Example #1
0
        private static void identifySuccessors(JumpPointParam iParam, Node iNode)
        {
            HeuristicDelegate tHeuristic = iParam.HeuristicFunc;
            List <Node>       tOpenList  = iParam.openList;
            int    tEndX = iParam.EndNode.x;
            int    tEndY = iParam.EndNode.y;
            LPoint tNeighbor;
            LPoint?tJumpPoint;
            Node   tJumpNode;

            List <LPoint> tNeighbors = findNeighbors(iParam, iNode);

            for (int i = 0; i < tNeighbors.Count; i++)
            {
                tNeighbor = tNeighbors[i];
                if (iParam.UseRecursive)
                {
                    tJumpPoint = jump(iParam, tNeighbor.x, tNeighbor.y, iNode.x, iNode.y);
                }
                else
                {
                    tJumpPoint = jumpLoop(iParam, tNeighbor.x, tNeighbor.y, iNode.x, iNode.y);
                }
                if (tJumpPoint != null)
                {
                    tJumpNode = iParam.SearchGrid.GetNodeAt(tJumpPoint.Value.x, tJumpPoint.Value.y);
                    if (tJumpNode == null)
                    {
                        if (iParam.EndNode.x == tJumpPoint.Value.x && iParam.EndNode.y == tJumpPoint.Value.y)
                        {
                            tJumpNode = iParam.SearchGrid.GetNodeAt(tJumpPoint.Value);
                        }
                    }
                    if (tJumpNode.isClosed)
                    {
                        continue;
                    }
                    // include distance, as parent may not be immediately adjacent:
                    float tCurNodeToJumpNodeLen = tHeuristic(Math.Abs(tJumpPoint.Value.x - iNode.x), Math.Abs(tJumpPoint.Value.y - iNode.y));
                    float tStartToJumpNodeLen   = iNode.startToCurNodeLen + tCurNodeToJumpNodeLen; // next `startToCurNodeLen` value

                    if (!tJumpNode.isOpened || tStartToJumpNodeLen < tJumpNode.startToCurNodeLen)
                    {
                        tJumpNode.startToCurNodeLen        = tStartToJumpNodeLen;
                        tJumpNode.heuristicCurNodeToEndLen = (tJumpNode.heuristicCurNodeToEndLen == null ? tHeuristic(Math.Abs(tJumpPoint.Value.x - tEndX), Math.Abs(tJumpPoint.Value.y - tEndY)) : tJumpNode.heuristicCurNodeToEndLen);
                        tJumpNode.heuristicStartToEndLen   = tJumpNode.startToCurNodeLen + tJumpNode.heuristicCurNodeToEndLen.Value;
                        tJumpNode.parent = iNode;

                        if (!tJumpNode.isOpened)
                        {
                            tOpenList.Add(tJumpNode);
                            tJumpNode.isOpened = true;
                        }
                    }
                }
            }
        }
Example #2
0
        public static List <LPoint> FindPath(JumpPointParam iParam)
        {
            List <Node> tOpenList  = iParam.openList;
            Node        tStartNode = iParam.StartNode;
            Node        tEndNode   = iParam.EndNode;
            Node        tNode;
            bool        revertEndNodeWalkable = false;

            // set the `g` and `f` value of the start node to be 0
            tStartNode.startToCurNodeLen      = 0;
            tStartNode.heuristicStartToEndLen = 0;

            // push the start node into the open list
            tOpenList.Add(tStartNode);
            tStartNode.isOpened = true;

            if (iParam.AllowEndNodeUnWalkable && !iParam.SearchGrid.IsWalkableAt(tEndNode.x, tEndNode.y))
            {
                iParam.SearchGrid.SetWalkableAt(tEndNode.x, tEndNode.y, true);
                revertEndNodeWalkable = true;
            }

