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

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

 This file is part of the QGLViewer library version 2.6.2.

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

#include <QGLViewer/manipulatedFrame.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
  Vec pos1 = light1->position();
  pos[0] = float(pos1.x);
  pos[1] = float(pos1.y);
  pos[2] = float(pos1.z);
  glLightfv(GL_LIGHT1, GL_POSITION, pos);
  glLightfv(GL_LIGHT1, GL_SPOT_DIRECTION, light1->inverseTransformOf(Vec(0,0,1)));

  // Point light
  Vec pos2 = light2->position();
  pos[0] = float(pos2.x);
  pos[1] = float(pos2.y);
  pos[2] = float(pos2.z);
  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, 0.2f , 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, 1.2f);
  else
	drawLight(GL_LIGHT1);

  if (light2->grabsMouse())
	drawLight(GL_LIGHT2, 1.2f);
  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]  = {0.8f, 0.2f, 0.2f, 1.0};
  const GLfloat light_diffuse[4]  = {1.0, 0.4f, 0.4f, 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]  = {0.2f, 0.2f, 2.0, 1.0};
  const GLfloat light_diffuse2[4]  = {0.8f, 0.8f, 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;
}
