick : _barSticks) {
    qreal centerX = randomX(generator);
    qreal centerY = randomY(generator);
    qreal radius = randomRadius(generator);
    qreal frequency = randomFrequency(generator);
    qreal ratioRotation = randomRatioRotation(generator);

    qreal timeNow = elapsed() / 1000.0;

    qreal posX = centerX + cos(timeNow * frequency) * radius;
    qreal posY = centerY + sin(timeNow * frequency) * radius;
    qreal rotation = (elapsed() + 10000) * frequency * ratioRotation;

    stick->setX(posX);
    stick->setY(posY);
    stick->setRotation(fmod(rotation, 360));

    stick->draw();
  }

  update();
}

void StickRenderer::render()
{
  paintGLCanvas();
}

QOpenGLFramebufferObject *StickRenderer::createFramebufferObject(const QSize &size)
{
  initializeGLCanvas();
  resizeGLCanvas(size.width(), size.height());

  QOpenGLFramebufferObjectFormat format;
  format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
  format.setSamples(16);

  return new QOpenGLFramebufferObject(size, format);
}

void StickRenderer::synchronize(QQuickFramebufferObject *item)
{
  Screensaver *screensaver = qobject_cast<Screensaver *>(item);

  screensaver->window()->resetOpenGLState();
  screensaver->window()->setClearBeforeRendering(true);
}