public static void FindExplorePath2Opt(ExploreCell start_cell, List <ExploreCell> explore_cells, CellsDistancer distances, ref List <Vec3> path)
{
path.Clear();
if (start_cell == null)
{
return;
}
List <int> cells_id_in_start_cell_network = distances.GetConnectedTo(start_cell.GlobalId);
List <ExploreCell> best_tour = explore_cells.FindAll(c => cells_id_in_start_cell_network.Contains(c.GlobalId));
best_tour.RemoveAll(c => c.Explored || c.Neighbours.Count == 0);
if (start_cell.Explored)
{
best_tour.Insert(0, start_cell);
}
if (best_tour.Count == 1)
{
path.Add(best_tour[0].Position);
return;
}
float best_dist = GetTravelDistance(best_tour, distances);
if (best_tour.Count < 90)
{
// based on http://en.wikipedia.org/wiki/2-opt
while (true)
{
bool better_found = false;
for (int i = 1; i < best_tour.Count - 1; ++i)
{
for (int k = i + 1; k < best_tour.Count; ++k)
{
float new_dist = Swap2OptDistance(best_tour, distances, i, k);
if (new_dist < best_dist)
{
Swap2Opt(ref best_tour, i, k);
best_dist = new_dist;
better_found = true;
break;
}
}
if (better_found)
{
break;
}
}
if (!better_found)
{
break;
}
}
}
else // greedy
{
// based on http://on-demand.gputechconf.com/gtc/2014/presentations/S4534-high-speed-2-opt-tsp-solver.pdf
while (true)
{
float min_change = 0;
int min_i = -1;
int min_j = -1;
for (int i = 0; i < best_tour.Count - 2; ++i)
{
for (int j = i + 2; j < best_tour.Count - 1; ++j)
{
int city_a = best_tour[i].GlobalId;
int city_b = best_tour[i + 1].GlobalId;
int city_c = best_tour[j].GlobalId;
int city_d = best_tour[j + 1].GlobalId;
float change = (distances.GetDistance(city_a, city_c) + distances.GetDistance(city_b, city_d)) -
(distances.GetDistance(city_a, city_b) + distances.GetDistance(city_c, city_d));
if (change < min_change)
{
min_change = change;
min_i = i + 1;
min_j = j;
}
}
}
if (min_change >= 0)
{
break;
}
// apply min_i/min_j move
ExploreCell t = best_tour[min_i];
best_tour[min_i] = best_tour[min_j];
best_tour[min_j] = t;
}
}
//Navmesh.Log("[FindExplorePath 2-Opt] Final solution distance: " + GetTravelDistance(tour, distances));
foreach (ExploreCell cell in best_tour)
{
path.Add(cell.Position);
}
if (start_cell.Explored)
{
path.RemoveAt(0);
}
}
public static void FindExplorePath(ExploreCell start_cell, List <ExploreCell> explore_cells, CellsDistancer distances, ref List <Vec3> path)
{
//based on http://www.theprojectspot.com/tutorial-post/simulated-annealing-algorithm-for-beginners/6
path.Clear();
if (start_cell == null)
{
return;
}
List <int> cells_id_in_start_cell_network = distances.GetConnectedTo(start_cell.GlobalId);
List <ExploreCell> best_solution = explore_cells.FindAll(c => cells_id_in_start_cell_network.Contains(c.Id));
best_solution.RemoveAll(c => (c.Explored || c.Neighbours.Count == 0) && c.GlobalId != start_cell.GlobalId);
best_solution.Remove(start_cell);
best_solution.Insert(0, start_cell);
if (best_solution.Count == 1)
{
path.Add(best_solution[0].Position);
return;
}
float best_energy = GetTravelDistance(best_solution, distances);
List <ExploreCell> current_solution = best_solution;
float current_energy = best_energy;
Random rng = new Random();
double temp = 10000;
double alpha = 0.999;
double epsilon = 0.0001;
int temp_iterations = 2;
// Loop until system has cooled
while (temp > epsilon)
{
for (int iter = 0; iter < temp_iterations; ++iter)
{
// Create new neighbour tour
List <ExploreCell> new_solution = new List <ExploreCell>(current_solution);
// Get a random positions in the tour
int tour_pos_1 = rng.Next(1, new_solution.Count);
int tour_pos_2 = rng.Next(1, new_solution.Count);
// Swap them
ExploreCell t = new_solution[tour_pos_1];
new_solution[tour_pos_1] = new_solution[tour_pos_2];
new_solution[tour_pos_2] = t;
// Get energy of solutions
float new_energy = GetTravelDistance(new_solution, distances);
// Decide if we should accept the neighbour
if (AcceptanceProbability(current_energy, new_energy, temp) >= rng.NextDouble())
{
current_solution = new_solution;
current_energy = new_energy;
}
// Keep track of the best solution found
if (current_energy < best_energy)
{
best_solution = current_solution;
best_energy = current_energy;
}
}
// Cool system
temp *= alpha;
}
//Navmesh.Log("[FindExplorePath] Final solution distance: " + best_energy);
foreach (ExploreCell cell in best_solution)
{
path.Add(cell.Position);
}
if (start_cell.Explored)
{
path.RemoveAt(0);
}
}