Monkey-X - Diffusion Limited Aggregation - Map Generator - code example

'diffusion limited aggregation (dla)

' This basically works like this.
' You create random walkers(dots) They move into a random direction.
' On the map there is a solid part and if the walker touches it he turns
' into a solid part. This is it.


Import mojo

' The random walker class. We only use it to store
' the x and y coordinates
Class walker
    Field x:Int,y:Int
    Field deleteme:Bool
    Method New(x:Int,y:Int)
        Self.x = x
        Self.y = y
    End Method
End Class

Class dla
    ' map width/height screen width/height
    ' tile width/height
    ' map containing the solids parts. 
    ' The walker list containing the walkers
    Field mw:Int,mh:Int,sw:Int,sh:Int
    Field tw:Float,th:Float
    Field map:Int[][]
    Field mywalker:List<walker>
    Field walkerradius:Int=1
    Field finished:Bool=False
    Method New(sw:Int,sh:Int,mw:Int,mh:Int)
        Self.sw = sw
        Self.sh = sh
        Self.mw = mw
        Self.mh = mh
        Self.tw = Float(sw) / Float(mw)
        Self.th = Float(sh) / Float(mh)
        ' create our map array
        map = New Int[mw][]
        For Local i:=0 Until mw
            map[i] = New Int[mh]
        Next
        ' create the solid part
        mapcircle(mw/2,mh/2)
        ' create the walker list
        mywalker = New List<walker>
        'add some walkers to the list
        For Local i:=0 Until mw*mh/20
            addwalker(Rnd(4))
        Next
    End Method    
    ' Here we update the walkers. We keep adding them to 
    ' the screen until they have created a solid part 
    ' on the most part of the screen.
    Method update()
        ' speed it up    
        For Local speed:Int=0 Until 20
            ' loop through each walker on the list
            For Local i:=Eachin mywalker
                ' step in one of 8 directions    
                Local x:Int=Rnd(-2,2)
                Local y:Int=Rnd(-2,2)
                ' if we are not moving outside of the map 
                ' then update position
                If i.x+x >= 0 And i.x+x < mw Then i.x += x
                If i.y+y >= 0 And i.y+y < mh Then i.y += y
                ' if we touch a solid then
                If map[i.x][i.y] = 1 Then
                    ' flag for deletion
                    i.deleteme = True
                    ' if the last position was not near the edge of the screen
                    If i.x > 10 And i.x < mw-10 And i.y > 10 And i.y < mh-10
                        ' add new walker to the border of screen
                        addwalker(Rnd(4))
                    End If
                    ' Draw the new solid
                    mapcircle(i.x,i.y)
                End If
            Next
            ' Go through the walker list and see if
            ' we can delete any walkers from the list
            For Local i:=Eachin mywalker
                If i.deleteme = True Then mywalker.Remove(i)
            Next
        Next
        If mywalker.IsEmpty Then finished = True
    End Method
    ' Add a walker to the list at a random edge location
    Method addwalker(loc:Int)
        Select loc
            Case 0'top
                mywalker.AddLast(New walker(Rnd(mw),0))
            Case 1'bottom
                mywalker.AddLast(New walker(Rnd(mw),mh-1))
            Case 2'left
                mywalker.AddLast(New walker(0,Rnd(mh)))
            Case 3'"right"
                mywalker.AddLast(New walker(mw-1,Rnd(mh)))
        End Select
    End Method
    Method mapcircle(x:Int,y:Int)
        For Local y2:=-walkerradius To walkerradius
        For Local x2:=-walkerradius To walkerradius
            Local x3:Int=x+x2
            Local y3:Int=y+y2
            If x3<0 Or y3<0 Or x3>=mw Or y3>=mh Then Continue
            map[x3][y3] = 1
        Next
        Next
    End Method
    ' Draw the solid and walkers
    Method draw()
        For Local y:=0 Until mh
        For Local x:=0 Until mw
            If map[x][y] = 1 Then
                SetColor 255,255,255
                DrawRect x*tw,y*th,tw+1,th+1
            End If
        Next
        Next
        For Local i:=Eachin mywalker
            DrawCircle i.x*tw,i.y*th,walkerradius*th
        Next
        
    End Method
End Class

Class MyGame Extends App
    Field mydla:dla
    Field count:Int=200
    Method OnCreate()
        SetUpdateRate(60)
        Seed = GetDate[4] + GetDate[5]
        mydla = New dla(DeviceWidth(),DeviceHeight(),100,100)
    End Method
    Method OnUpdate()
        mydla.update()        
        If MouseHit(MOUSE_LEFT) Then mydla.finished = True ; count=0
        If mydla.finished = True Then
            count-=1
            If count<0 
            Local s:Int=Rnd(50,256)
            mydla = New dla(DeviceWidth(),DeviceHeight(),s,s)
            count=200
            End If
        End If
    End Method
    Method OnRender()
        Cls 0,0,0 
        mydla.draw()
        SetColor 255,255,255
        DrawText "Diffusion Limited Aggregation map generator - click = new",0,0
    End Method
End Class


Function Main()
    New MyGame()
End Function