private bool CheckField(CLikeIterator <fieldT> currentField)
{
// If the two slopes are colinear, and if they pass through either
// extremity, remove the field of view.
fieldT currFld = currentField.GetCurrent();
bool ret = false;
if (currFld.m_Shallow.DoesContain(currFld.m_Steep.m_Near) &&
currFld.m_Shallow.DoesContain(currFld.m_Steep.m_Far) &&
(currFld.m_Shallow.DoesContain(new Point2I(0, 1)) || currFld.m_Shallow
.DoesContain(new Point2I(1, 0))))
{
currentField.RemoveCurrent();
ret = true;
}
return(ret);
}
private void CalculateFovQuadrant(fovStateT state)
{
LinkedList <bumpT> steepBumps = new LinkedList <bumpT>();
LinkedList <bumpT> shallowBumps = new LinkedList <bumpT>();
// activeFields is sorted from shallow-to-steep.
LinkedList <fieldT> activeFields = new LinkedList <fieldT>();
activeFields.AddLast(new fieldT());
activeFields.Last.Value.m_Shallow.m_Near = new Point2I(0, 1);
activeFields.Last.Value.m_Shallow.m_Far = new Point2I(state.m_Extent.m_X, 0);
activeFields.Last.Value.m_Steep.m_Near = new Point2I(1, 0);
activeFields.Last.Value.m_Steep.m_Far = new Point2I(0, state.m_Extent.m_Y);
Point2I dest = new Point2I(0, 0);
// Visit the source square exactly once (in quadrant 1).
if (state.m_Quadrant.m_X == 1 && state.m_Quadrant.m_Y == 1)
{
ActIsBlocked(state, dest);
}
CLikeIterator <fieldT> currentField = new CLikeIterator <fieldT>(
activeFields.First);
int i = 0;
int j = 0;
int maxI = state.m_Extent.m_X + state.m_Extent.m_Y;
// For each square outline
for (i = 1; i <= maxI && activeFields.Count > 0; ++i)
{
int startJ = Max(0, i - state.m_Extent.m_X);
int maxJ = Min(i, state.m_Extent.m_Y);
// Visit the nodes in the outline
for (j = startJ; j <= maxJ && !currentField.IsAtEnd(); ++j)
{
dest.m_X = i - j;
dest.m_Y = j;
VisitSquare(state, dest, currentField, steepBumps,
shallowBumps, activeFields);
}
currentField = new CLikeIterator <fieldT>(activeFields.First);
}
}
private void VisitSquare(fovStateT state, Point2I dest,
CLikeIterator <fieldT> currentField, LinkedList <bumpT> steepBumps,
LinkedList <bumpT> shallowBumps, LinkedList <fieldT> activeFields)
{
// The top-left and bottom-right corners of the destination square.
Point2I topLeft = new Point2I(dest.m_X, dest.m_Y + 1);
Point2I bottomRight = new Point2I(dest.m_X + 1, dest.m_Y);
while (!currentField.IsAtEnd() &&
currentField.GetCurrent().m_Steep
.IsBelowOrContains(bottomRight))
{
// case ABOVE
// The square is in case 'above'. This means that it is ignored
// for the currentField. But the steeper fields might need it.
currentField.GotoNext();
}
if (currentField.IsAtEnd())
{
// The square was in case 'above' for all fields. This means that
// we no longer care about it or any squares in its diagonal rank.
return;
}
// Now we check for other cases.
if (currentField.GetCurrent().m_Shallow.IsAboveOrContains(topLeft))
{
// case BELOW
// The shallow line is above the extremity of the square, so that
// square is ignored.
return;
}
// The square is between the lines in some way. This means that we
// need to visit it and determine whether it is blocked.
bool isBlocked = ActIsBlocked(state, dest);
if (!isBlocked)
{
// We don't care what case might be left, because this square does
// not obstruct.
return;
}
if (currentField.GetCurrent().m_Shallow.IsAbove(bottomRight) &&
currentField.GetCurrent().m_Steep.IsBelow(topLeft))
{
// case BLOCKING
// Both lines intersect the square. This current field has ended.
currentField.RemoveCurrent();
}
else if (currentField.GetCurrent().m_Shallow.IsAbove(bottomRight))
{
// case SHALLOW BUMP
// The square intersects only the shallow line.
AddShallowBump(topLeft, currentField.GetCurrent(), steepBumps,
shallowBumps);
CheckField(currentField);
}
else if (currentField.GetCurrent().m_Steep.IsBelow(topLeft))
{
// case STEEP BUMP
// The square intersects only the steep line.
AddSteepBump(bottomRight, currentField.GetCurrent(), steepBumps,
shallowBumps);
CheckField(currentField);
}
else
{
// case BETWEEN
// The square intersects neither line. We need to split into two
// fields.
fieldT steeperField = currentField.GetCurrent();
fieldT shallowerField = new fieldT(currentField.GetCurrent());
currentField.InsertBeforeCurrent(shallowerField);
AddSteepBump(bottomRight, shallowerField, steepBumps, shallowBumps);
currentField.GotoPrevious();
if (!CheckField(currentField)) // did not remove
{
currentField.GotoNext(); // point to the original element
}
AddShallowBump(topLeft, steeperField, steepBumps, shallowBumps);
CheckField(currentField);
}
}
