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

 Copyright (C) 2002-2014 Gilles Debunne. All rights reserved.

 This file is part of the QGLViewer library version 2.8.0.

 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 "anaglyph.h"

using namespace qglviewer;
using namespace std;

void Viewer::draw() {
  static const bool left = true;

  // Draw for left eye
  camera()->loadProjectionMatrixStereo(left);
  camera()->loadModelViewMatrixStereo(left);
  glColor3f(0.0, 0.0, 1.0);
  drawScene();

  // Draw for right eye
  camera()->loadProjectionMatrixStereo(!left);
  camera()->loadModelViewMatrixStereo(!left);
  glColor3f(1.0, 0.0, 0.0);
  drawScene();
}

// Draws a spiral, without changing color
void Viewer::drawScene() {
  const float nbSteps = 200.0;

  glBegin(GL_QUAD_STRIP);
  for (float i = 0; i < nbSteps; ++i) {
    float ratio = i / nbSteps;
    float angle = 21.0 * ratio;
    float c = cos(angle);
    float s = sin(angle);
    float r1 = 1.0 - 0.8 * ratio;
    float r2 = 0.8 - 0.8 * ratio;
    float alt = ratio - 0.5;
    const float nor = .5;
    const float up = sqrt(1.0 - nor * nor);
    glNormal3f(nor * c, up, nor * s);
    glVertex3f(r1 * c, alt, r1 * s);
    glVertex3f(r2 * c, alt + 0.05, r2 * s);
  }
  glEnd();
}

void Viewer::init() {
  // Wireframe display is needed to prevent occlusions
  // between left and right images.
  glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

  // Restore previous viewer state.
  restoreStateFromFile();

  help();
}

QString Viewer::helpString() const {
  QString text("<h2>A n a g l y p h</h2>");
  text += "The anaglyph stereo mode displays simultaneously two colored views "
          "of the scene.<br><br>";
  text += "You need to wear glasses with colored lenses (here red and blue) to "
          "view the stereo image";
  text += "Each eye then sees the associated view, creating the stereo "
          "illusion.<br><br>";
  text += "Stereo is best perceived when viewer is full screen "
          "(<code>Alt+Enter</code>).<br><br>";
  text += "Simply use the <i>loadModelViewMatrixStereo()</i> and";
  text +=
      "<i>loadProjectionMatrixStereo()</i> camera functions to set appropriate";
  text += "<i>GL_MODELVIEW</i> and <i>GL_PROJECTION</i> stereo matrices.";
  return text;
}
