QtBaseViewerPicking.cc

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//=============================================================================
//
//  CLASS QtBaseViewer - IMPLEMENTATION
//
//=============================================================================


//== INCLUDES =================================================================

#include "QtBaseViewer.hh"
#include "QtGLGraphicsScene.hh"
#include "QtGLGraphicsView.hh"

//== NAMESPACES ===============================================================

namespace ACG {
namespace QtWidgets {

//== IMPLEMENTATION ==========================================================

static const unsigned int  SELECTION_BUFFER_SIZE = 10000;
static const unsigned int  NAME_STACK_SIZE       = 2;

//== IMPLEMENTATION ==========================================================


void QtBaseViewer::renderPicking(bool _renderPicking, ACG::SceneGraph::PickTarget _mode) {
  renderPicking_    = _renderPicking;
  pickRendererMode_ = _mode;
}

//-----------------------------------------------------------------------------


bool QtBaseViewer::pick( SceneGraph::PickTarget _pickTarget,
                         const QPoint&          _mousePos,
                         unsigned int&          _nodeIdx,
                         unsigned int&          _targetIdx,
                         Vec3d*                 _hitPointPtr )
{
  if (sceneGraphRoot_)
  {
    GLint         w = glWidth(),
                  h = glHeight(),
                  x = _mousePos.x(),
                  y = h - _mousePos.y();
    GLint         viewport[4] = {0,0,w,h};
    GLuint        nameBuffer[ NAME_STACK_SIZE ];

    // reduce stack usage
    std::vector<GLuint> selectionBuffer(SELECTION_BUFFER_SIZE);


    // Initialize name buffer
    nameBuffer[0] = 0;
    nameBuffer[1] = 0;

    const GLMatrixd&  modelview  = glstate_->modelview();
    const GLMatrixd&  projection = glstate_->projection();


    // prepare GL state
    makeCurrent();

    glSelectBuffer( SELECTION_BUFFER_SIZE, &selectionBuffer[0] );
    glRenderMode(GL_SELECT);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
//    gluPickMatrix((GLdouble) x, (GLdouble) y, 3, 3, viewport);
    // gluPickMatrix implementation as in mesa3d
    // Translate and scale the picked region to the entire window
    const float deltax = 3.0f, deltay = 3.0f;
    glTranslatef(float(viewport[2] - 2 * (x - viewport[0])) / deltax, 
      float(viewport[3] - 2 * (y - viewport[1])) / deltay, 0.0f);
    glScalef(viewport[2] / deltax, viewport[3] / deltay, 1.0);

    glMultMatrixd(projection.get_raw_data());
    glMatrixMode(GL_MODELVIEW);
    glLoadMatrixd(modelview.get_raw_data());
    ACG::GLState::disable(GL_LIGHTING);
    glClear(GL_DEPTH_BUFFER_BIT);
    glstate_->pick_init (false);

    // do the picking
    SceneGraph::PickAction action(*glstate_, _pickTarget, curDrawMode_);
    SceneGraph::traverse(sceneGraphRoot_, action);
    int hits = glRenderMode(GL_RENDER);

    // restore GL state
    glMatrixMode( GL_PROJECTION );
    glLoadMatrixd(projection.get_raw_data());
    glMatrixMode( GL_MODELVIEW );
    glLoadMatrixd(modelview.get_raw_data());
    ACG::GLState::enable(GL_LIGHTING);


    // process hit record
    if ( hits > 0 )
    {
      GLuint *ptr = &selectionBuffer[0],
      z,
      min_z=~(0u),
      max_z=0;

      for (int i=0; i<hits; ++i)
      {
        const GLuint num_names = *ptr++;
        if ( num_names != NAME_STACK_SIZE )
        {
          std::cerr << "QtBaseViewer::pick() : namestack error\n\n";
          return false;
        }

        if ( (z = *ptr++) < min_z )
        {
          min_z = z;
          max_z = *ptr++;
          for (unsigned int j=0; j<num_names; ++j)
            nameBuffer[j] = *ptr++;
        }
        else ptr += 1+num_names;
      }