            // while the open list is not empty
            while (tOpenList.Count > 0)
            {
                // pop the position of node which has the minimum `f` value.
                tOpenList.Sort();
                tNode = (Node)tOpenList[tOpenList.Count - 1];
                tOpenList.RemoveAt(tOpenList.Count - 1);
                tNode.isClosed = true;

                if (tNode.Equals(tEndNode))
                {
                    if (revertEndNodeWalkable)
                    {
                        iParam.SearchGrid.SetWalkableAt(tEndNode.x, tEndNode.y, false);
                    }
                    return(Node.Backtrace(tNode)); // rebuilding path
                }

                identifySuccessors(iParam, tNode);
            }

            if (revertEndNodeWalkable)
            {
                iParam.SearchGrid.SetWalkableAt(tEndNode.x, tEndNode.y, false);
            }

            // fail to find the path
            return(new List <LPoint>());
        }
Example #3
0
        public JumpPointParam(JumpPointParam b)
        {
            m_heuristic = b.m_heuristic;
            m_allowEndNodeUnWalkable = b.m_allowEndNodeUnWalkable;
            m_crossAdjacentPoint     = b.m_crossAdjacentPoint;
            m_crossCorner            = b.m_crossCorner;

            openList = new List <Node>(b.openList);

            m_searchGrid   = b.m_searchGrid;
            m_startNode    = b.m_startNode;
            m_endNode      = b.m_endNode;
            m_useRecursive = b.m_useRecursive;
        }
Example #4
0
        private static List <LPoint> findNeighbors(JumpPointParam iParam, Node iNode)
        {
            Node          tParent = (Node)iNode.parent;
            int           tX = iNode.x;
            int           tY = iNode.y;
            int           tPx, tPy, tDx, tDy;
            List <LPoint> tNeighbors = new List <LPoint>();
            List <Node>   tNeighborNodes;
            Node          tNeighborNode;

            // directed pruning: can ignore most neighbors, unless forced.
            if (tParent != null)
            {
                tPx = tParent.x;
                tPy = tParent.y;
                // get the normalized direction of travel
                tDx = (tX - tPx) / Math.Max(Math.Abs(tX - tPx), 1);
                tDy = (tY - tPy) / Math.Max(Math.Abs(tY - tPy), 1);

                if (iParam.CrossCorner)
                {
                    // search diagonally
                    if (tDx != 0 && tDy != 0)
                    {
                        if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy))
                        {
                            tNeighbors.Add(new LPoint(tX, tY + tDy));
                        }
                        if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY))
                        {
                            tNeighbors.Add(new LPoint(tX + tDx, tY));
                        }

                        if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY + tDy))
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy) || iParam.SearchGrid.IsWalkableAt(tX + tDx, tY))
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY + tDy));
                            }
                            else if (iParam.CrossAdjacentPoint)
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY + tDy));
                            }
                        }

                        if (iParam.SearchGrid.IsWalkableAt(tX - tDx, tY + tDy))
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy) && !iParam.SearchGrid.IsWalkableAt(tX - tDx, tY))
                            {
                                tNeighbors.Add(new LPoint(tX - tDx, tY + tDy));
                            }
                            else if (iParam.CrossAdjacentPoint)
                            {
                                tNeighbors.Add(new LPoint(tX - tDx, tY + tDy));
                            }
                        }

                        if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY - tDy))
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY) && !iParam.SearchGrid.IsWalkableAt(tX, tY - tDy))
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY - tDy));
                            }
                            else if (iParam.CrossAdjacentPoint)
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY - tDy));
                            }
                        }
                    }
                    // search horizontally/vertically
                    else
                    {
                        if (tDx == 0)
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy))
                            {
                                tNeighbors.Add(new LPoint(tX, tY + tDy));

                                if (iParam.SearchGrid.IsWalkableAt(tX + 1, tY + tDy) && !iParam.SearchGrid.IsWalkableAt(tX + 1, tY))
                                {
                                    tNeighbors.Add(new LPoint(tX + 1, tY + tDy));
                                }
                                if (iParam.SearchGrid.IsWalkableAt(tX - 1, tY + tDy) && !iParam.SearchGrid.IsWalkableAt(tX - 1, tY))
                                {
                                    tNeighbors.Add(new LPoint(tX - 1, tY + tDy));
                                }
                            }
                            else if (iParam.CrossAdjacentPoint)
                            {
                                if (iParam.SearchGrid.IsWalkableAt(tX + 1, tY + tDy) && !iParam.SearchGrid.IsWalkableAt(tX + 1, tY))
                                {
                                    tNeighbors.Add(new LPoint(tX + 1, tY + tDy));
                                }
                                if (iParam.SearchGrid.IsWalkableAt(tX - 1, tY + tDy) && !iParam.SearchGrid.IsWalkableAt(tX - 1, tY))
                                {
                                    tNeighbors.Add(new LPoint(tX - 1, tY + tDy));
                                }
                            }
                        }
                        else
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY))
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY));

