/// <summary>
/// Get an IEnumerable of outermost border Cells in a square area around the center Cell up to the specified distance
/// Taken from: https://github.com/FaronBracy/RogueSharp/blob/master/RogueSharp/Map.cs
/// </summary>
/// <param name="center">center Cell</param>
/// <param name="distance">The number of Cells to get in each direction from the center Cell</param>
/// <returns>IEnumerable of outermost border Cells in a square area around the center Cell</returns>
public static IEnumerable <ICell> BorderCellsInSquare(ICellContainer map, Vector2Int center, int distance)
{
Vector2Int min = new Vector2Int(
Math.Max(0, center.x - distance),
Math.Max(0, center.y - distance)
);
Vector2Int max = new Vector2Int(
Math.Min(map.Width - 1, center.x + distance),
Math.Min(map.Height - 1, center.y + distance)
);
List <ICell> borderCells = new List <ICell>();
for (int x = min.x; x <= max.x; x++)
{
borderCells.Add(map.CellAt(x, min.y));
borderCells.Add(map.CellAt(x, max.y));
}
for (int y = min.y + 1; y <= max.y - 1; y++)
{
borderCells.Add(map.CellAt(min.x, y));
borderCells.Add(map.CellAt(max.x, y));
}
ICell centerCell = map.CellAt(center);
borderCells.Remove(centerCell);
return(borderCells);
}
/// <summary>
/// Compute field of view in the given map
/// </summary>
/// <param name="map">map that will receive the fov settings</param>
/// <param name="origin">fov origin</param>
/// <param name="radius">fov radius</param>
public static void Compute(ICellContainer map, Vector2Int origin, int radius)
{
ClearFovInCells(map);
foreach (ICell borderCell in MapNavigationUtils.BorderCellsInSquare(map, origin, radius))
{
foreach (ICell cell in MapNavigationUtils.CellsAlongLine(map, origin, borderCell.position))
{
if (Math.Abs(Vector2Int.Distance(cell.position, origin)) > radius)
{
break;
}
if (!cell.isSightBlocked)
{
map.CellAt(cell.position).isInFov = true;
}
else
{
// light walls
map.CellAt(cell.position).isInFov = true;
break;
}
}
}
PostProcessFov(map, origin, radius);
}
private static void PostProcessFovQuadrant(ICellContainer map, ICell cell, Quadrant quadrant)
{
ICell c1, c2;
switch (quadrant)
{
case Quadrant.NE:
{
c1 = map.CellAt(cell.position + Vector2Int.up);
c2 = map.CellAt(cell.position + Vector2Int.left);
break;
}
case Quadrant.SE:
{
c1 = map.CellAt(cell.position + Vector2Int.down);
c2 = map.CellAt(cell.position + Vector2Int.left);
break;
}
case Quadrant.SW:
{
c1 = map.CellAt(cell.position + Vector2Int.down);
c2 = map.CellAt(cell.position + Vector2Int.right);
break;
}
case Quadrant.NW:
{
c1 = map.CellAt(cell.position + Vector2Int.up);
c2 = map.CellAt(cell.position + Vector2Int.right);
break;
}
default:
throw new Exception("Unexpected quadrant");
}
ICell cx = map.CellAt(c2.position.x, c1.position.y);
if (!cell.isInFov && cell.isSightBlocked)
{
if ((!c1.isSightBlocked && c1.isInFov) || (!c2.isSightBlocked && c2.isInFov) ||
(!cx.isSightBlocked && cx.isInFov))
{
cell.isInFov = true;
}
}
}
private static void ClearFovInCells(ICellContainer map)
{
for (int x = 0; x < map.Width; x++)
{
for (int y = 0; y < map.Height; y++)
{
map.CellAt(x, y).isInFov = false;
}
}
}
/// <summary>
/// Get an IEnumerable of Cells in a square area around the center Cell up to the specified distance
/// </summary>
/// <param name="center">location of the center Cell</param>
/// <param name="distance">The number of Cells to get in each direction from the center Cell</param>
/// <returns>IEnumerable of Cells in a square area around the center Cell</returns>
public static IEnumerable <ICell> CellsInSquare(ICellContainer map, Vector2Int center, int distance)
{
Vector2Int min = new Vector2Int(
Math.Max(0, center.x - distance),
Math.Max(0, center.y - distance)
);
Vector2Int max = new Vector2Int(
Math.Min(map.Width - 1, center.x + distance),
Math.Min(map.Height - 1, center.y + distance)
);
for (int x = min.x; x <= max.x; x++)
{
for (int y = min.y; y <= max.y; y++)
{
yield return(map.CellAt(x, y));
}
}
}
/// <summary>
/// Get an IEnumerable of Cells in a line from the Origin Cell to the Destination Cell
/// The resulting IEnumerable includes the Origin and Destination Cells
/// Uses Bresenham's line algorithm to determine which Cells are in the closest approximation to a straight line between the two Cells
/// </summary>
/// <param name="origin">location of the Origin Cell at the start of the line</param>
/// <param name="destination">location of the Destination Cell at the end of the line</param>
/// <returns>IEnumerable of Cells in a line from the Origin Cell to the Destination Cell which includes the Origin and Destination Cells</returns>
public static IEnumerable <ICell> CellsAlongLine(ICellContainer map, Vector2Int origin, Vector2Int destination)
{
Vector2Int maxPosition = new Vector2Int(map.Width - 1, map.Height - 1);
origin.Clamp(Vector2Int.zero, maxPosition);
destination.Clamp(Vector2Int.zero, maxPosition);
Vector2Int d = new Vector2Int(
Math.Abs(destination.x - origin.x),
Math.Abs(destination.y - origin.y)
);
Vector2Int s = new Vector2Int(
origin.x < destination.x ? 1 : -1,
origin.y < destination.y ? 1 : -1
);
int err = d.x - d.y;
while (true)
{
yield return(map.CellAt(origin));
if (origin == destination)
{
break;
}
int e2 = 2 * err;
if (e2 > -d.y)
{
err = err - d.y;
origin.x += s.x;
}
if (e2 < d.x)
{
err = err + d.x;
origin.y += s.y;
}
}
}