ModernUO/Projects/Scripts/Engines/Pathing/SlowAStarAlgorithm.cs

using System;
using Server.Mobiles;

namespace Server.PathAlgorithms
{
  public class SlowAStarAlgorithm : PathAlgorithm
  {
    public struct PathNode
    {
      public int x, y, z;
      public int g, h;
      public int px, py, pz;
      public int dir;
    }

    private const int MaxDepth = 300;
    private const int MaxNodes = MaxDepth * 16;
    public static PathAlgorithm Instance = new SlowAStarAlgorithm();

    private static PathNode[] m_Closed = new PathNode[MaxNodes];
    private static PathNode[] m_Open = new PathNode[MaxNodes];
    private static PathNode[] m_Successors = new PathNode[8];
    private static Direction[] m_Path = new Direction[MaxNodes];

    private Point3D m_Goal;

    public int Heuristic(int x, int y, int z)
    {
      x -= m_Goal.X;
      y -= m_Goal.Y;
      z -= m_Goal.Z;

      x *= 11;
      y *= 11;

      return x * x + y * y + z * z;
    }

    public override bool CheckCondition(Mobile m, Map map, Point3D start, Point3D goal) => false;

    public override Direction[] Find(Mobile m, Map map, Point3D start, Point3D goal)
    {
      m_Goal = goal;

      BaseCreature bc = m as BaseCreature;

      PathNode curNode;

      PathNode goalNode = new PathNode();
      goalNode.x = goal.X;
      goalNode.y = goal.Y;
      goalNode.z = goal.Z;

      PathNode startNode = new PathNode();
      startNode.x = start.X;
      startNode.y = start.Y;
      startNode.z = start.Z;
      startNode.h = Heuristic(startNode.x, startNode.y, startNode.z);

      PathNode[] closed = m_Closed, open = m_Open, successors = m_Successors;
      Direction[] path = m_Path;

      int closedCount = 0, openCount = 0;
      int pathCount = 0;
      int depth = 0;

      int iBacktrack = 0;

      open[openCount++] = startNode;

      while (openCount > 0)
      {
        curNode = open[0];
        int curF = curNode.g + curNode.h;
        int popIndex = 0;

        for (int i = 1; i < openCount; ++i)
          if (open[i].g + open[i].h < curF)
          {
            curNode = open[i];
            curF = curNode.g + curNode.h;
            popIndex = i;
          }

        if (curNode.x == goalNode.x && curNode.y == goalNode.y && Math.Abs(curNode.z - goalNode.z) < 16)
        {
          if (closedCount == MaxNodes)
            break;

          closed[closedCount++] = curNode;

          int xBacktrack = curNode.px;
          int yBacktrack = curNode.py;
          int zBacktrack = curNode.pz;

          if (pathCount == MaxNodes)
            break;

          path[pathCount++] = (Direction)curNode.dir;

          while (xBacktrack != startNode.x || yBacktrack != startNode.y || zBacktrack != startNode.z)
          {
            bool found = false;

            for (int j = 0; !found && j < closedCount; ++j)
              if (closed[j].x == xBacktrack && closed[j].y == yBacktrack && closed[j].z == zBacktrack)
              {
                if (pathCount == MaxNodes)
                  break;

                curNode = closed[j];
                path[pathCount++] = (Direction)curNode.dir;
                xBacktrack = curNode.px;
                yBacktrack = curNode.py;
                zBacktrack = curNode.pz;
                found = true;
              }

            if (!found)
            {
              Console.WriteLine("bugaboo..");
              return null;
            }

            if (pathCount == MaxNodes)
              break;
          }

          if (pathCount == MaxNodes)
            break;

          Direction[] dirs = new Direction[pathCount];

          while (pathCount > 0)
            dirs[iBacktrack++] = path[--pathCount];

          return dirs;
        }

        --openCount;

        for (int i = popIndex; i < openCount; ++i)
          open[i] = open[i + 1];

        int sucCount = 0;

        if (bc != null)
        {
          MovementImpl.AlwaysIgnoreDoors = bc.CanOpenDoors;
          MovementImpl.IgnoreMovableImpassables = bc.CanMoveOverObstacles;
        }

        MovementImpl.Goal = goal;

        int x;
        int y;
        int z;
        for (int i = 0; i < 8; ++i)
        {
          switch (i)
          {
            default:
              x = 0;
              y = -1;
              break;
            case 1:
              x = 1;
              y = -1;
              break;
            case 2:
              x = 1;
              y = 0;
              break;
            case 3:
              x = 1;
              y = 1;
              break;
            case 4:
              x = 0;
              y = 1;
              break;
            case 5:
              x = -1;
              y = 1;
              break;
            case 6:
              x = -1;
              y = 0;
              break;
            case 7:
              x = -1;
              y = -1;
              break;
          }

          if (Movement.CheckMovement(m, map, new Point3D(curNode.x, curNode.y, curNode.z), (Direction)i, out z))
          {
            successors[sucCount].x = x + curNode.x;
            successors[sucCount].y = y + curNode.y;
            successors[sucCount++].z = z;
          }
        }

        MovementImpl.AlwaysIgnoreDoors = false;
        MovementImpl.IgnoreMovableImpassables = false;
        MovementImpl.Goal = Point3D.Zero;

        if (sucCount == 0 || ++depth > MaxDepth)
          break;

        for (int i = 0; i < sucCount; ++i)
        {
          x = successors[i].x;
          y = successors[i].y;
          z = successors[i].z;

          successors[i].g = curNode.g + 1;

          int openIndex = -1, closedIndex = -1;

          for (int j = 0; openIndex == -1 && j < openCount; ++j)
            if (open[j].x == x && open[j].y == y && open[j].z == z)
              openIndex = j;

          if (openIndex >= 0 && open[openIndex].g < successors[i].g)
            continue;

          for (int j = 0; closedIndex == -1 && j < closedCount; ++j)
            if (closed[j].x == x && closed[j].y == y && closed[j].z == z)
              closedIndex = j;

          if (closedIndex >= 0 && closed[closedIndex].g < successors[i].g)
            continue;

          if (openIndex >= 0)
          {
            --openCount;

            for (int j = openIndex; j < openCount; ++j)
              open[j] = open[j + 1];
          }

          if (closedIndex >= 0)
          {
            --closedCount;

            for (int j = closedIndex; j < closedCount; ++j)
              closed[j] = closed[j + 1];
          }

          successors[i].px = curNode.x;
          successors[i].py = curNode.y;
          successors[i].pz = curNode.z;
          successors[i].dir = (int)GetDirection(curNode.x, curNode.y, x, y);
          successors[i].h = Heuristic(x, y, z);

          if (openCount == MaxNodes)
            break;

          open[openCount++] = successors[i];
        }

        if (openCount == MaxNodes || closedCount == MaxNodes)
          break;

        closed[closedCount++] = curNode;
      }

      return null;
    }
  }
}