                                if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY + 1) && !iParam.SearchGrid.IsWalkableAt(tX, tY + 1))
                                {
                                    tNeighbors.Add(new LPoint(tX + tDx, tY + 1));
                                }
                                if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY - 1) && !iParam.SearchGrid.IsWalkableAt(tX, tY - 1))
                                {
                                    tNeighbors.Add(new LPoint(tX + tDx, tY - 1));
                                }
                            }
                            else if (iParam.CrossAdjacentPoint)
                            {
                                if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY + 1) && !iParam.SearchGrid.IsWalkableAt(tX, tY + 1))
                                {
                                    tNeighbors.Add(new LPoint(tX + tDx, tY + 1));
                                }
                                if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY - 1) && !iParam.SearchGrid.IsWalkableAt(tX, tY - 1))
                                {
                                    tNeighbors.Add(new LPoint(tX + tDx, tY - 1));
                                }
                            }
                        }
                    }
                }
                else // if(!iParam.CrossCorner)
                {
                    // search diagonally
                    if (tDx != 0 && tDy != 0)
                    {
                        if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy))
                        {
                            tNeighbors.Add(new LPoint(tX, tY + tDy));
                        }
                        if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY))
                        {
                            tNeighbors.Add(new LPoint(tX + tDx, tY));
                        }

                        if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY + tDy))
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy) && iParam.SearchGrid.IsWalkableAt(tX + tDx, tY))
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY + tDy));
                            }
                        }

                        if (iParam.SearchGrid.IsWalkableAt(tX - tDx, tY + tDy))
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy) && iParam.SearchGrid.IsWalkableAt(tX - tDx, tY))
                            {
                                tNeighbors.Add(new LPoint(tX - tDx, tY + tDy));
                            }
                        }

                        if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY - tDy))
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY - tDy) && iParam.SearchGrid.IsWalkableAt(tX + tDx, tY))
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY - tDy));
                            }
                        }
                    }
                    // search horizontally/vertically
                    else
                    {
                        if (tDx == 0)
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY + tDy))
                            {
                                tNeighbors.Add(new LPoint(tX, tY + tDy));

                                if (iParam.SearchGrid.IsWalkableAt(tX + 1, tY + tDy) && iParam.SearchGrid.IsWalkableAt(tX + 1, tY))
                                {
                                    tNeighbors.Add(new LPoint(tX + 1, tY + tDy));
                                }
                                if (iParam.SearchGrid.IsWalkableAt(tX - 1, tY + tDy) && iParam.SearchGrid.IsWalkableAt(tX - 1, tY))
                                {
                                    tNeighbors.Add(new LPoint(tX - 1, tY + tDy));
                                }
                            }
                            if (iParam.SearchGrid.IsWalkableAt(tX + 1, tY))
                            {
                                tNeighbors.Add(new LPoint(tX + 1, tY));
                            }
                            if (iParam.SearchGrid.IsWalkableAt(tX - 1, tY))
                            {
                                tNeighbors.Add(new LPoint(tX - 1, tY));
                            }
                        }
                        else
                        {
                            if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY))
                            {
                                tNeighbors.Add(new LPoint(tX + tDx, tY));

