/home/master/UCL/VisualizationLibrary/src/vlGraphics/Billboard.cpp

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/*  Visualization Library                                                             */
/*  http://visualizationlibrary.org                                                   */
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/*  Copyright (c) 2005-2010, Michele Bosi                                             */
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#include <vlGraphics/Billboard.hpp>
#include <vlGraphics/Camera.hpp>

using namespace vl;

//-----------------------------------------------------------------------------
Billboard::Billboard()
{
  setAxis(vec3(0,1,0));
  setNormal(vec3(0,0,1));
  mType = BT_SphericalBillboard;
  VL_DEBUG_SET_OBJECT_NAME()
}
//-----------------------------------------------------------------------------
vec3 Billboard::position()
{
  return localMatrix().getT();
}
//-----------------------------------------------------------------------------
void Billboard::setPosition(const vec3& pos)
{
  setLocalMatrix( mat4::getTranslation(pos) );
}
//-----------------------------------------------------------------------------
void Billboard::computeWorldMatrix(Camera* camera)
{
  if( assumeIdentityWorldMatrix() )
  {
    setWorldMatrix( mat4() ); 
  }
  else
  if ( !camera )
  {
    Transform::computeWorldMatrix(NULL);
  }
  else
  {
    mat4 world_mat;
    vec3 pos = position();
    if (parent() && !parent()->assumeIdentityWorldMatrix())
      pos = parent()->worldMatrix() * pos;
    if ( type() == BT_SphericalBillboard )
    {
      // eye positional
      world_mat.setZ( (camera->modelingMatrix().getT() - pos).normalize() );
      world_mat.setY( camera->modelingMatrix().getY() );
      world_mat.setX( cross(world_mat.getY(), world_mat.getZ()) );
      world_mat = vl::mat4::getTranslation(pos) * world_mat;

      // eye directional
      //world_mat.setZ( camera->modelingMatrix().getZ() );
      //world_mat.setY( camera->modelingMatrix().getY() );
      //world_mat.setX( camera->modelingMatrix().getX() );
      //world_mat = vl::mat4::getTranslation(pos) * world_mat;
    }
    else
    if ( type() == BT_AxisAlignedBillboard )
    {
      vec3 normal = mNormal;
      vec3 bill_to_eye = (camera->modelingMatrix().getT() - pos).normalize();
      // flatten on the plane defined by the axis()
      normal      = normal      - axis() * dot(normal,      axis());
      bill_to_eye = bill_to_eye - axis() * dot(bill_to_eye, axis());
      normal.normalize();
      bill_to_eye.normalize();
      world_mat = vl::mat4::getTranslation(pos) * mat4::getRotation(normal,bill_to_eye);
    }

    setWorldMatrix( world_mat ); 
  }
}
//-----------------------------------------------------------------------------