/// <summary>
/// Detects pyramid or hole (if any) at the given coordinates in the <see cref="Grid" />, and randomly switch
/// between pyramid and hole, based on <see cref="_probabilityP" /> and <see cref="_probabilityQ" /> parameters.
/// </summary>
/// <param name="p">
/// contains the coordinates where the function looks if there is a pyramid or hole in the <see cref="Grid" />.
/// </param>
private void RandomlySwitchFourCells(KpzNode[,] grid, KpzCoords p)
{
var neighbours = GetNeighbours(grid, p);
var currentPoint = grid[p.x, p.y];
bool changedGrid = false;
// We check our own {dx,dy} values, and the right neighbour's dx, and bottom neighbour's dx.
if (
// If we get the pattern {01, 01} we have a pyramid:
((currentPoint.dx && !neighbours.nx.dx) && (currentPoint.dy && !neighbours.ny.dy) &&
(_random.NextDouble() < _probabilityP)) ||
// If we get the pattern {10, 10} we have a hole:
((!currentPoint.dx && neighbours.nx.dx) && (!currentPoint.dy && neighbours.ny.dy) &&
(_random.NextDouble() < _probabilityQ))
)
{
// We make a hole into a pyramid, and a pyramid into a hole.
currentPoint.dx = !currentPoint.dx;
currentPoint.dy = !currentPoint.dy;
neighbours.nx.dx = !neighbours.nx.dx;
neighbours.ny.dy = !neighbours.ny.dy;
changedGrid = true;
}
if (_enableStateLogger)
{
StateLogger.AddKpzAction("RandomlySwitchFourCells", grid, p, neighbours, changedGrid);
}
}
/// <summary>
/// Runs an iteration of the KPZ algorithm (with <see cref="GridWidth"/> × <see cref="GridHeight"/> steps).
/// </summary>
public void DoIteration()
{
var numberOfStepsInIteration = GridWidth * GridHeight;
if (_enableStateLogger)
{
StateLogger.NewKpzIteration();
}
for (int i = 0; i < numberOfStepsInIteration; i++)
{
// We randomly choose a point on the grid.
// If there is a pyramid or hole, we randomly switch them.
var randomPoint = new KpzCoords {
x = _random.Next(0, GridWidth), y = _random.Next(0, GridHeight)
};
RandomlySwitchFourCells(Grid, randomPoint);
}
}
/// <summary>
/// Gets the right and bottom neighbours of the point given with the coordinates <see cref="p" />
/// in the <see cref="Grid" />.
/// </summary>
private KpzNeighbours GetNeighbours(KpzNode[,] grid, KpzCoords p)
{
KpzNeighbours toReturn;
toReturn.nxCoords = new KpzCoords
{
x = (p.x < GridWidth - 1) ? p.x + 1 : 0,
y = p.y
};
toReturn.nyCoords = new KpzCoords
{
x = p.x,
y = (p.y < GridHeight - 1) ? p.y + 1 : 0
};
toReturn.nx = grid[toReturn.nxCoords.x, toReturn.nxCoords.y];
toReturn.ny = grid[toReturn.nyCoords.x, toReturn.nyCoords.y];
return(toReturn);
}
/// <summary>
/// Adds a deep copy of the grid into the current <see cref="KpzStateLogger" /> iteration, with cells
/// to highlight (<see cref="Center" /> and <see cref="Neighbours" />). If the values in the grid were updated,
/// they are highlighted with a green color, else they are highlighted with a red color, based on the parameter
/// value of <see cref="ChangedGrid" />.
/// </summary>
public void AddKpzAction(string Description, KpzNode[,] Grid, KpzCoords Center,
KpzNeighbours Neighbours, bool ChangedGrid)
{
var highlightedCoords = new List <KpzCoords>();
highlightedCoords.Add(new KpzCoords {
x = Center.x, y = Center.y
});
highlightedCoords.Add(new KpzCoords {
x = Neighbours.nxCoords.x, y = Neighbours.nxCoords.y
});
highlightedCoords.Add(new KpzCoords {
x = Neighbours.nyCoords.x, y = Neighbours.nyCoords.y
});
Iterations[Iterations.Count - 1].Actions.Add(new KpzAction
{
Description = Description,
Grid = CopyOfGrid(Grid),
HeightMap = new int[0, 0],
HightlightColor = (ChangedGrid) ? Color.LightGreen : Color.Salmon, // green or red
HighlightedCoords = highlightedCoords
});
}
