private static void OptimizeSegment(int startIndex, int endIndex,
StopFunction stopFunction,
IReadOnlyCollection <Point> inputPath,
ICollection <Point> result)
{
Point startPoint = inputPath.ElementAt(startIndex);
Point endPoint = inputPath.ElementAt(endIndex);
// if this segment is unblocked, return start + end points
if (LineRasterizer.IsUnblocked(startPoint, endPoint, stopFunction))
{
result.Add(inputPath.ElementAt(startIndex));
result.Add(inputPath.ElementAt(endIndex));
}
else // otherwise subdivide segment in two, and process them
{
int halfIndex = startIndex + (endIndex - startIndex) / 2 + 1;
OptimizeSegment(startIndex, halfIndex - 1, stopFunction, inputPath, result);
OptimizeSegment(halfIndex, endIndex, stopFunction, inputPath, result);
}
}
private static void OptimizeSegment(Int32 startIndex, Int32 endIndex,
StopFunction <Vector2> stopFunction,
List <Vector2> inputPath,
ICollection <Vector2> result)
{
Vector2 startPosition = inputPath.ElementAt(startIndex);
Vector2 endPosition = inputPath.ElementAt(endIndex);
// if this segment is unblocked, return start + end points
if (LineRasterizer.IsUnblocked(startPosition, endPosition, stopFunction))
{
result.Add(inputPath.ElementAt(startIndex));
result.Add(inputPath.ElementAt(endIndex));
}
else // otherwise subdivide segment in two, and process them
{
Int32 halfIndex = startIndex + (endIndex - startIndex) / 2 + 1;
OptimizeSegment(startIndex, halfIndex - 1, stopFunction, inputPath, result);
OptimizeSegment(halfIndex, endIndex, stopFunction, inputPath, result);
}
}
/// <summary>
/// This optimization should be used on limited point set (see <see cref="TooMuchPoints"/>).
/// It searches for unblocked connection from start to end point. The end point is moved,
/// until the connection is found (at worst the next connection = no optimizaton). If found
/// the start point is moved to this new point, and end point is reset to end point.
/// This continues unless we're done.
/// </summary>
/// <param name="inputPath">The input path.</param>
/// <param name="stopFunction">The stop function.</param>
/// <param name="optimizedPath">The optimized path.</param>
/// <param name="optimizedPivotPoints">The optimized pivot points.</param>
protected static void VisibilityOptimization(IReadOnlyCollection <Point> inputPath,
StopFunction stopFunction,
out IReadOnlyCollection <Point> optimizedPath,
out IReadOnlyCollection <Point> optimizedPivotPoints)
{
// creates result path
List <Point> result = new List <Point>();
// determines master point (one tested from), and last point (to detect cycle end)
int masterIndex = 0;
int lastIndex = inputPath.Count - 1;
Point masterPoint = inputPath.ElementAt(masterIndex);
// adds first point
result.Add(masterPoint);
do // performs optimization loop
{
// starts at last points and work its way to the start point
for (int index = Math.Min(OptimizationStep, lastIndex); index >= 0; index--)
{
int referenceIndex = Math.Min(masterIndex + index, lastIndex);
Point referencePoint = inputPath.ElementAt(referenceIndex);
// if reference point is visible from master point (or next, which is assumed as visible) reference point becomes master
if (referenceIndex == masterIndex + 1 || LineRasterizer.IsUnblocked(masterPoint, referencePoint, stopFunction))
{
// switches reference point as master, adding master to an optimized path
masterPoint = inputPath.ElementAt(referenceIndex);
masterIndex = referenceIndex;
result.Add(masterPoint);
break;
}
}
} while (masterIndex < lastIndex); // if we're on the last point -> terminate
// returns the optimized path
optimizedPath = result;
optimizedPivotPoints = result;
}
protected void AddRectangleToCache(Rectangle rectangle)
{
// set bits to each point inside the rectangle
if (AreHollowAreasMinimized)
{
int offset = GetOffset(rectangle.Left, rectangle.Top);
for (int y = 0; y < rectangle.Height; y++)
{
for (int x = 0; x < rectangle.Width; x++)
{
Cache.Set(offset + x, true);
}
offset += Width;
}
}
else // set bits of hollow rectangle only
{
// sides (top/right/bottom/left)
foreach (Point point in LineRasterizer.EnumerateHorizontalLine(rectangle.Left, rectangle.Right - 2, rectangle.Top))
{
SetCacheBit(point.X, point.Y);
}
foreach (Point point in LineRasterizer.EnumerateVerticalLine(rectangle.Right - 1, rectangle.Top, rectangle.Bottom - 2))
{
SetCacheBit(point.X, point.Y);
}
foreach (Point point in LineRasterizer.EnumerateHorizontalLine(rectangle.Left + 1, rectangle.Right - 1, rectangle.Bottom - 1))
{
SetCacheBit(point.X, point.Y);
}
foreach (Point point in LineRasterizer.EnumerateVerticalLine(rectangle.Left, rectangle.Top + 1, rectangle.Bottom - 1))
{
SetCacheBit(point.X, point.Y);
}
}
}
/// <summary>
/// See <see cref="BasePathfinder.OnTryFindPath"/> for more details.
/// </summary>
protected override bool OnTryFindPath(Point startPoint, Point endPoint,
StopFunction stopFunction,
out IReadOnlyCollection <Point> path,
out IReadOnlyCollection <Point> pivotPoints,
bool optimize = true)
{
// prepares main parameters
bool result = false;
List <Point> pointList = new List <Point>();
// detects all the path segments that are passable
IReadOnlyList <PathSegment> segments = LineRasterizer.ScanPathSegments(startPoint, endPoint, stopFunction);
int segmentIndex = 0;
bool running = true;
while (running)
{
// gets this segment
PathSegment segment = segments[segmentIndex];
Point collisionPoint = segment.LastPoint;
// adds already found points to a final path
pointList.Add(segment.FirstPoint);
pointList.Add(segment.LastPoint);
// we have arrived at destination, we're done here
if (collisionPoint == endPoint)
{
result = true;
break;
}
// cirumvents the obstacle from both sides
EvasionObstacleInfo obstacleInfo;
// tries to circumvent the obstacle from both sides (left/right) to determine which on is shorter
if (TryScanObstacle(collisionPoint, segment.Direction, stopFunction, segments, segmentIndex, out obstacleInfo))
{
// adds better route points to our result structures, advances to the latest segment
segmentIndex += obstacleInfo.SegmentIndex + 1;
// determines left/right side paths step counts
int leftPathStepCount = obstacleInfo.LeftStepCount;
int rightPathStepCount = obstacleInfo.TotalStepCount - leftPathStepCount;
// determines short path
IEnumerable <Point> shorterPath = leftPathStepCount < rightPathStepCount?
obstacleInfo.PivotPoints.Take(obstacleInfo.LefPointCount) :
obstacleInfo.PivotPoints.Skip(obstacleInfo.LefPointCount).Reverse();
// adds this path to overall path
pointList.AddRange(shorterPath);
}
else // path not found
{
running = false;
}
}
// returns the found path
pivotPoints = pointList;
path = pointList;
return(result);
}