private void Propagate(int x, int y, int z)
{
//Reset the map that keeps track of the changes.
ReInitMapOfChanges();
//Queue the first element.
var nodesToVisit = new Queue <Coord3D>();
nodesToVisit.Enqueue(new Coord3D(x, y, z));
//Perform a Breadth-First grid traversal.
while (nodesToVisit.Any())
{
var current = nodesToVisit.Dequeue();
mapOfChanges.SetValue(true, current.X, current.Y, current.Z);
//Get the list of the allowed neighbours of the current node
var nghbrsMaps = outputMatrix[current.X, current.Y, current.Z].Select(possibleElement => NeighboursMap[possibleElement]).ToList();
var allowedNghbrs = nghbrsMaps.SelectMany(dict => dict)
.ToLookup(pair => pair.Key, pair => pair.Value)
.ToDictionary(group => group.Key, group => group.SelectMany(list => list).ToList());
//For every possible direction check if the node has already been affected by the propagation.
//If it hasn't queue it up and mark it as visited, otherwise move on.
foreach (var direction in Directions)
{
var nodeToBeChanged = current.Add(direction.X, direction.Y, direction.Z);
if (outputMatrix.OutOfBounds(nodeToBeChanged) && !Periodic)
{
continue;
}
if (outputMatrix.OutOfBounds(nodeToBeChanged) && Periodic)
{
nodeToBeChanged = new Coord3D(Mod(nodeToBeChanged.X, outputMatrix.GetLength(0)),
Mod(nodeToBeChanged.Y, outputMatrix.GetLength(1)),
Mod(nodeToBeChanged.Z, outputMatrix.GetLength(2)));
if (mapOfChanges.OutOfBounds(nodeToBeChanged))
{
continue;
}
}
//Count the states before the propagation.
var statesBefore = outputMatrix[nodeToBeChanged.X, nodeToBeChanged.Y, nodeToBeChanged.Z].Count;
//Eliminate neighbours that are not allowed from the output matrix
var allowedNghbrsInDirection = allowedNghbrs[direction].Distinct().ToList();
outputMatrix[nodeToBeChanged.X, nodeToBeChanged.Y, nodeToBeChanged.Z]
.RemoveAll(neighbour => !allowedNghbrsInDirection.Contains(neighbour));
//Count the states after, if nbBefore != nbAfter queue it up.
var statesAfter = outputMatrix[nodeToBeChanged.X, nodeToBeChanged.Y, nodeToBeChanged.Z].Count;
//Check for contradictions
// TODO Add a backtrack recovery system to remedy the contradictions.
if (outputMatrix[nodeToBeChanged.X, nodeToBeChanged.Y, nodeToBeChanged.Z].Count == 0)
{
try {
ChosenPoints.Add(new Coord3D(x, y, z));
RollbackState();
TotalRollbacks++;
return;
}
catch (InvalidOperationException e) {
contradiction = true;
return;
}
}
//Queue it up in order to spread the info to its neighbours and mark it as visited.
if (statesBefore != statesAfter)
{
if (!nodesToVisit.Contains(nodeToBeChanged))
{
nodesToVisit.Enqueue(nodeToBeChanged);
}
}
}
}
ChosenPoints.Clear();
if (TotalRollbacks > TOTAL_ROLLBACKS_ALLOWED)
{
contradiction = true;
return;
}
generationFinished = CheckIfFinished();
}