Example #1
0
bool ON_Arc::Create( // arc through 3 3d points
  const ON_3dPoint& P, // point P
  const ON_3dPoint& Q, // point Q
  const ON_3dPoint& R  // point R
  )
{
  ON_Circle c;
  double a = 0.0;

  for (;;)
  {

    if ( !c.Create(P,Q,R) )
      break;

    if ( !c.ClosestPointTo( R, &a ) )
      break;

    if ( !(a > 0.0) )
      break;
    
    if ( !Create( c, ON_Interval(0.0,a) ) )
      break;

    return true;
  }

  plane = ON_Plane::World_xy;
  radius = 0.0;
  m_angle.Set(0.0,0.0);

  return false;
}
Example #2
0
int ON_Intersect( const ON_Sphere& sphere0, 
                  const ON_Sphere& sphere1, 
                  ON_Circle& circle
                 )

{
  double r0 = sphere0.Radius();
  double r1 = sphere1.Radius();
  ON_3dPoint C0 = sphere0.Center();
  ON_3dPoint C1 = sphere1.Center();
  ON_3dVector D = C1-C0;
  double d = D.Length();
  if (!D.Unitize()){
    if (fabs(r1-r0) > ON_ZERO_TOLERANCE)
      return 0;//Same center, different radii
    return 3;//Same sphere.
  }

  //Spheres are appart.
  if (d > r0 + r1)
    return 0;

  //Spheres tangent and appart
  if (d == r0+r1){
    ON_3dPoint P = C0 + r0*D;
    circle.Create(P, 0.0);
    return 1;
  }

  //Spheres tangent, one inside the other
  if (d == fabs(r0-r1)){
    ON_3dPoint P = (r0 > r1) ? C0 + r0*D : C0 - r0*D;
    circle.Create(P, 0.0);
    return 1;
  }

  //Spheres don't intersect, one inside the other.
  if (d < fabs(r0-r1))
    return 0;

  //Intersection is a circle
  double x = 0.5*(d*d + r0*r0 - r1*r1)/d;
  if (x >= r0){//Shouldn't happen
    ON_3dPoint P = C0 + r0*D;
    circle.Create(P, 0.0);
    return 1;
  }
  if (x <= -r0){//Shouldn't happen
    ON_3dPoint P = C0 - r0*D;
    circle.Create(P, 0.0);
    return 1;
  }
  double y = r0*r0 - x*x;
  if (y < 0.0)//Shouldn't happen
    return 0;
  y = sqrt(y);

  ON_3dPoint P = C0 + x*D;
  ON_Plane plane(P, D);
  circle.Create(plane, y);
  return 2;
}