/**
* 判断能否从当前cell走到下一个cell
* @param startCell
* @param nextCell
* @return
*/
private bool canWalkToNextCell(Point startCell, Point nextCell)
{
// 下一个点在阻挡区域，直接不可达
if (AStarCell.isObstacle(map.getCell(nextCell.x, nextCell.y)))
{
return(false);
}
// 下一个cell是前一个cell的上下左右的cell，可达
if (startCell.x == nextCell.x || startCell.y == nextCell.y)
{
return(true);
}
// 否则是对角cell，判断法向对角的两个cell是否都在阻挡区域，如果是则不可达
if (AStarCell.isObstacle(map.getCell(startCell.x, nextCell.y)) &&
AStarCell.isObstacle(map.getCell(nextCell.x, startCell.y)))
{
return(false);
}
else
{
return(true);
}
}
/**
* Bresenham line algorithm
* @param start
* @param goal
* @return
*/
public Point raycast(Vector2 startPos, Vector2 goalPos, float cellSize)
{
Point startCell = posToCell(startPos, cellSize);
Point goalCell = posToCell(goalPos, cellSize);
// exception: start is obstacle. Now just return start
if (AStarCell.isObstacle(map.getCell(startCell.x, startCell.y)))
{
return(startCell);
}
if (startCell.Equals(goalCell))
{
return(startCell);
}
float diffx = goalPos.x - startPos.x;
float diffy = goalPos.y - startPos.y;
float distanceSquare = diffx * diffx + diffy * diffy;
float distance = (float)Math.Sqrt(distanceSquare);
Vector2 dir = new Vector2(diffx / distance, diffy / distance);
Vector2 lastPassed = startPos;
Point hitPoint = new Point(startCell.x, startCell.y);
while (true)
{
Vector2 nextPos = getNextPos(lastPassed, dir, cellSize);
Point newCell = posToCell(nextPos, cellSize);
float dis = (nextPos.x - startPos.x) * (nextPos.x - startPos.x) + (nextPos.y - startPos.y) * (nextPos.y - startPos.y);
if (dis >= distanceSquare)
{
break;
}
if (!canWalkToNextCell(hitPoint, newCell))
{
break;
}
else
{
hitPoint.x = newCell.x;
hitPoint.y = newCell.y;
if (newCell.Equals(goalCell))
{
break;
}
}
lastPassed = nextPos;
}
return(hitPoint);
}
public PrintMap(AStarMap map, List <Point> shortestPath)
{
StringBuilder sb = new StringBuilder();
AStarCell cell;
for (int y = 0; y < map.getHeightInCells(); y++)
{
if (y == 0)
{
for (int i = 0; i <= map.getHeightInCells(); i++)
{
sb.Append("-");
}
sb.AppendLine();
}
sb.Append("|");
for (int x = 0; x < map.getWidthInCells(); x++)
{
cell = map.getCell(x, y);
if (AStarCell.isObstacle(cell))
{
sb.Append("X");
}
else if (isStart(shortestPath, cell.getPoint()))
{
sb.Append("s");
}
else if (isGoal(shortestPath, cell.getPoint()))
{
sb.Append("g");
}
else if (contains(shortestPath, cell.getPoint()))
{
sb.Append("?");
}
else
{
sb.Append(" ");
}
if (y == map.getHeightInCells())
{
sb.Append("_");
}
}
sb.Append("|");
sb.AppendLine();
}
for (int i = 0; i <= map.getHeightInCells(); i++)
{
sb.Append("-");
}
//System.Console.SetWindowSize(System.Console.LargestWindowWidth, System.Console.LargestWindowHeight);
//System.Console.Write(sb.ToString());
}
private bool lineClear(Point a, Point b)
{
List <Point> pointsOnLine = Bresenham.getCellsOnLine(a, b);
foreach (Point p in pointsOnLine)
{
AStarCell cell = map.getCell(p.x, p.y);
if (cell == null || cell.isObstacle())
{
return(false);
}
}
return(true);
}
public Point raycast(Point start, Point goal)
{
List <Point> pointsOnLine = Bresenham.getCellsOnLine(start, goal);
Point hitPoint = (Point)start.Clone();
foreach (Point p in pointsOnLine)
{
AStarCell cell = map.getCell(p.x, p.y);
if (cell == null || cell.isObstacle())
{
break;
}
else
{
hitPoint = p;
}
}
return(hitPoint);
}
public Vector2 Raycast(Vector2 startPos, Vector2 endPos)
{
Point startCell = PathFinder.posToCell(startPos, astarMap.getCellSize());
Point goalCell = PathFinder.posToCell(endPos, astarMap.getCellSize());
// exception: start is obstacle. Now just return start
if (AStarCell.isObstacle(astarMap.getCell(startCell.x, startCell.y)))
{
return(startPos);
}
if (startCell.Equals(goalCell))
{
return(endPos);
}
Point hitCell = pathFinder.raycast(startPos, endPos, astarMap.getCellSize());
Vector2 hitPos = PathFinder.cellToPos(hitCell, astarMap.getCellSize());
Vector2 dir = (endPos - startPos).normalized;
hitPos = PathFinder.getNextPosBeforeNextCell(hitPos, dir, astarMap.getCellSize());
return(hitPos);
}
public Point getCellWithErrorTolerate(float x, float y)
{
int cellX = (int)Math.Floor((x + map.getErrorTolerate()) / map.getCellSize());
int cellY = (int)Math.Floor((y + map.getErrorTolerate()) / map.getCellSize());
AStarCell cell = map.getCell(cellX, cellY);
if (!AStarCell.isObstacle(cell))
{
return(new Point(cellX, cellY));
}
cellX = (int)Math.Floor((x - map.getErrorTolerate()) / map.getCellSize());
cellY = (int)Math.Floor((y - map.getErrorTolerate()) / map.getCellSize());
cell = map.getCell(cellX, cellY);
if (!AStarCell.isObstacle(cell))
{
return(new Point(cellX, cellY));
}
cellX = (int)Math.Floor((x + map.getErrorTolerate()) / map.getCellSize());
cellY = (int)Math.Floor((y - map.getErrorTolerate()) / map.getCellSize());
cell = map.getCell(cellX, cellY);
if (!AStarCell.isObstacle(cell))
{
return(new Point(cellX, cellY));
}
cellX = (int)Math.Floor((x - map.getErrorTolerate()) / map.getCellSize());
cellY = (int)Math.Floor((y + map.getErrorTolerate()) / map.getCellSize());
cell = map.getCell(cellX, cellY);
if (!AStarCell.isObstacle(cell))
{
return(new Point(cellX, cellY));
}
return(null);
}