//function called to find path, give start and end position of path to be found
void FindPath(TileVec2 StartPos, TileVec2 EndPos)
{
List <TileVec2> openSet = new List <TileVec2>(); //all possible positions worth searching.
HashSet <TileVec2> closedSet = new HashSet <TileVec2>(); //closed set of evaluated and discarded positions
openSet.Add(startPos); //add start pos as first tile in open set
//whilst we still have values in openset
while (openSet.Count > 0)
{
TileVec2 currentTile = openSet[0];
for (int i = 0; i < openSet.Count; i++)
{
if (openSet[i].fCost < currentTile.fCost || openSet[i].fCost == currentTile.fCost && openSet[i].hCost < currentTile.hCost)
{
currentTile = openSet[i]; //current tile is equal to next best candidate in list
}
}
openSet.Remove(currentTile); //remove tile we currently evaluating
closedSet.Add(currentTile); //move it to closed set
//if we at end position
if (currentTile.xPos == EndPos.xPos)
{
if (currentTile.yPos == EndPos.yPos)
{
//go draw path to show user
RetracePath(startPos, currentTile);
return;
}
}
//go look at our neighbours and calculate their costs and add to open list.
foreach (TileVec2 neighbour in MazeGrid.GetNeighbours(currentTile))
{
//unless they out bounds or already in closed list
if (!neighbour.isFloor || closedSet.Contains(neighbour))
{
continue;
}
int newMovCostToNeighbour = currentTile.gCost + GetDistance(currentTile, neighbour);
if (newMovCostToNeighbour < neighbour.gCost || !openSet.Contains(neighbour))
{
neighbour.gCost = newMovCostToNeighbour;
neighbour.hCost = GetDistance(neighbour, EndPos);
neighbour.parent = currentTile;
if (!openSet.Contains(neighbour))
{
openSet.Add(neighbour);
}
}
}
}
}
//retrace path
//keep looking at next tiles parent until we back at start tile
//along the way instaniate a tile to show user calculated path
void RetracePath(TileVec2 startNode, TileVec2 currentTile)
{
resetPathHolder();
while (currentTile != startNode)
{
GameObject tile = Instantiate(pathTile, new Vector3(currentTile.xPos, 0.05f, currentTile.yPos), flatTile) as GameObject;
tile.transform.parent = pathHolder.transform;
currentTile = currentTile.parent;
}
}
//function used to calculate distance between tiles
//we use a value of 10 from tile to tile vertically and horizontally, then a value of 14 fo diagonal movements due to pythagoras 1^2 + 1^2 = sqrt(2) or 1.4ish
//but use ints and scale to 10 and 14, as ints cheaper then floats
int GetDistance(TileVec2 tileA, TileVec2 tileB)
{
int xDist = Mathf.Abs(tileA.xPos - tileB.xPos);
int yDist = Mathf.Abs(tileA.yPos - tileB.yPos);
if (xDist > yDist)
{
return(14 * yDist + 10 * (xDist - yDist));
}
return(14 * xDist + 10 * (yDist - xDist));
}
//void OnDrawGizmos()
//{
// Gizmos.DrawWireCube(transform.position, new Vector3(columns, 1, rows));
//
// if (MazeGrid != null)
// {
// foreach (TileVec2 n in MazeGrid)
// {
// Gizmos.color = (n.isFloor) ? Color.white : Color.red;
// Vector3 worldPos = new Vector3(n.xPos, 0, n.yPos);
// Gizmos.DrawCube(worldPos, Vector3.one * 0.5f);
// }
// }
//
//}
//this will be used for pathfinding
void CreateGrid()
{
MazeGrid = new TileVec2[columns, rows];
for (int x = 0; x < columns; x++)
{
for (int y = 0; y < rows; y++)
{
//check each pos in maze
bool floor = FloorTiles[x, y];
//set grid to position and see if floor tile there
MazeGrid[x, y] = new TileVec2(floor, x, y);
}
}
}
void setStartEndTiles(bool start)
{
//do a raycast to see where user clicked on screen and if it hit a tile store position and place start/end tile at that positiom
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
RaycastHit hit;
if (Physics.Raycast(ray, out hit))
{
//if left click to place start tile
if (start)
{
GameObject tile = Instantiate(startTile, hit.transform.position + aboveMaze, flatTile) as GameObject;
tile.transform.parent = pathHolder.transform;
tile.name = "startTile";
//set our starttile boolean to true so we know we have a start tile in the world
blnStartTile = true;
startPos = new TileVec2(true, (int)hit.transform.position.x, (int)hit.transform.position.z);
}
//if right click to place end tile
else
{
//if start tile exists, go to place the end tile
if (blnStartTile)
{
GameObject tile = Instantiate(endTile, hit.transform.position + aboveMaze, flatTile) as GameObject;
tile.name = "endTile";
tile.transform.parent = pathHolder.transform;
//set our endtile boolean to true so we know we have a end tile in the world
//blnEndTile = true;
TileVec2 endPos = new TileVec2(true, (int)hit.transform.position.x, (int)hit.transform.position.z);
//now we have a start/end tile, go find path between them
FindPath(startPos, endPos);
}
}
}
}
//check all tiles around given tile
public List <TileVec2> GetNeighbours(TileVec2 Tile)
{
List <TileVec2> neighbours = new List <TileVec2>();
for (int x = -1; x <= 1; x++)
{
for (int y = -1; y <= 1; y++)
{
if (x == 0 && y == 0)
{
continue; //dont check self
}
int xCheck = Tile.xPos + x;
int yCheck = Tile.yPos + y;
//check we not out of bounds of grid
if (xCheck >= 0 && xCheck < columns && yCheck >= 0 && yCheck < rows)
{
neighbours.Add(MazeGrid[xCheck, yCheck]);
}
}
}
return(neighbours);
}
