private bool AddShadow(FovShadow shadow)
{
int index;
for (index = 0; index < shadows.Count; index++)
{
// See if we are at the insertion point for this shadow.
if (shadows[index].Start > shadow.Start)
{
// Break out and handle inserting below.
break;
}
}
// The new shadow is going here. See if it overlaps the previous or next.
var overlapsPrev = ((index > 0) && (shadows[index - 1].End > shadow.Start));
var overlapsNext = ((index < shadows.Count) && (shadows[index].Start < shadow.End));
// Insert and unify with overlapping shadows.
if (overlapsNext)
{
if (overlapsPrev)
{
// Overlaps both, so unify one and delete the other.
shadows[index - 1].End = Math.Max(shadows[index - 1].End, shadows[index].End);
shadows.RemoveAt(index);
}
else
{
// Just overlaps the next shadow, so unify it with that.
shadows[index].Start = Math.Min(shadows[index].Start, shadow.Start);
}
}
else
{
if (overlapsPrev)
{
// Just overlaps the previous shadow, so unify it with that.
shadows[index - 1].End = Math.Max(shadows[index - 1].End, shadow.End);
}
else
{
// Does not overlap anything, so insert.
shadows.Insert(index, shadow);
}
}
// See if we are now shadowing everything.
return((shadows.Count == 1) && (shadows[0].Start == 0) && (shadows[0].End == 1));
}
private int RefreshOctant(VectorBase start, int octant)
{
var numExplored = 0;
VectorBase rowInc = null;
VectorBase colInc = null;
// Figure out which direction to increment based on the octant. Octant 0
// starts at 12 - 2 o'clock, and octants proceed clockwise from there.
switch (octant)
{
case 0:
rowInc = new VectorBase(0, -1);
colInc = new VectorBase(1, 0);
break;
case 1:
rowInc = new VectorBase(1, 0);
colInc = new VectorBase(0, -1);
break;
case 2:
rowInc = new VectorBase(1, 0);
colInc = new VectorBase(0, 1);
break;
case 3:
rowInc = new VectorBase(0, 1);
colInc = new VectorBase(1, 0);
break;
case 4:
rowInc = new VectorBase(0, 1);
colInc = new VectorBase(-1, 0);
break;
case 5:
rowInc = new VectorBase(-1, 0);
colInc = new VectorBase(0, 1);
break;
case 6:
rowInc = new VectorBase(-1, 0);
colInc = new VectorBase(0, -1);
break;
case 7:
rowInc = new VectorBase(0, -1);
colInc = new VectorBase(-1, 0);
break;
}
if (rowInc == null || colInc == null)
{
throw new ArgumentNullException();
}
shadows = new List <FovShadow>();
var bounds = Stage.Bounds();
var fullShadow = false;
// Sweep through the rows ('rows' may be vertical or horizontal based on
// the incrementors). Start at row 1 to skip the center position.
for (var row = 1;; row++)
{
var pos = start + (rowInc * row);
// If we've traversed out of bounds, bail.
// Note: this improves performance, but works on the assumption that the
// starting tile of the FOV is in bounds.
if (!bounds.Contains(pos))
{
break;
}
for (var col = 0; col <= row; col++)
{
var blocksLight = false;
var visible = false;
FovShadow projection = null;
// If we know the entire row is in shadow, we don't need to be more
// specific.
if (!fullShadow)
{
blocksLight = !Stage[pos].IsTransparent;
projection = GetProjection(col, row);
visible = !IsInShadow(projection);
}
// Set the visibility of this tile.
if (Stage[pos].SetVisible(visible))
{
numExplored++;
}
// Add any opaque tiles to the shadow map.
if (blocksLight)
{
fullShadow = AddShadow(projection);
}
// Move to the next column.
pos += colInc;
// If we've traversed out of bounds, bail on this row.
// note: this improves performance, but works on the assumption that
// the starting tile of the FOV is in bounds.
if (!bounds.Contains(pos))
{
break;
}
}
}
return(numExplored);
}
public bool Contains(FovShadow projection)
{
return((Start <= projection.Start) && (End >= projection.End));
}
private bool IsInShadow(FovShadow projection)
{
// Check the shadow list.
return(shadows.Any(shadow => shadow.Contains(projection)));
}