/// <summary>
/// Initialize all squares in the mazeExtension (everything but trajectoryDistance).
/// </summary>
/// <param name="maze"></param>
private void InitializeMazeExtension(Maze maze)
{
for (int i = 0; i < maze.XSize; i++)
{
for (int j = 0; j < maze.YSize; j++)
{
MazeSquare sq = maze[i, j];
MazeSquareExtension sqe = mazeExtension[i, j];
// extendedSquare:
sqe.extendedSquare = sq;
if (sq.isReserved)
{
// isDeadEnd:
sqe.isDeadEnd = true;
sqe.trajectoryDistance = -1;
}
else
{
// neighbors:
sqe.neighbors = new List <MazeSquareExtension>(4);
for (WallPosition wp = WallPosition.WP_MIN; wp <= WallPosition.WP_MAX; wp++)
{
MazeSquare sq2 = sq.NeighborSquare(wp);
if (sq2 != null && !sq2.isReserved)
{
sqe.neighbors.Add(mazeExtension[sq2.XPos, sq2.YPos]);
}
}
// Negative values mean: not initialized
sqe.trajectoryDistance = int.MinValue;
}
}
}
}
/// <summary>
/// Returns the center square of the given sqaure's partition.
/// </summary>
/// <param name="sq"></param>
/// <returns></returns>
private MazeSquare ReferenceSquare(MazeSquare sq)
{
// x and y index of the current square's partition
int px = sq.XPos * xPartitions / xSize, py = sq.YPos * yPartitions / ySize;
// x and y coordinates of the selected partition's center square
int xCenter = (2 * px + 1) * xSize / (2 * xPartitions);
int yCenter = (2 * py + 1) * ySize / (2 * yPartitions);
// Apply this partition's offset.
if (xOffCenter != null && yOffCenter != null)
{
xCenter += xOffCenter[px, py];
yCenter += yOffCenter[px, py];
}
// If defined: Find the vertex closest to the given square.
if (vertices != null)
{
MazeSquare closestVertex = vertices[0];
double closestDistance = Maze.Distance(sq, closestVertex);
for (int i = 1; i < vertices.Length; i++)
{
double d = Maze.Distance(sq, vertices[i]);
if (d < closestDistance)
{
closestVertex = vertices[i];
closestDistance = d;
}
}
xCenter = closestVertex.XPos;
yCenter = closestVertex.YPos;
}
return(new MazeSquare(xCenter, yCenter));
}
/// <summary>
/// Setup method: Define the adjoining sqare on the other side of a wall.
/// </summary>
/// <param name="side"></param>
/// <param name="neighbor"></param>
internal void SetNeighbor(WallPosition side, MazeSquare neighbor)
{
this.neighbors[(int)side] = neighbor;
}
public override bool[] PreferredDirections(MazeSquare sq)
{
// A measure of how many template squares' wall are already open.
// When positive, this square's wall should also be open.
double[] openTemplates = new double[4];
for (int x = sq.XPos % gridWidth; x < maze.XSize; x += gridWidth)
{
for (int y = sq.YPos % gridHeight; x < maze.YSize; x += gridHeight)
{
#region Skip the square that is being evaluated.
if (x == sq.XPos && y == sq.YPos)
{
continue;
}
#endregion
for (WallPosition p = WallPosition.WP_MIN; p <= WallPosition.WP_MAX; p++)
{
#region Skip this wall if it is the maze border or a reserved area border.
bool skip = false;
switch (p)
{
case WallPosition.WP_W:
skip = (x == 0 || maze[x - 1, y].isReserved);
break;
case WallPosition.WP_E:
skip = (x + 1 == maze.XSize || maze[x + 1, y].isReserved);
break;
case WallPosition.WP_N:
skip = (y == 0 || maze[x, y - 1].isReserved);
break;
case WallPosition.WP_S:
skip = (y + 1 == maze.YSize || maze[x, y + 1].isReserved);
break;
}
if (skip)
{
continue;
}
#endregion
double dx = x - sq.XPos, dy = y - sq.YPos, d = Math.Sqrt(dx * dx + dy * dy);
double increment = 0;
// Let the influence of farther regions decrease rather slowly.
d = Math.Log(d, Math.E);
switch (maze[x, y][p])
{
case WallState.WS_OPEN:
increment = +1.0 / d;
break;
case WallState.WS_CLOSED:
case WallState.WS_OUTLINE:
increment = -1.0 / d;
break;
default:
case WallState.WS_MAYBE:
increment = +0.1 / d;
break;
}
openTemplates[(int)p] += increment;
}
}
}
bool[] result = new bool[4];
for (int p = 0; p < 4; p++)
{
result[p] = (openTemplates[p] >= 0);
}
return(result);
}
/// <summary> /// Returns an array four boolean values, indexed by the WallPosition constants. /// The value is true when that wall is a preferred direction for paths from the given square. /// </summary> /// <param name="sq"></param> /// <returns></returns> public abstract bool[] PreferredDirections(MazeSquare sq);
public override bool[] PreferredDirections(MazeSquare sq)
{
bool[] result = new bool[4] {
false, false, false, false
};
#region Collect the distances of all neighbor squares (including diagonals) from the reference square.
