ClippingNode.cc

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/*===========================================================================*\
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 *   $Revision$                                                       *
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\*===========================================================================*/




//=============================================================================
//
//  CLASS ClippingNode - IMPLEMENTATION
//
//=============================================================================


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


#include "ClippingNode.hh"

#include <QImage>


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


namespace ACG {
namespace SceneGraph {

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


void
ClippingNode::set_plane(const Vec3f& _position, 
                        const Vec3f& _normal, 
                        float _eps)
{
  position_    = _position;
  normal_      = _normal; normal_.normalize();
  slice_width_ = _eps;
  

  // one clipping plane
  if (slice_width_ == 0.0)
  {
    plane0_[0] = normal_[0];
    plane0_[1] = normal_[1];
    plane0_[2] = normal_[2];
    plane0_[3] = -(normal_|position_);
  }


  // two planes -> slice
  else 
  {
    float d = -(normal_|position_);
    if (d > 0) { normal_ = -normal_; d = -d; }
    
    plane0_[0] = normal_[0];
    plane0_[1] = normal_[1];
    plane0_[2] = normal_[2];
    plane0_[3] = d + 0.5f*slice_width_;

    plane1_[0] = -normal_[0];
    plane1_[1] = -normal_[1];
    plane1_[2] = -normal_[2];
    plane1_[3] = -(d - 0.5f*slice_width_);
  }


  set_offset(offset_);
}


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


void 
ClippingNode::set_offset(float _offset)
{
  offset_ = _offset;

  offset_plane0_[0] = plane0_[0];
  offset_plane0_[1] = plane0_[1];
  offset_plane0_[2] = plane0_[2];
  offset_plane0_[3] = plane0_[3] - offset_;

  offset_plane1_[0] = plane1_[0];
  offset_plane1_[1] = plane1_[1];
  offset_plane1_[2] = plane1_[2];
  offset_plane1_[3] = plane1_[3] + offset_;
}


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

void ClippingNode::enter(GLState& /* _state */ , const DrawModes::DrawMode& /* _drawmode */ ) 
{
  // one clipping plane
  if (slice_width_ == 0.0)
  {
    glClipPlane(GL_CLIP_PLANE0, offset_plane0_);
    ACG::GLState::enable(GL_CLIP_PLANE0);
  }


  // two planes -> slice
  else 
  {
    glClipPlane(GL_CLIP_PLANE0, offset_plane0_);
    ACG::GLState::enable(GL_CLIP_PLANE0);
    glClipPlane(GL_CLIP_PLANE1, offset_plane1_);
    ACG::GLState::enable(GL_CLIP_PLANE1);
  }
}


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


void ClippingNode::leave(GLState& /* _state */ , const DrawModes::DrawMode& /* _drawmode */ )
{
  ACG::GLState::disable(GL_CLIP_PLANE0);
  if (slice_width_ > 0.0)
    ACG::GLState::disable(GL_CLIP_PLANE1);
}


//=============================================================================
} // namespace SceneGraph
} // namespace ACG
//=============================================================================