                                if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY + 1) && iParam.SearchGrid.IsWalkableAt(tX, tY + 1))
                                {
                                    tNeighbors.Add(new LPoint(tX + tDx, tY + 1));
                                }
                                if (iParam.SearchGrid.IsWalkableAt(tX + tDx, tY - 1) && iParam.SearchGrid.IsWalkableAt(tX, tY - 1))
                                {
                                    tNeighbors.Add(new LPoint(tX + tDx, tY - 1));
                                }
                            }
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY + 1))
                            {
                                tNeighbors.Add(new LPoint(tX, tY + 1));
                            }
                            if (iParam.SearchGrid.IsWalkableAt(tX, tY - 1))
                            {
                                tNeighbors.Add(new LPoint(tX, tY - 1));
                            }
                        }
                    }
                }
            }
            // return all neighbors
            else
            {
                tNeighborNodes = iParam.SearchGrid.GetNeighbors(iNode, iParam.CrossCorner, iParam.CrossAdjacentPoint);
                for (int i = 0; i < tNeighborNodes.Count; i++)
                {
                    tNeighborNode = tNeighborNodes[i];
                    tNeighbors.Add(new LPoint(tNeighborNode.x, tNeighborNode.y));
                }
            }

            return(tNeighbors);
        }
Example #5
0
        private static LPoint?jump(JumpPointParam iParam, int iX, int iY, int iPx, int iPy)
        {
            if (!iParam.SearchGrid.IsWalkableAt(iX, iY))
            {
                return(null);
            }
            else if (iParam.SearchGrid.GetNodeAt(iX, iY).Equals(iParam.EndNode))
            {
                return(new LPoint(iX, iY));
            }

            int    tDx = iX - iPx;
            int    tDy = iY - iPy;
            LPoint?jx  = null;
            LPoint?jy  = null;

            if (iParam.CrossCorner)
            {
                // check for forced neighbors
                // along the diagonal
                if (tDx != 0 && tDy != 0)
                {
                    if ((iParam.SearchGrid.IsWalkableAt(iX - tDx, iY + tDy) && !iParam.SearchGrid.IsWalkableAt(iX - tDx, iY)) ||
                        (iParam.SearchGrid.IsWalkableAt(iX + tDx, iY - tDy) && !iParam.SearchGrid.IsWalkableAt(iX, iY - tDy)))
                    {
                        return(new LPoint(iX, iY));
                    }
                }
                // horizontally/vertically
                else
                {
                    if (tDx != 0)
                    {
                        // moving along x
                        if ((iParam.SearchGrid.IsWalkableAt(iX + tDx, iY + 1) && !iParam.SearchGrid.IsWalkableAt(iX, iY + 1)) ||
                            (iParam.SearchGrid.IsWalkableAt(iX + tDx, iY - 1) && !iParam.SearchGrid.IsWalkableAt(iX, iY - 1)))
                        {
                            return(new LPoint(iX, iY));
                        }
                    }
                    else
                    {
                        if ((iParam.SearchGrid.IsWalkableAt(iX + 1, iY + tDy) && !iParam.SearchGrid.IsWalkableAt(iX + 1, iY)) ||
                            (iParam.SearchGrid.IsWalkableAt(iX - 1, iY + tDy) && !iParam.SearchGrid.IsWalkableAt(iX - 1, iY)))
                        {
                            return(new LPoint(iX, iY));
                        }
                    }
                }
                // when moving diagonally, must check for vertical/horizontal jump points
                if (tDx != 0 && tDy != 0)
                {
                    jx = jump(iParam, iX + tDx, iY, iX, iY);
                    jy = jump(iParam, iX, iY + tDy, iX, iY);
                    if (jx != null || jy != null)
                    {
                        return(new LPoint(iX, iY));
                    }
                }