// Actually, this is the (absolute) difference between the distances of a neighbor square and sq itself.
double[,] distances = new double[3, 3];
// The distance of the current square to the reference square should be approximated.
MazeSquare sq0 = this.ReferenceSquare(sq);
double d0 = Maze.Distance(sq, sq0);
// Rounding to the next integer will approximate circles in 1 unit steps.
if (approximateCircles)
{
d0 = Math.Round(d0);
}
for (int i = -1; i <= +1; i++)
{
for (int j = -1; j <= +1; j++)
{
// Note: this[x,y] is not defined outside the maze size.
MazeSquare sq1 = new MazeSquare(sq.XPos + i, sq.YPos + j);
distances[i + 1, j + 1] = (minimizeDistance ? +1 : -1) * Math.Abs(Maze.Distance(sq1, sq0) - d0);
}
}
#endregion
#region Find a range of distances including the current square and two of the neighbors.
double d1 = double.MaxValue, d2 = double.MaxValue;
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
if (i == 1 && j == 1) // Discard the current square.
{
continue;
}
if (distances[i, j] >= d2) // Discard distances greater than the current second best.
{
continue;
}
if (distances[i, j] >= d1) // This is a new second best distance.
{
d2 = distances[i, j];
}
else // This is a new best distance.
{
d2 = d1;
d1 = distances[i, j];
}
}
}
#endregion
#region Add the directions to the two best neighbors to the result.
if (distances[1, 0] <= d2) // straight north
{
result[(int)WallPosition.WP_N] = true;
}
if (distances[0, 1] <= d2) // straight west
{
result[(int)WallPosition.WP_W] = true;
}
if (distances[1, 2] <= d2) // straight south
{
result[(int)WallPosition.WP_S] = true;
}
if (distances[2, 1] <= d2) // straight east
{
result[(int)WallPosition.WP_E] = true;
}
// For approximating a diagonal connection, we follow the closer path (unless this logic is inverted).
if (distances[0, 0] <= d2) // north-west
{
result[(int)((distances[1, 0] < distances[0, 1] == followDiagonals) ? WallPosition.WP_N : WallPosition.WP_W)] = true;
}
if (distances[2, 0] <= d2) // north-east
{
result[(int)((distances[1, 0] < distances[2, 1] == followDiagonals) ? WallPosition.WP_N : WallPosition.WP_E)] = true;
}
if (distances[0, 2] <= d2) // south-west
{
result[(int)((distances[1, 2] < distances[0, 1] == followDiagonals) ? WallPosition.WP_S : WallPosition.WP_W)] = true;
}
if (distances[2, 2] <= d2) // south-east
{
result[(int)((distances[1, 2] < distances[2, 1] == followDiagonals) ? WallPosition.WP_S : WallPosition.WP_E)] = true;
}
#endregion
return(result);
}
/// <summary>
/// Registers the given square as visited.
/// </summary>
/// <param name="sq"></param>
/// <returns>a list of dead end squares</returns>
public List <MazeSquare> Visit(MazeSquare sq)
{
List <MazeSquare> result = new List <MazeSquare>();
MazeSquareExtension sqe = mazeExtension[sq.XPos, sq.YPos];
// Don't process squares that have been visited before.
if (sqe.isDeadEnd)
{
return(result);
}
// The visited square is marked as dead.
sqe.isDeadEnd = true;
int d = sqe.trajectoryDistance;
if (d > 0)
{
sqe.trajectoryDistance *= -1;
}
else
{
d *= -1;
}
if (d == 0)
{
// This is the end square. No need to kill any more squares...
return(result);
}
// Add neighbors to the list of uncertainSquares if their trajectory passed through the visited square.
// That is the case if their distance is greater by one than the visited square's distance.
for (int i = 0; i < sqe.neighbors.Count; i++)
{
MazeSquareExtension sqe2 = sqe.neighbors[i];
if (sqe2.trajectoryDistance == d + 1)
{
AddUncertainSquare(sqe2, -1);
}
}
if (HarmlessConstellation(sqe))
{
return(result);
}
// Add all squares whose trajectory depends on the ones already inserted.
CollectUncertainSquares();
// The areas next to all confirmedSquares will receive an adjusted trajectoryDistance.
ReviveConfirmedSquaresNeighbors();
// The remaining uncertainSquares with negative (invalid) trajectoryDistance are dead.
for (int j = 0; j < uncertainSquares.Count; j++)
{
MazeSquareExtension sqe2 = uncertainSquares[j];
if (sqe2.trajectoryDistance < 0 && !sqe2.isDeadEnd)
{
sqe2.isDeadEnd = true;
if (sqe2.extendedSquare.MazeId == sq.MazeId)
{
result.Add(sqe2.extendedSquare);
}
}
}
// Empty the internal lists.
uncertainSquares.Clear();
confirmedSquares.Clear();
return(result);
}
/// <summary>
/// Returns true if the given square is marked as dead.
