source: GTP/trunk/Lib/Vis/Preprocessing/src/Beam.cpp @ 2176

#include "VssRay.h"
#include "Beam.h"
#include "Mesh.h"
#include "Polygon3.h"

namespace GtpVisibilityPreprocessor {

void
Beam::Construct(const AxisAlignedBox3 &box, const AxisAlignedBox3 &dBox)
{
  // the frustum is defined by set of negative halfspace described by mPlanes
  
  // construct
  Vector3 center = box.Center();
  Vector3 dCenter = dBox.Center();

  // "back plane"
  mPlanes.push_back(Plane3(-VssRay::GetDirection(dCenter.x, dCenter.y), center));
  
  Vector3 directions[4];
  directions[0] = VssRay::GetDirection(dBox.Min().x, dBox.Min().y);
  directions[1] = VssRay::GetDirection(dBox.Max().x, dBox.Min().y);
  directions[2] = VssRay::GetDirection(dBox.Max().x, dBox.Max().y);
  directions[3] = VssRay::GetDirection(dBox.Min().x, dBox.Max().y);
  
  // side planes
  mPlanes.push_back(Plane3(-CrossProd(directions[0], directions[1]), center));
  mPlanes.push_back(Plane3(-CrossProd(directions[1], directions[2]), center));
  mPlanes.push_back(Plane3(-CrossProd(directions[2], directions[3]), center));
  mPlanes.push_back(Plane3(-CrossProd(directions[3], directions[0]), center));

  // now make sure all planes contain the spatial box
  int i, j;
  for (i=0; i < mPlanes.size(); i++) 
  {
          float maxDist = 0;
          
          for (j=0; j < 8; j++) 
          {
                float dist = mPlanes[i].Distance(box.GetVertex(j));
        
                if (dist > maxDist)
                        maxDist = dist;
          }

          mPlanes[i].mD -= maxDist;
  }

  mBox = box;
  mDirBox = dBox;
  
  SetValid();
}

// conservative frustum box intersection
// returns
// 0 - box intersects the frustum
// -1 - box intersects the frustum and is fully inside
// 1 - box does not intersect the frustum

int
Beam::ComputeIntersection(const AxisAlignedBox3 &box)
{
  int i;
  int result = -1;
  for (i=0; i < mPlanes.size(); i++) {
        int side = box.Side(mPlanes[i]);
        if (side == 1)
          return 1;
        if (side > result)
          result = side;
  }
  return result;
}


Beam::~Beam()
{
        DEL_PTR(mMesh);
}


void Beam::ComputePerspectiveFrustum(float &left, float &right,
                                                                         float &bottom, float &top,
                                                                         float &near, float &far,
                                                                         const AxisAlignedBox3 &sceneBBox) const
{
        const float xDirRange = mDirBox.Max().x - mDirBox.Min().x;
        const float yDirRange = mDirBox.Max().y - mDirBox.Min().y;
        //Debug << "xdir range: " << xDirRange << endl;
        //Debug << "ydir range: " << yDirRange << endl;

        near = 0.1f; // NOTE: what is the best value for near and far plane?
        far = 2.0f * Magnitude(sceneBBox.Diagonal());
        
        right = fabs(near * tan(xDirRange * 0.5f));
        left = -right;

        top = fabs(near * tan(yDirRange * 0.5f));
        bottom = -top;
}


void Beam::ComputeOrthoFrustum(float &left, float &right,
                                                           float &bottom, float &top,
                                                           float &near, float &far,
                                                           const AxisAlignedBox3 &sceneBBox) const
{
        const int vAxis = GetMainDirection().DrivingAxis();
        const int axis2 = (vAxis + 1) % 3;
        const int axis3 = (vAxis + 2) % 3;

        const float xDirRange = mBox.Max()[axis2] - mDirBox.Min()[axis2];
        const float yDirRange = mDirBox.Max()[axis3] - mDirBox.Min()[axis3];

        near = 0.1f; // NOTE: what is the best value for near and far plane?
        far = 2.0f * Magnitude(sceneBBox.Diagonal());

        right = xDirRange * 0.5f;
        left = -right;

        top = yDirRange * 0.5f;
        bottom = -top;
}


Vector3 Beam::GetMainDirection() const
{
        return - mPlanes[0].mNormal;
}


void BeamSampleStatistics::Print(std::ostream &app) const
{
  app << "===== Beam sample statistics ===============\n";

  app << "#N_PVSSIZE ( size of pvs )\n" << pvsSize << "\n";

  app << "#N_RAYS ( Number of rays )\n" << rays << "\n";

  app << "#N_RAYCONTRIBUTIONS ( number of ray constributions )\n" <<
    rayContributions << "\n";

  app << "#N_RAYLENGHTENTROPY  ( Ray lenght entropy )\n" <<
    rayLengthEntropy << "\n";

  app << "#N_IMPORTANCE  ( importance )\n" <<
    importance << "\n";

  app << "#N_CTIME  ( Construction time [s] )\n"
      << Time() << " \n";

  app << "===== END OF KdTree statistics ==========\n";

}


void Beam::CreateMesh(const float zfar)
{
        if (mMesh)
                return;

        mMesh = new Mesh();
        
        // -- compute far plane

        // box should not never remove part of beam polygons
        Vector3 bmin = mBox.Min() - Vector3(zfar * 2.0f);
        Vector3 bmax = mBox.Max() + Vector3(zfar * 2.0f);

        AxisAlignedBox3 bbox(bmin, bmax);
        Plane3 fplane;
        fplane.mNormal = -mPlanes[0].mNormal;

        // NOTE: beam far plane must not not be culled by gl far plane
        fplane.mD = mPlanes[0].mD - zfar - 1.0f; 
        mPlanes.push_back(fplane);

        for (int i = 0; i < mPlanes.size(); ++ i)
        {
                Polygon3 *poly = bbox.CrossSection(mPlanes[i]);
                
                if (!poly->Valid(Limits::Small))
                        DEL_PTR(poly);
                
                for (int j = 0; (j < mPlanes.size()) && poly; ++ j)
                {
                        if (j != i)
                        {
                                Polygon3 *front = new Polygon3();
                                Polygon3 *back = new Polygon3();
                                
                                poly->Split(mPlanes[j], *front, *back, Limits::Small);
                                DEL_PTR(poly);
                                DEL_PTR(front);

                                if (!back->Valid(Limits::Small))
                                        DEL_PTR(back);
                                poly = back;
                        }
                }
        
                if (poly)
                {
                        IncludePolyInMesh(*poly, *mMesh);
                }
        }

        // remove far plane
        mPlanes.pop_back();
}

}