/// <summary>
/// Generate a field of view within this cell map
/// </summary>
/// <param name="fromPoint"></param>
/// <param name="maxRange"></param>
/// <param name="transparencyCondition"></param>
/// <param name="outGrid"></param>
/// <param name="visibleValue">The value to set in the output grid to indicate visibility</param>
public static void FieldOfView <E, T>(this ICellMap <T> grid, Vector fromPoint, double maxRange, Func <T, bool> transparencyCondition,
ICellMap <E> outGrid, E visibleValue)
{
double tolerance = 0.00001;
double maxRangeSqd = maxRange * maxRange;
AngleIntervals shadows = new AngleIntervals();
IList <int> cIs = grid.CellsOrderedByDistance(fromPoint, Math.Ceiling(maxRange));
int current = grid.IndexAt(fromPoint);
foreach (int index in cIs)
{
Vector centroid = grid.CellPosition(index);
double distSqd = fromPoint.DistanceToSquared(centroid);
if (distSqd > maxRangeSqd)
{
return; //Shortcut, reached end of range (?)
}
T item = grid[index];
bool opaque = !transparencyCondition.Invoke(item);
if ((opaque || !shadows.IsEmpty) && index != current)
{
double angle = fromPoint.AngleTo(centroid).NormalizeTo2PI();
if (!shadows.isInsideRegion(angle, tolerance))
{
//Is visible:
if (!opaque)
{
outGrid[index] = visibleValue;
}
}
if (opaque)
{
//Add to shadows:
Angle mindA = 0;
Angle maxdA = 0;
for (int i = 0; i < grid.VertexCount(index); i++)
{
Vector vertex = grid.CellVertex(index, i);
Angle dA = (fromPoint.AngleTo(vertex) - angle).Normalize();
if (dA < mindA)
{
mindA = dA;
}
if (dA > maxdA)
{
maxdA = dA;
}
}
mindA *= 0.9;
maxdA *= 0.9;
Angle start = (angle + mindA).NormalizeTo2PI();
Angle end = (angle + maxdA).NormalizeTo2PI();
shadows.addRegion(start, end);
//Shortcut: end if full:
if (shadows.IsFull)
{
return;
}
}
}
else
{
outGrid[index] = visibleValue;
}
}
}