/// A square is dead if
/// a) it is a reserved area in the maze
/// b) it has already been visited
/// c) there is no trajectory leading to the maze's end square
/// </summary>
/// <param name="sq"></param>
/// <returns></returns>
public bool IsDead(MazeSquare sq)
{
return(mazeExtension[sq.XPos, sq.YPos].isDeadEnd);
}
/// <summary>
/// Convert all undecided walls to either closed or open.
/// In the resulting maze, there must be a path from every square to every other square.
/// There must not be any circles, i.e. the maze must have a tree-like structure.
/// </summary>
private void BuildMaze()
{
// We hold a number of active squares in a stack.
// Make the initial capacity sufficient to hold all squares.
//
Stack <MazeSquare> stack = new Stack <MazeSquare>(xSize * ySize);
List <MazeSquare> outlineSquares = new List <MazeSquare>();
List <WallPosition> outlineWalls = new List <WallPosition>();
#region Start with a single random cell in the stack.
while (true)
{
int x = random.Next(xSize);
int y = random.Next(ySize);
MazeSquare sq = this[x, y];
if (sq.MazeId == this.MazeId)
{
sq.isConnected = true;
stack.Push(sq);
break;
}
}
#endregion
#region Extend the maze by visiting the cells next to those in the stack.
while (stack.Count > 0)
{
List <WallPosition> unresolvedWalls = new List <WallPosition>((int)WallPosition.WP_NUM);
MazeSquare sq0 = stack.Pop();
// Collect the unfixed walls of sq0.
//
for (WallPosition wp = WallPosition.WP_MIN; wp <= WallPosition.WP_MAX; wp++)
{
switch (sq0[wp])
{
case WallState.WS_MAYBE:
MazeSquare sq = sq0.NeighborSquare(wp);
if (sq.isConnected || sq.MazeId != sq0.MazeId)
{
sq0[wp] = sq[MazeSquare.OppositeWall(wp)] = WallState.WS_CLOSED;
}
else
{
unresolvedWalls.Add(wp);
}
break; // WS_MAYBE
case WallState.WS_OUTLINE:
outlineSquares.Add(sq0);
outlineWalls.Add(wp);
break; // WS_OUTLINE
}
} // foreach wp
// Discard this square if it has no unresolved walls.
if (unresolvedWalls.Count == 0)
{
// Note: This is the only place that may end the loop.
// If the stack is empty: Open one outline wall.
if (stack.Count == 0)
{
while (outlineSquares.Count > 0)
{
// Select a random square with an outline wall.
int p = random.Next(outlineSquares.Count);
MazeSquare sq = outlineSquares[p];
WallPosition wp = outlineWalls[p];
outlineSquares.RemoveAt(p);
outlineWalls.RemoveAt(p);
if (sq[wp] == WallState.WS_OUTLINE)
{
sq[wp] = WallState.WS_MAYBE;
stack.Push(sq);
// This square will be used in the next iteration.
break; // from while(outlineSquares)
}
}
}
continue; // no walls to choose from
}
// Add the current cell to the stack.
// Note: Do this before replacing unresolvedWalls with preferredWalls.
if (unresolvedWalls.Count > 1)
{
stack.Push(sq0);
}
// Use only preferred wall positions.
if (unresolvedWalls.Count > 1 && irregularMazeShape != null &&
(random.Next(100) < irregularMazeShape.ApplicationPercentage(this.irregularity)))
{
bool[] preferredPositions = irregularMazeShape.PreferredDirections(sq0);
List <WallPosition> preferredWalls = new List <WallPosition>(unresolvedWalls.Count);
foreach (WallPosition p in unresolvedWalls)
{
if (preferredPositions[(int)p])
{
preferredWalls.Add(p);
}
}
if (preferredWalls.Count > 0)
{
unresolvedWalls = preferredWalls;
}
}
// Choose one wall.
WallPosition wp0 = unresolvedWalls[random.Next(unresolvedWalls.Count)];
MazeSquare sq1 = sq0.NeighborSquare(wp0);
// Open the wall.
sq0[wp0] = sq1[MazeSquare.OppositeWall(wp0)] = WallState.WS_OPEN;
// Add the new cell to the stack.
sq1.isConnected = true;
stack.Push(sq1);
} // while stack is not empty
#endregion
}
/// <summary>
/// Returns the square diametrically opposed to the given square.
/// </summary>
public MazeSquare GetOpposedSquare(MazeSquare sq)
{
Rectangle bbox = this.GetBoundingBox();
return(this[bbox.Right - 1 - sq.XPos, bbox.Bottom - 1 - sq.YPos]);
}