                // moving diagonally, must make sure one of the vertical/horizontal
                // neighbors is open to allow the path
                if (iParam.SearchGrid.IsWalkableAt(iX + tDx, iY) || iParam.SearchGrid.IsWalkableAt(iX, iY + tDy))
                {
                    return(jump(iParam, iX + tDx, iY + tDy, iX, iY));
                }
                else if (iParam.CrossAdjacentPoint)
                {
                    return(jump(iParam, iX + tDx, iY + tDy, iX, iY));
                }
                else
                {
                    return(null);
                }
            }
            else //if (!iParam.CrossCorner)
            {
                // check for forced neighbors
                // along the diagonal
                if (tDx != 0 && tDy != 0)
                {
                    if ((iParam.SearchGrid.IsWalkableAt(iX + tDx, iY + tDy) && iParam.SearchGrid.IsWalkableAt(iX, iY + tDy) && !iParam.SearchGrid.IsWalkableAt(iX + tDx, iY)) ||
                        (iParam.SearchGrid.IsWalkableAt(iX + tDx, iY + tDy) && iParam.SearchGrid.IsWalkableAt(iX + tDx, iY) && !iParam.SearchGrid.IsWalkableAt(iX, iY + tDy)))
                    {
                        return(new LPoint(iX, iY));
                    }
                }
                // horizontally/vertically
                else
                {
                    if (tDx != 0)
                    {
                        // moving along x
                        if ((iParam.SearchGrid.IsWalkableAt(iX, iY + 1) && !iParam.SearchGrid.IsWalkableAt(iX - tDx, iY + 1)) ||
                            (iParam.SearchGrid.IsWalkableAt(iX, iY - 1) && !iParam.SearchGrid.IsWalkableAt(iX - tDx, iY - 1)))
                        {
                            return(new LPoint(iX, iY));
                        }
                    }
                    else
                    {
                        if ((iParam.SearchGrid.IsWalkableAt(iX + 1, iY) && !iParam.SearchGrid.IsWalkableAt(iX + 1, iY - tDy)) ||
                            (iParam.SearchGrid.IsWalkableAt(iX - 1, iY) && !iParam.SearchGrid.IsWalkableAt(iX - 1, iY - tDy)))
                        {
                            return(new LPoint(iX, iY));
                        }
                    }
                }


                // when moving diagonally, must check for vertical/horizontal jump points
                if (tDx != 0 && tDy != 0)
                {
                    jx = jump(iParam, iX + tDx, iY, iX, iY);
                    jy = jump(iParam, iX, iY + tDy, iX, iY);
                    if (jx != null || jy != null)
                    {
                        return(new LPoint(iX, iY));
                    }
                }

                // moving diagonally, must make sure both of the vertical/horizontal
                // neighbors is open to allow the path
                if (iParam.SearchGrid.IsWalkableAt(iX + tDx, iY) && iParam.SearchGrid.IsWalkableAt(iX, iY + tDy))
                {
                    return(jump(iParam, iX + tDx, iY + tDy, iX, iY));
                }
                else
                {
                    return(null);
                }
            }
        }
Example #6
0
        private static LPoint?jumpLoop(JumpPointParam iParam, int iX, int iY, int iPx, int iPy)
        {
            LPoint?retVal = null;
            Stack <JumpSnapshot> stack = new Stack <JumpSnapshot>();

            JumpSnapshot currentSnapshot = new JumpSnapshot();
            JumpSnapshot newSnapshot     = null;

            currentSnapshot.iX    = iX;
            currentSnapshot.iY    = iY;
            currentSnapshot.iPx   = iPx;
            currentSnapshot.iPy   = iPy;
            currentSnapshot.stage = 0;

            stack.Push(currentSnapshot);
            while (stack.Count != 0)
            {
                currentSnapshot = stack.Pop();
                switch (currentSnapshot.stage)
                {
                case 0:
                    if (!iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY))
                    {
                        retVal = null;
                        continue;
                    }
                    else if (iParam.SearchGrid.GetNodeAt(currentSnapshot.iX, currentSnapshot.iY).Equals(iParam.EndNode))
                    {
                        retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                        continue;
                    }

