private void FollowPath(double elapsed)
{
// Move to the next node in our path if we are close enough to
// our current target node.
if ((Position - _pathEnum.Current.Position).Length < NavigationDistance)
{
// Set path to null if we have reached our destination.
if (!_pathEnum.MoveNext())
{
_path = null;
}
}
if (_path != null)
{
_seekAtSteering.Location = _pathEnum.Current.Position;
Vector2 steeringForce = _seekAtSteering.Steer(this, elapsed) * 10;
Vector2 acceleration = steeringForce / Mass;
Velocity += acceleration * elapsed;
Velocity = Velocity.Truncate(MaxSpeed);
Position += Velocity * elapsed;
}
}
private void CreatePath()
{
// Calculate shortest path from current position to
// the current mouse position and store the IEnumerator
// of that path for future navigation.
GraphNode nearestCurrent =
_world.Graph.NearestNode(Position);
GraphNode nearestDestination =
_world.Graph.NearestNode(Mouse.Position);
try
{
_path = new AStarAlgorithm(_world.Graph)
.GetShortestPath(nearestCurrent, nearestDestination);
_pathEnum = _path.Path.GetEnumerator();
if (!_pathEnum.MoveNext())
{
// Delete path if we're already at the destination.
_path = null;
}
}
catch (ArgumentException)
{
Debug.WriteLine("Cannot plan a path to this location");
}
}