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

 Copyright (C) 2002-2006 Gilles Debunne (Gilles.Debunne@imag.fr)

This file is part of the QGLViewer library.
 Version 2.2.4-1, released on December 12, 2006.

 http://artis.imag.fr/Members/Gilles.Debunne/QGLViewer

 libQGLViewer is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 libQGLViewer is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with libQGLViewer; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

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

#include "drawLight.h"
#include <math.h>

using namespace std;
using namespace qglviewer;

void Viewer::draw()
{
  float pos[4] = {1.0, 0.5, 1.0, 0.0};
  // Directionnal light
  glLightfv(GL_LIGHT0, GL_POSITION, pos);

  pos[3] = 1.0;
  // Spot light
  light1->getPosition(pos[0], pos[1], pos[2]);
  glLightfv(GL_LIGHT1, GL_POSITION, pos);
  glLightfv(GL_LIGHT1, GL_SPOT_DIRECTION, light1->inverseTransformOf(Vec(0,0,1)));

  // Point light
  light2->getPosition(pos[0], pos[1], pos[2]);
  glLightfv(GL_LIGHT2, GL_POSITION, pos);

  // Draws the spiral
  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);
      glColor3f(1-ratio, .2 , ratio);
      glNormal3f(nor*c, up, nor*s);
      glVertex3f(r1*c, alt, r1*s);
      glVertex3f(r2*c, alt+0.05, r2*s);
    }
  glEnd();

  drawLight(GL_LIGHT0);

  if (light1->grabsMouse())
    drawLight(GL_LIGHT1, 1.2);
  else
    drawLight(GL_LIGHT1);

  if (light2->grabsMouse())
    drawLight(GL_LIGHT2, 1.2);
  else
    drawLight(GL_LIGHT2);
}


void Viewer::init()
{
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  // Light0 is the default ambient light
  glEnable(GL_LIGHT0);

  // Light1 is a spot light
  glEnable(GL_LIGHT1);
  const GLfloat light_ambient[4]  = {0.8, 0.2, 0.2, 1.0};
  const GLfloat light_diffuse[4]  = {1.0, 0.4, 0.4, 1.0};
  const GLfloat light_specular[4] = {1.0, 0.0, 0.0, 1.0};

  glLightf( GL_LIGHT1, GL_SPOT_EXPONENT,  3.0);
  glLightf( GL_LIGHT1, GL_SPOT_CUTOFF,    20.0);
  glLightf( GL_LIGHT1, GL_CONSTANT_ATTENUATION, 0.5);
  glLightf( GL_LIGHT1, GL_LINEAR_ATTENUATION, 1.0);
  glLightf( GL_LIGHT1, GL_QUADRATIC_ATTENUATION, 1.5);
  glLightfv(GL_LIGHT1, GL_AMBIENT,  light_ambient);
  glLightfv(GL_LIGHT1, GL_SPECULAR, light_specular);
  glLightfv(GL_LIGHT1, GL_DIFFUSE,  light_diffuse);

  // Light2 is a classical directionnal light
  glEnable(GL_LIGHT2);
  const GLfloat light_ambient2[4]  = {0.2, 0.2, 2.0, 1.0};
  const GLfloat light_diffuse2[4]  = {0.8, 0.8, 1.0, 1.0};
  const GLfloat light_specular2[4] = {0.0, 0.0, 1.0, 1.0};

  glLightfv(GL_LIGHT2, GL_AMBIENT,  light_ambient2);
  glLightfv(GL_LIGHT2, GL_SPECULAR, light_specular2);
  glLightfv(GL_LIGHT2, GL_DIFFUSE,  light_diffuse2);

  light1 = new ManipulatedFrame();
  light2 = new ManipulatedFrame();
  setMouseTracking(true);

  light1->setPosition(0.5, 0.5, 0);
  // Align z axis with -position direction : look at scene center
  light1->setOrientation(Quaternion(Vec(0,0,1), -light1->position()));

  light2->setPosition(-0.5, 0.5, 0);

  restoreStateFromFile();
  help();
}

QString Viewer::helpString() const
{
  QString text("<h2>D r a w L i g h t</h2>");
  text += "The <i>drawLight()</i> function displays a representation of the OpenGL lights ";
  text += "of your scene. This is convenient for debugging your light setup.<br><br>";
  text += "This scene features a directionnal ligth (arrow), a spot light (cone) and a point ";
  text += "light source (sphere). The representation color, position and shape matches the light setup.<br><br>";
  text += "Hover over the point light or the spot light to manipulate it using the mouse (right ";
  text += "button translates and left button rotates).";
  return text;
}