public static WayPoints FromPath(Path path) { WayPoints points = new WayPoints(); while (path != null && !path.Finished) { IGridCell current = path.GetNextWaypoint(); if (current != null) { points.Push(new HexPoint(current.X, current.Y)); points._goal = new HexPoint(current.X, current.Y); } } return points; }
/// <summary> /// Calculates a path from start to end. When no path can be found in /// reasonable time the search is aborted and an incomplete path is returned. /// When refresh is not set to true a cached path is returned where possible. /// </summary> /// <param name="start">start position in 2d map space</param> /// <param name="end">end position in 2d map space</param> /// <param name="refresh">force to recalculate the path</param> /// <returns></returns> public Path CalculatePath(Unit unit, HexPoint start, HexPoint end, bool refresh = false) { // swap points to calculate the path backwards (from end to start) HexPoint temp = end; end = start; start = temp; // Check whether the requested path is already known PathRequest request = new PathRequest(unit,start, end); if (!refresh && knownPaths.ContainsKey(request)) { return knownPaths[request].Copy(); } // priority queue of nodes that yet have to be explored sorted in // ascending order by node costs (F) PriorityQueue<PathNode> open = new PriorityQueue<PathNode>(); // list of nodes that have already been explored LinkedList<IGridCell> closed = new LinkedList<IGridCell>(); // start is to be explored first PathNode startNode = new PathNode(unit,null, map[start], end); open.Enqueue(startNode); int steps = 0; PathNode current; do { // abort if calculation is too expensive if (++steps > stepLimit) return null; // examine the cheapest node among the yet to be explored current = open.Dequeue(); // Finish? if (current.Cell.Matches(end)) { // paths which lead to the requested goal are cached for reuse Path path = new Path(current); if (knownPaths.ContainsKey(request)) { knownPaths[request] = path.Copy(); } else { knownPaths.Add(request, path.Copy()); } return path; } // Explore all neighbours of the current cell ICollection<IGridCell> neighbours = map.GetNeighbourCells(current.Cell); foreach (IGridCell cell in neighbours) { // discard nodes that are not of interest if (closed.Contains(cell) || (cell.Matches(end) == false && !cell.IsWalkable(unit))) { continue; } // successor is one of current's neighbours PathNode successor = new PathNode(unit,current, cell, end); PathNode contained = open.Find(successor); if (contained != null && successor.F >= contained.F) { // This cell is already in the open list represented by // another node that is cheaper continue; } else if (contained != null && successor.F < contained.F) { // This cell is already in the open list but on a more expensive // path -> "integrate" the node into the current path contained.Predecessor = current; contained.Update(); open.Update(contained); } else { // The cell is not in the open list and therefore still has to // be explored open.Enqueue(successor); } } // add current to the list of the already explored nodes closed.AddLast(current.Cell); } while (open.Peek() != null); return null; }
///// <summary> ///// Just for debugging: Renders the complete path from beginning. ///// </summary> //[Conditional("DEBUG")] //public void DrawPath() //{ // DrawPath(start, start.Predecessor); //} ///// <summary> ///// Recursive function for rendering a path segment as a yellow line. ///// </summary> ///// <param name="from">Start node</param> ///// <param name="to">End node</param> //[Conditional("DEBUG")] //private void DrawPath(PathNode from, PathNode to) //{ // if (to == null) return; // DebugDisplay.Instance.DrawLine(from.Cell.Position3D, to.Cell.Position3D, from == start ? Color.Red : Color.Yellow); // DrawPath(to, to.Predecessor); //} /// <summary> /// Copies this instance of the path. /// </summary> /// <returns></returns> public Path Copy() { Path copy = new Path(start); return copy; }