Method SimpleIntegrate

Filters/Generic/vtkGenericStreamTracer.cxx:1184–1245

------------------------------------------------------------------------------ This is used by sub-classes in certain situations. It does a lot less (for example, does not compute attributes) than Integrate.

// does a lot less (for example, does not compute attributes)
// than Integrate.
void vtkGenericStreamTracer::SimpleIntegrate(
  double seed[3], double lastPoint[3], double delt, vtkGenericInterpolatedVelocityField* func)
{
  vtkIdType numSteps = 0;
  vtkIdType maxSteps = 20;
  double error = 0;
  double stepTaken;
  double point1[3], point2[3];
  double velocity[3];
  double speed;

  (void)seed; // Seed is not used

  memcpy(point1, lastPoint, 3 * sizeof(double));

  // Create a new integrator, the type is the same as Integrator
  vtkInitialValueProblemSolver* integrator = this->GetIntegrator()->NewInstance();
  integrator->SetFunctionSet(func);

  while (true)
  {

    if (numSteps++ > maxSteps)
    {
      break;
    }

    // Calculate the next step using the integrator provided
    // Break if the next point is out of bounds.
    if (integrator->ComputeNextStep(point1, point2, 0, delt, stepTaken, 0, 0, 0, error) != 0)
    {
      memcpy(lastPoint, point2, 3 * sizeof(double));
      break;
    }

    // This is the next starting point
    for (int i = 0; i < 3; i++)
    {
      point1[i] = point2[i];
    }

    // Interpolate the velocity at the next point
    if (!func->FunctionValues(point2, velocity))
    {
      memcpy(lastPoint, point2, 3 * sizeof(double));
      break;
    }

    speed = vtkMath::Norm(velocity);

    // Never call conversion methods if speed == 0
    if ((speed == 0) || (speed <= this->TerminalSpeed))
    {
      break;
    }

    memcpy(point1, point2, 3 * sizeof(double));
    // End Integration