                    currentSnapshot.tDx = currentSnapshot.iX - currentSnapshot.iPx;
                    currentSnapshot.tDy = currentSnapshot.iY - currentSnapshot.iPy;
                    currentSnapshot.jx  = null;
                    currentSnapshot.jy  = null;
                    if (iParam.CrossCorner)
                    {
                        // check for forced neighbors
                        // along the diagonal
                        if (currentSnapshot.tDx != 0 && currentSnapshot.tDy != 0)
                        {
                            if ((iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - currentSnapshot.tDx, currentSnapshot.iY + currentSnapshot.tDy) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - currentSnapshot.tDx, currentSnapshot.iY)) ||
                                (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY - currentSnapshot.tDy) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY - currentSnapshot.tDy)))
                            {
                                retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                                continue;
                            }
                        }
                        // horizontally/vertically
                        else
                        {
                            if (currentSnapshot.tDx != 0)
                            {
                                // moving along x
                                if ((iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY + 1) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + 1)) ||
                                    (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY - 1) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY - 1)))
                                {
                                    retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                                    continue;
                                }
                            }
                            else
                            {
                                if ((iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + 1, currentSnapshot.iY + currentSnapshot.tDy) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + 1, currentSnapshot.iY)) ||
                                    (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - 1, currentSnapshot.iY + currentSnapshot.tDy) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - 1, currentSnapshot.iY)))
                                {
                                    retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                                    continue;
                                }
                            }
                        }
                        // when moving diagonally, must check for vertical/horizontal jump points
                        if (currentSnapshot.tDx != 0 && currentSnapshot.tDy != 0)
                        {
                            currentSnapshot.stage = 1;
                            stack.Push(currentSnapshot);

                            newSnapshot       = new JumpSnapshot();
                            newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                            newSnapshot.iY    = currentSnapshot.iY;
                            newSnapshot.iPx   = currentSnapshot.iX;
                            newSnapshot.iPy   = currentSnapshot.iY;
                            newSnapshot.stage = 0;
                            stack.Push(newSnapshot);
                            continue;
                        }

                        // moving diagonally, must make sure one of the vertical/horizontal
                        // neighbors is open to allow the path

                        // moving diagonally, must make sure one of the vertical/horizontal
                        // neighbors is open to allow the path
                        if (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY) || iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + currentSnapshot.tDy))
                        {
                            newSnapshot       = new JumpSnapshot();
                            newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                            newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                            newSnapshot.iPx   = currentSnapshot.iX;
                            newSnapshot.iPy   = currentSnapshot.iY;
                            newSnapshot.stage = 0;
                            stack.Push(newSnapshot);
                            continue;
                        }
                        else if (iParam.CrossAdjacentPoint)
                        {
                            newSnapshot       = new JumpSnapshot();
                            newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                            newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                            newSnapshot.iPx   = currentSnapshot.iX;
                            newSnapshot.iPy   = currentSnapshot.iY;
                            newSnapshot.stage = 0;
                            stack.Push(newSnapshot);
                            continue;
                        }
                    }
                    else     //if (!iParam.CrossCorner)
                    {
                        // check for forced neighbors
                        // along the diagonal
                        if (currentSnapshot.tDx != 0 && currentSnapshot.tDy != 0)
                        {
                            if ((iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY + currentSnapshot.tDy) && iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + currentSnapshot.tDy) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY)) ||
                                (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY + currentSnapshot.tDy) && iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + currentSnapshot.tDy)))
                            {
                                retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                                continue;
                            }
                        }
                        // horizontally/vertically
                        else
                        {
                            if (currentSnapshot.tDx != 0)
                            {
                                // moving along x
                                if ((iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + 1) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - currentSnapshot.tDx, currentSnapshot.iY + 1)) ||
                                    (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY - 1) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - currentSnapshot.tDx, currentSnapshot.iY - 1)))
                                {
                                    retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                                    continue;
                                }
                            }
                            else
                            {
                                if ((iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + 1, currentSnapshot.iY) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + 1, currentSnapshot.iY - currentSnapshot.tDy)) ||
                                    (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - 1, currentSnapshot.iY) && !iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX - 1, currentSnapshot.iY - currentSnapshot.tDy)))
                                {
                                    retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                                    continue;
                                }
                            }
                        }


                        // when moving diagonally, must check for vertical/horizontal jump points
                        if (currentSnapshot.tDx != 0 && currentSnapshot.tDy != 0)
                        {
                            currentSnapshot.stage = 3;
                            stack.Push(currentSnapshot);

