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

   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 "cameraLight.h"

using namespace std;
using namespace qglviewer;

void Viewer::draw()
{
  // Place light at camera position
  const Vec cameraPos = camera()->position();
  const GLfloat pos[4] = { cameraPos[0], cameraPos[1], cameraPos[2], 1.0 };
  glLightfv(GL_LIGHT1, GL_POSITION, pos);

  // Orientate light along view direction
  glLightfv(GL_LIGHT1, GL_SPOT_DIRECTION, camera()->viewDirection());

  drawSpiral();
}

// Draws a spiral
void Viewer::drawSpiral()
{
  const float nbSteps = 1000.0;

  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()
{
  // Light setup
  glDisable(GL_LIGHT0);
  glEnable(GL_LIGHT1);

  // Light default parameters
  const GLfloat light_ambient[4] = { 1.0, 1.0, 1.0, 1.0 };
  const GLfloat light_specular[4] = { 1.0, 1.0, 1.0, 1.0 };
  const GLfloat light_diffuse[4] = { 1.0, 1.0, 1.0, 1.0 };

  glLightf(GL_LIGHT1, GL_SPOT_EXPONENT, 3.0);
  glLightf(GL_LIGHT1, GL_SPOT_CUTOFF, 10.0);
  glLightf(GL_LIGHT1, GL_CONSTANT_ATTENUATION, 0.1f);
  glLightf(GL_LIGHT1, GL_LINEAR_ATTENUATION, 0.3f);
  glLightf(GL_LIGHT1, GL_QUADRATIC_ATTENUATION, 0.3f);
  glLightfv(GL_LIGHT1, GL_AMBIENT, light_ambient);
  glLightfv(GL_LIGHT1, GL_SPECULAR, light_specular);
  glLightfv(GL_LIGHT1, GL_DIFFUSE, light_diffuse);

  // Restore previous viewer state.
  restoreStateFromFile();

  // Opens help window
  help();
}

QString Viewer::helpString() const
{
  QString text("<h2>C a m e r a L i g h t</h2>");
  text += "See the <b>Mouse</b> tab and the documentation web pages for details.<br><br>";
  text += "Press <b>Escape</b> to exit the viewer.";
  return text;
}
