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

   Copyright (C) 2002-2008 Gilles Debunne. All rights reserved.

   This file is part of the QGLViewer library version 2.3.5.

   http://www.libqglviewer.com - contact@libqglviewer.com

   This file may be used under the terms of the GNU General Public License
   versions 2.0 or 3.0 as published by the Free Software Foundation and
   appearing in the LICENSE file included in the packaging of this file.
   In addition, as a special exception, Gilles Debunne gives you certain
   additional rights, described in the file GPL_EXCEPTION in this package.

   libQGLViewer uses dual licensing. Commercial/proprietary software must
   purchase a libQGLViewer Commercial License.

   This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
   WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

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

#include "viewer.h"

#include <QPainter>

using namespace std;

#ifndef GL_MULTISAMPLE
#  define GL_MULTISAMPLE 0x809D
#endif

Viewer::Viewer(QWidget* parent)
  : QGLViewer(QGLFormat(QGL::SampleBuffers), parent)
{
  setAttribute(Qt::WA_NoSystemBackground);
}

void Viewer::drawOverpaint(QPainter* painter)
{
  painter->save();
  painter->translate(width() / 2, height() / 2);
  QRadialGradient radialGrad(QPointF(-40, -40), 100);
  radialGrad.setColorAt(0, QColor(255, 255, 255, 100));
  radialGrad.setColorAt(1, QColor(200, 200, 0, 100));
  painter->setBrush(QBrush(radialGrad));
  painter->drawRoundRect(-100, -100, 200, 200);
  painter->restore();
}

// Draws a spiral
void Viewer::draw()
{
  const float nbSteps = 200.0;

  glBegin(GL_QUAD_STRIP);
  for(int i = 0; i < nbSteps; ++i) {
    const float ratio = i / nbSteps;
    const float angle = 21.0 * ratio;
    const float c = cos(angle);
    const float s = sin(angle);
    const float r1 = 1.0 - 0.8f * ratio;
    const float r2 = 0.8f - 0.8f * ratio;
    const float alt = ratio - 0.5f;
    const float nor = 0.5f;
    const float up = sqrt(1.0 - nor * nor);
    glColor3f(1.0 - ratio, 0.2f, ratio);
    glNormal3f(nor * c, up, nor * s);
    glVertex3f(r1 * c, alt, r1 * s);
    glVertex3f(r2 * c, alt + 0.05f, r2 * s);
  }
  glEnd();
}

void Viewer::init()
{
  restoreStateFromFile();
  help();
}

void Viewer::paintEvent(QPaintEvent* event)
{
  Q_UNUSED(event)
  QPainter painter;
  painter.begin(this);
  painter.setRenderHint(QPainter::Antialiasing);

  // Save current OpenGL state
  glPushAttrib(GL_ALL_ATTRIB_BITS);
  glMatrixMode(GL_PROJECTION);
  glPushMatrix();
  glMatrixMode(GL_MODELVIEW);
  glPushMatrix();

  // Reset OpenGL parameters
  glShadeModel(GL_SMOOTH);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_CULL_FACE);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_MULTISAMPLE);
  static GLfloat lightPosition[4] = { 1.0, 5.0, 5.0, 1.0 };
  glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
  qglClearColor(backgroundColor());

  // Classical 3D drawing, usually performed by paintGL().
  preDraw();
  draw();
  postDraw();
  // Restore OpenGL state
  glMatrixMode(GL_MODELVIEW);
  glPopMatrix();
  glMatrixMode(GL_PROJECTION);
  glPopMatrix();
  glPopAttrib();

  drawOverpaint(&painter);

  painter.end();
}

QString Viewer::helpString() const
{
  QString text("<h2>O v e r p a i n t</h2>");
  text += "This example shows how to mix the 2D QPainter drawing with regular 3D in an OpenGL QGLViewer.<br>";
  text += "The <code>paintEvent</code> method is overloaded to interleave the two drawing codes.";
  return text;
}
