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

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

 This file is part of the QGLViewer library version 2.3.1.

 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 "select.h"
#include <qmessagebox.h>
#include <math.h>

using namespace std;

static void drawSpiral(const bool specialColor = false)
{
  const float nbSteps = 100.0;
  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 = 0.5 - 0.3*ratio;
      float r2 = 0.3 - 0.3*ratio;
      float alt = ratio - 0.5;
      const float nor = .5;
      const float up = sqrt(1.0-nor*nor);
      if (specialColor)
	glColor3f(1.0-ratio, 0.8f , ratio/2.0);
      else
	glColor3f(1.0-ratio, 0.2f, ratio);
      glNormal3f(nor*c, nor*s, up);
      glVertex3f(r2*c, r2*s, alt+0.05f);
      glVertex3f(r1*c, r1*s, alt);
    }
  glEnd();
}

void Viewer::drawWithNames()
{
  // Draw spirals, pushing a name (id) for each of them
  const int nb = 10;
  for (int i=0; i<nb; ++i)
    {
      glPushMatrix();
      glTranslatef(cos(2.0*i*M_PI/nb), sin(2.0*i*M_PI/nb), 0.);

      glPushName(i);
      drawSpiral();
      glPopName();

      glPopMatrix();
    }
}

void Viewer::postSelection(const QPoint& point)
{
  // Compute orig and dir, used to draw a representation of the intersecting line
  camera()->convertClickToLine(point, orig, dir);

  // Find the selectedPoint coordinates, using camera()->pointUnderPixel().
  bool found;
  selectedPoint = camera()->pointUnderPixel(point, found);
  selectedPoint -= 0.01f*dir; // Small offset to make point clearly visible.
  // Note that "found" is different from (selectedObjectId()>=0) because of the size of the select region.

  if (selectedName() == -1)
    QMessageBox::information(this, "No selection",
			     "No object selected under pixel " + QString::number(point.x()) + "," + QString::number(point.y()));
  else
    QMessageBox::information(this, "Selection",
			     "Spiral number " + QString::number(selectedName()) + " selected under pixel " +
			     QString::number(point.x()) + "," + QString::number(point.y()));
}

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

  glLineWidth(3.0);
  glPointSize(10.0);

  help();
}

void Viewer::draw()
{
  // Draw ten spirals
  const int nb = 10;
  for (int i=0; i<nb; ++i)
    {
      glPushMatrix();
      glTranslatef(cos(2.0*i*M_PI/nb), sin(2.0*i*M_PI/nb), 0.0);
      drawSpiral(i == selectedName());
      glPopMatrix();
    }

  // Draw the intersection line
  glBegin(GL_LINES);
  glVertex3fv(orig);
  glVertex3fv(orig + 100.0*dir);
  glEnd();

  // Draw (approximated) intersection point on selected object
  if (selectedName() >= 0)
    {
      glColor3f(0.9f, 0.2f, 0.1f);
      glBegin(GL_POINTS);
      glVertex3fv(selectedPoint);
      glEnd();
    }
}

QString Viewer::helpString() const
{
  QString text("<h2>S e l e c t</h2>");
  text += "Left click while pressing the <b>Shift</b> key to select an object of the scene.<br><br>";
  text += "A line is drawn between the selected point and the camera selection position. ";
  text += "using <i>convertClickToLine()</i>, a useful function for analytical intersections.<br><br>";
  text += "To add object selection in your viewer, all you need to do is to define the <i>drawWithNames</i> function. ";
  text += "It gives a name to each selectable object and selection is then performed using the OpenGL <i>GL_SELECT</i> render mode.<br><br>";
  text += "Feel free to cut and paste this implementation in your own applications.";
  return text;
}