                            newSnapshot       = new JumpSnapshot();
                            newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                            newSnapshot.iY    = currentSnapshot.iY;
                            newSnapshot.iPx   = currentSnapshot.iX;
                            newSnapshot.iPy   = currentSnapshot.iY;
                            newSnapshot.stage = 0;
                            stack.Push(newSnapshot);
                            continue;
                        }

                        // moving diagonally, must make sure both of the vertical/horizontal
                        // neighbors is open to allow the path
                        if (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY) && iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + currentSnapshot.tDy))
                        {
                            newSnapshot       = new JumpSnapshot();
                            newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                            newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                            newSnapshot.iPx   = currentSnapshot.iX;
                            newSnapshot.iPy   = currentSnapshot.iY;
                            newSnapshot.stage = 0;
                            stack.Push(newSnapshot);
                            continue;
                        }
                    }
                    retVal = null;
                    break;

                case 1:
                    currentSnapshot.jx = retVal;

                    currentSnapshot.stage = 2;
                    stack.Push(currentSnapshot);

                    newSnapshot       = new JumpSnapshot();
                    newSnapshot.iX    = currentSnapshot.iX;
                    newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                    newSnapshot.iPx   = currentSnapshot.iX;
                    newSnapshot.iPy   = currentSnapshot.iY;
                    newSnapshot.stage = 0;
                    stack.Push(newSnapshot);
                    break;

                case 2:
                    currentSnapshot.jy = retVal;
                    if (currentSnapshot.jx != null || currentSnapshot.jy != null)
                    {
                        retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                        continue;
                    }

                    // moving diagonally, must make sure one of the vertical/horizontal
                    // neighbors is open to allow the path
                    if (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY) || iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + currentSnapshot.tDy))
                    {
                        newSnapshot       = new JumpSnapshot();
                        newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                        newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                        newSnapshot.iPx   = currentSnapshot.iX;
                        newSnapshot.iPy   = currentSnapshot.iY;
                        newSnapshot.stage = 0;
                        stack.Push(newSnapshot);
                        continue;
                    }
                    else if (iParam.CrossAdjacentPoint)
                    {
                        newSnapshot       = new JumpSnapshot();
                        newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                        newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                        newSnapshot.iPx   = currentSnapshot.iX;
                        newSnapshot.iPy   = currentSnapshot.iY;
                        newSnapshot.stage = 0;
                        stack.Push(newSnapshot);
                        continue;
                    }
                    retVal = null;
                    break;

                case 3:
                    currentSnapshot.jx = retVal;

                    currentSnapshot.stage = 4;
                    stack.Push(currentSnapshot);

                    newSnapshot       = new JumpSnapshot();
                    newSnapshot.iX    = currentSnapshot.iX;
                    newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                    newSnapshot.iPx   = currentSnapshot.iX;
                    newSnapshot.iPy   = currentSnapshot.iY;
                    newSnapshot.stage = 0;
                    stack.Push(newSnapshot);
                    break;

                case 4:
                    currentSnapshot.jy = retVal;
                    if (currentSnapshot.jx != null || currentSnapshot.jy != null)
                    {
                        retVal = new LPoint(currentSnapshot.iX, currentSnapshot.iY);
                        continue;
                    }

                    // moving diagonally, must make sure both of the vertical/horizontal
                    // neighbors is open to allow the path
                    if (iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX + currentSnapshot.tDx, currentSnapshot.iY) && iParam.SearchGrid.IsWalkableAt(currentSnapshot.iX, currentSnapshot.iY + currentSnapshot.tDy))
                    {
                        newSnapshot       = new JumpSnapshot();
                        newSnapshot.iX    = currentSnapshot.iX + currentSnapshot.tDx;
                        newSnapshot.iY    = currentSnapshot.iY + currentSnapshot.tDy;
                        newSnapshot.iPx   = currentSnapshot.iX;
                        newSnapshot.iPy   = currentSnapshot.iY;
                        newSnapshot.stage = 0;
                        stack.Push(newSnapshot);
                        continue;
                    }
                    retVal = null;
                    break;
                }
            }

            return(retVal);
        }