#include "Ray.h"


// =========================================================
// Ray .. static item used for generation of unique ID for
// each instantiated ray

// it has to start from 1, since 0 is default and for the first
// ray initial value 0 will not work .. V.H.
// The value 0 is reserved for particular purpose - the rays
// that are converted to canonical space and thus the mailbox
// rayID identification does not work for them!
int
Ray::genID = 1;

// Precompute some Ray parameters. Most of them is used for
// ropes traversal.

void
Ray::Init()
{
  //  if (mType == LOCAL_RAY)
  //    intersections.reserve(1);
  //  else
  //    intersections.reserve(10);
  
  // apply the standard precomputation
  Precompute();
}

void
Ray::Precompute()
{
  // initialize inverted dir
  invDir.SetValue(0.0);
  
  SetID();
}

void
Ray::SetLoc(const Vector3 &l)
{
  loc = l;
}

// make such operation to slightly change the ray direction
// in case any component of ray direction is zero.
void
Ray::CorrectZeroComponents()
{
  const float eps = 1e-6;

  // it does change the ray direction very slightly,
  // but the size direction vector is not practically changed
  
  if (fabs(dir.x) < eps) {
    if (dir.x < 0.0)
      dir.x = -eps;
    else
      dir.x = eps;
  }
  
  if (fabs(dir.y) < eps) {
    if (dir.y < 0.0)
      dir.y = -eps;
    else
      dir.y = eps;
  }
  
  if (fabs(dir.z) < eps) {
    if (dir.z < 0.0)
      dir.z = -eps;
    else
      dir.z = eps;
  }
}


void
Ray::ComputeInvertedDir() const
{
  if ( (invDir.x != 0.0) ||
       (invDir.y != 0.0) ||
       (invDir.z != 0.0) )
    return; // has been already precomputed

  const float eps = 1e-6;
  const float invEps = 1e6;
  
  // it does change the ray direction very slightly,
  // but the size direction vector is not practically changed
  
  if (fabs(dir.x) < eps) {
    if (dir.x < 0.0)
      invDir.x = -invEps;
    else
      invDir.x = invEps;
  }
  else
    invDir.x = 1.0 / dir.x;
  
  if (fabs(dir.y) < eps) {
    if (dir.y < 0.0)
      invDir.y = -invEps;
    else
      invDir.y = invEps;
  }
  else
    invDir.y = 1.0 / dir.y;
  
  if (fabs(dir.z) < eps) {
    if (dir.z < 0.0)
      invDir.z = -invEps;
    else
      invDir.z = invEps;
  }
  else
    invDir.z = 1.0 / dir.z;

  return;
}