C++ ON_Line::Direction方法代码示例

int ON_Intersect( // returns 0 = no intersections, 
                  // 1 = one intersection, 
                  // 2 = 2 intersections
                  // If 0 is returned, first point is point 
                  // on line closest to sphere and 2nd point is the point
                  // on the sphere closest to the line.
                  // If 1 is returned, first point is obtained by evaluating
                  // the line and the second point is obtained by evaluating
                  // the sphere.
                 const ON_Line& line, const ON_Sphere& sphere,
                  ON_3dPoint& A, ON_3dPoint& B // intersection point(s) returned here
                  )
{
  int rc = 0;
  const ON_3dPoint sphere_center = sphere.plane.origin;
  const double sphere_radius = fabs(sphere.radius);
  double tol = sphere_radius*ON_SQRT_EPSILON;
  if ( tol < ON_ZERO_TOLERANCE )
    tol = ON_ZERO_TOLERANCE;
  ON_3dPoint line_center = line.ClosestPointTo(sphere_center);
  double d = line_center.DistanceTo(sphere_center);
  if ( d >= sphere_radius-tol ) {
    rc = ( d <= sphere_radius-tol ) ? 1 : 0;
    A = line_center;
    B = sphere.ClosestPointTo(line_center);
  }
  else {
    d /= sphere_radius;
    double h = sphere_radius*sqrt(1.0 - d*d);
    ON_3dVector V = line.Direction();
    V.Unitize();
    A = sphere.ClosestPointTo(line_center - h*V);
    B = sphere.ClosestPointTo(line_center + h*V);
    d = A.DistanceTo(B);
    if ( d <= ON_ZERO_TOLERANCE ) {
      A = line_center;
      B = sphere.ClosestPointTo(line_center);
      rc = 1;
    }
    else
      rc = 2;
  }
  return rc;
}

bool ON_Line::IsFartherThan( double d, const ON_Line& L ) const
{
  ON_3dPoint A, B;
  double a, b, t, x;
  bool bCheckA, bCheckB;

  a = from.x; if (to.x < a) {b=a; a = to.x;} else b = to.x;
  if ( b+d < L.from.x && b+d < L.to.x )
    return true;
  if ( a-d > L.from.x && a-d > L.to.x )
    return true;

  a = from.y; if (to.y < a) {b=a; a = to.y;} else b = to.y;
  if ( b+d < L.from.y && b+d < L.to.y )
    return true;
  if ( a-d > L.from.y && a-d > L.to.y )
    return true;

  a = from.z; if (to.z < a) {b=a; a = to.z;} else b = to.z;
  if ( b+d < L.from.z && b+d < L.to.z )
    return true;
  if ( a-d > L.from.z && a-d > L.to.z )
    return true;

  if ( !ON_Intersect(*this,L,&a,&b) )
  {
    // lines are parallel or anti parallel
    if ( Direction()*L.Direction() >= 0.0 )
    {
      // lines are parallel
      a = 0.0;
      L.ClosestPointTo(from,&b);
      // If ( b >= 0.0), then this->from and L(b) are a pair of closest points.
      if ( b < 0.0 )
      {
        // Othersise L.from and this(a) are a pair of closest points.
        b = 0.0;
        ClosestPointTo(L.from,&a);
      }
    }
    else
    {
      // lines are anti parallel
      a = 1.0;
      L.ClosestPointTo(to,&b);
      // If ( b >= 0.0), then this->to and L(b) are a pair of closest points.
      if ( b < 0.0 )
      {
        // Othersise L.to and this(a) are a pair of closest points.
        b = 0.0;
        ClosestPointTo(L.from,&a);
      }
    }
  }

  A = PointAt(a);
  B = L.PointAt(b);
  x = A.DistanceTo(B);
  if (x > d)
    return true;

  bCheckA = true;
  if ( a < 0.0) a = 0.0; else if (a > 1.0) a = 1.0; else bCheckA=false;
  if (bCheckA )
  {
    A = PointAt(a);
    L.ClosestPointTo(A,&t);
    if (t<0.0) t = 0.0; else if (t > 1.0) t = 1.0;
    x = L.PointAt(t).DistanceTo(A);
  }

  bCheckB = true;
  if ( b < 0.0) b = 0.0; else if (b > 1.0) b = 1.0; else bCheckB=false;
  if ( bCheckB )
  {
    B = L.PointAt(b);
    ClosestPointTo(B,&t);
    if (t<0.0) t = 0.0; else if (t > 1.0) t = 1.0;
    t = PointAt(t).DistanceTo(B);
    if ( bCheckA )
    {
      if ( t<x ) x = t;
    }
    else
    {
      x = t;
    }
  }
 
  return (x > d);
}