      _nodeIdx   = nameBuffer[0];
      _targetIdx = nameBuffer[1];

      if (_hitPointPtr)
      {
        GLuint zscale=~(0u);
        GLdouble min_zz = ((GLdouble)min_z) / ((GLdouble)zscale);
        GLdouble max_zz = ((GLdouble)max_z) / ((GLdouble)zscale);
        GLdouble zz     = 0.5F * (min_zz + max_zz);
        *_hitPointPtr = glstate_->unproject(Vec3d(x,y,zz));
      }

      return true;
    }
    else if (hits < 0)
      std::cerr << "QtBaseViewer::pick() : selection buffer overflow\n\n";
  }

  return false;
}


//-----------------------------------------------------------------------------


bool
QtBaseViewer::
fast_pick( const QPoint&  _mousePos,
      Vec3d&         _hitPoint )
{
  // get x,y,z values of pixel
  GLint     x(_mousePos.x()), y(glHeight() - _mousePos.y());
  GLfloat   z;


  makeCurrent();
  glPixelStorei(GL_PACK_ALIGNMENT, 1);
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glReadPixels(x, y, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &z);


  if (z < 0.99999)
  {
    _hitPoint = glstate_->unproject( Vec3d(x, y, z) );
    return true;
  }
  else return false;
}

//-----------------------------------------------------------------------------


void QtBaseViewer::pickMode( int _id )
{
  if (_id < (int) pick_modes_.size() )
  {
    pick_mode_idx_  = _id;
    pick_mode_name_ = pick_modes_[pick_mode_idx_].name;

    // adjust mouse tracking
    if ( actionMode_ == PickingMode )
      trackMouse(pick_modes_[pick_mode_idx_].tracking);

    // adjust Cursor
    if ( actionMode_ == PickingMode )
      glView_->setCursor(pick_modes_[pick_mode_idx_].cursor);

    // emit signal
    emit(signalPickModeChanged(pick_mode_name_));
  }
}


//-----------------------------------------------------------------------------


void QtBaseViewer::addPickMode(const std::string& _name,
                               bool _tracking,
                               int  _pos,
                               bool _visible,
                               QCursor _cursor)
{
  if ((unsigned int)_pos < pick_modes_.size())
  {
    std::vector<PickMode>::iterator it = pick_modes_.begin();
    it += _pos+1;
    pick_modes_.insert(it, PickMode(_name, _tracking, _visible, _cursor));
  }
  else
    pick_modes_.push_back(PickMode(_name, _tracking, _visible, _cursor));

  updatePickMenu();
}

//-----------------------------------------------------------------------------

void QtBaseViewer::setPickModeCursor(const std::string& _name, QCursor _cursor)
{
  for (uint i=0; i < pick_modes_.size(); i++)
    if ( pick_modes_[i].name == _name ){
      pick_modes_[i].cursor = _cursor;

      //switch cursor if pickMode is active
      if (pick_mode_name_ == _name && actionMode_ == PickingMode)
        glView_->setCursor(_cursor);
      break;
    }
}

//-----------------------------------------------------------------------------

void QtBaseViewer::setPickModeMouseTracking(const std::string& _name, bool _mouseTracking)
{
  for (uint i=0; i < pick_modes_.size(); i++)
    if ( pick_modes_[i].name == _name ){
      pick_modes_[i].tracking = _mouseTracking;

      //switch cursor if pickMode is active
      if (pick_mode_name_ == _name && actionMode_ == PickingMode)
        trackMouse(_mouseTracking);
      break;
    }
}

//-----------------------------------------------------------------------------


void QtBaseViewer::clearPickModes()
{
  pick_modes_.clear();
  pick_mode_idx_  = -1;
  pick_mode_name_ = "";
  updatePickMenu();
}


//-----------------------------------------------------------------------------


const std::string& QtBaseViewer::pickMode() const
{
  return pick_mode_name_;
}


//-----------------------------------------------------------------------------


void QtBaseViewer::pickMode(const std::string& _name)
{
  for (unsigned int i=0; i<pick_modes_.size(); ++i)
  {
    if (pick_modes_[i].name == _name)
    {
      pickMode( i );
      updatePickMenu();
      return;
    }
  }
}

//-----------------------------------------------------------------------------

void QtBaseViewer::pickingMode() {
  actionMode(PickingMode);
}


//=============================================================================
} // namespace QtWidgets
} // namespace ACG
//=============================================================================