Thursday, April 13, 2017

Monkey-X - Maze - Randomized Kruskals Algorithm - code example

Randomized Kruskal's Algorithm - Maze

From the book - Mazes for programmers -


Import mojo

Class cell
    Field x:Int,y:Int
    Field north:Bool,east:Bool
    Field south:Bool,west:Bool
    Field visited:Bool=False
    Field value:Int
    Method New(x:Int,y:Int)
        Self.x = x
        Self.y = y
    End Method
End Class

Class randomizedkruskalsmaze
    Field width:Int,height:Int
    Field tilewidth:Float,tileheight:Float
    Field map:cell[][]
    Method New(mazewidth:Int,mazeheight:Int,sw:Int,sh:Int)
        Self.width = mazewidth
        Self.height = mazeheight
        map = New cell[width][]
        For Local i=0 Until width
            map[i] = New cell[height]
        For Local y=0 Until height
        For Local x=0 Until width
            map[x][y] = New cell
        tilewidth = Float(sw)/Float(mazewidth)
        tileheight = Float(sh)/Float(mazeheight)
    End Method
    ' This method creates the maze
    ' Randomized kruskal works by creating a stack list
    ' with connections between each cell. Either a east or
    ' a south. On the map each cell has a unique value.
    ' we randomly pick a connection from the list and connect it
    ' if the map values are different. We then turn both the
    ' different map values and turn them into one value.
    ' We then delete this connection from the list. The maze 
    ' is done if the list is empty.
    Method randomizedkruskalsmaze()
        ' create a stack list with cell class
        Local connection:Stack<cell> = New Stack<cell>
        ' variable with value to assign to each cell
        Local val:Int=0
        ' loop though the map
        For Local y=0 Until height
        For Local x=0 Until width
            ' add east link to connection stack
            If x<width-1
                connection.Push(New cell(x,y))
                connection.Top.east = True
            End If
            ' add south link to connection stack
            If y<height-1
                connection.Push(New cell(x,y))
                connection.Top.south = True            
            End If
            ' give the map its unique value
            map[x][y].value = val
            ' increase the value
        ' loop until the connection stack is empty
        While connection.IsEmpty = False
            ' get a random link from the stack
            Local r:Int = Rnd(connection.Length)
            ' get its x and y and value
            Local x:Int = connection.Get(r).x
            Local y:Int = connection.Get(r).y
            Local v:Int = map[x][y].value
            ' s we use to see if it is east or south
            Local s:Int
            If connection.Get(r).east = True Then s = 0
            If connection.Get(r).south = True Then s = 1
            ' remove the link from the stack list
            ' here we carve a connection if the cell
            ' we are on and the east or south has a different
            ' value. Then we give them one and the same value.
            Select s
                Case 0 'east
                If map[x][y].value <> map[x+1][y].value
                    map[x][y].east = True
                    map[x+1][y].west = True
                End If
                Case 1'south
                If map[x][y].value <> map[x][y+1].value
                    map[x][y].south = True
                    map[x][y+1].north = True
                End If
            End Select
    End Method
    ' This method takes all of one value on the map and turns it into 
    ' another.
    Method merge(a:Int,b:Int)
        For Local y=0 Until height
        For Local x=0 Until width
            If map[x][y].value = b Then map[x][y].value = a
    End Method
    ' Draw the maze
    Method draw()
        For Local y=0 Until height
        For Local x=0 Until width
            Local x1:Int=x*tilewidth
            Local y1:Int=y*tileheight
            SetColor 255,255,255
            If map[x][y].north = False
                DrawLine x1,y1,x1+tilewidth,y1
            End If
            If map[x][y].east = False
                DrawLine x1+tilewidth,y1,x1+tilewidth,y1+tileheight
            End If
            If map[x][y].south = False
                DrawLine x1,y1+tileheight,x1+tilewidth,y1+tileheight
            End If
            If map[x][y].west = False
                DrawLine x1,y1,x1,y1+tileheight
            End If
    End Method
End Class

Global maze:randomizedkruskalsmaze

Class MyGame Extends App
    Method OnCreate()
        maze = New randomizedkruskalsmaze(10,10,500,400)
    End Method
    Method OnUpdate()        
        If MouseHit(MOUSE_LEFT)
            maze = New randomizedkruskalsmaze(10,10,500,400)
        End If
    End Method
    Method OnRender()
        Cls 0,0,0 
        SetColor 255,255,255
        DrawText "Randomized Kruskal's Algorithm Maze",0,480-40
        DrawText "Press Mouse or Touch to create new maze",0,480-20
    End Method
End Class

Function Main()
    New MyGame()
End Function

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