Task: Forest fire








VB: Public Class ForestFire
    Private _forest(,) As ForestState
    Private _isBuilding As Boolean
    Private _bm As Bitmap
    Private _gen As Integer
    Private _sw As Stopwatch

    Private Const _treeStart As Double = 0.5
    Private Const _f As Double = 0.00001
    Private Const _p As Double = 0.001

    Private Const _winWidth As Integer = 300
    Private Const _winHeight As Integer = 300

    Private Enum ForestState
        Empty
        Burning
        Tree
    End Enum

    Private Sub ForestFire_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.ClientSize = New Size(_winWidth, _winHeight)
        ReDim _forest(_winWidth, _winHeight)

        Dim rnd As New Random()
        For i As Integer = 0 To _winHeight - 1
            For j As Integer = 0 To _winWidth - 1
                _forest(j, i) = IIf(rnd.NextDouble <= _treeStart, ForestState.Tree, ForestState.Empty)
            Next
        Next

        _sw = New Stopwatch
        _sw.Start()
        DrawForest()
        Timer1.Start()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If _isBuilding Then Exit Sub

        _isBuilding = True
        GetNextGeneration()

        DrawForest()
        _isBuilding = False
    End Sub

    Private Sub GetNextGeneration()
        Dim forestCache(_winWidth, _winHeight) As ForestState
        Dim rnd As New Random()

        For i As Integer = 0 To _winHeight - 1
            For j As Integer = 0 To _winWidth - 1
                Select Case _forest(j, i)
                    Case ForestState.Tree
                        If forestCache(j, i) <> ForestState.Burning Then
                            forestCache(j, i) = IIf(rnd.NextDouble <= _f, ForestState.Burning, ForestState.Tree)
                        End If

                    Case ForestState.Burning
                        For i2 As Integer = i - 1 To i + 1
                            If i2 = -1 OrElse i2 >= _winHeight Then Continue For
                            For j2 As Integer = j - 1 To j + 1
                                If j2 = -1 OrElse i2 >= _winWidth Then Continue For
                                If _forest(j2, i2) = ForestState.Tree Then forestCache(j2, i2) = ForestState.Burning
                            Next
                        Next
                        forestCache(j, i) = ForestState.Empty

                    Case Else
                        forestCache(j, i) = IIf(rnd.NextDouble <= _p, ForestState.Tree, ForestState.Empty)
                End Select
            Next
        Next

        _forest = forestCache
        _gen += 1
    End Sub

    Private Sub DrawForest()
        Dim bmCache As New Bitmap(_winWidth, _winHeight)

        For i As Integer = 0 To _winHeight - 1
            For j As Integer = 0 To _winWidth - 1
                Select Case _forest(j, i)
                    Case ForestState.Tree
                        bmCache.SetPixel(j, i, Color.Green)

                    Case ForestState.Burning
                        bmCache.SetPixel(j, i, Color.Red)
                End Select
            Next
        Next

        _bm = bmCache
        Me.Refresh()
    End Sub

    Private Sub ForestFire_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
        e.Graphics.DrawImage(_bm, 0, 0)

        Me.Text = "Gen " & _gen.ToString() & " @ " & (_gen / (_sw.ElapsedMilliseconds / 1000)).ToString("F02") & " FPS: Forest Fire"
    End Sub
End Class




Ada: with Ada.Numerics.Float_Random;  use Ada.Numerics.Float_Random;
with Ada.Text_IO;                use Ada.Text_IO;

procedure Forest_Fire is
   type Cell is (Empty, Tree, Fire);
   type Board is array (Positive range <>, Positive range <>) of Cell;
   procedure Step (S : in out Board; P, F : Float; Dice : Generator) is
      function "+" (Left : Boolean; Right : Cell) return Boolean is
      begin
         return Left or else Right = Fire;
      end "+";
      function "+" (Left, Right : Cell) return Boolean is
      begin
         return Left = Fire or else Right = Fire;
      end "+";
      Above : array (S'Range (2)) of Cell := (others => Empty);
      Left_Up, Up, Left : Cell;
   begin
      for Row in S'First (1) + 1..S'Last (1) - 1 loop
         Left_Up := Empty;
         Up      := Empty;
         Left    := Empty;
         for Column in S'First (2) + 1..S'Last (2) - 1 loop
            Left_Up := Up;
            Up      := Above (Column);
            Above (Column) := S (Row, Column);
            case S (Row, Column) is
               when Empty =>
                  if Random (Dice) < P then
                     S (Row, Column) := Tree;
                  end if;
               when Tree =>
                  if Left_Up                 + Up                  +      Above (Column + 1) +
                     Left                    + S (Row,     Column) + S (Row,     Column + 1) +
                     S (Row + 1, Column - 1) + S (Row + 1, Column) + S (Row + 1, Column + 1)
                  or else Random (Dice) < F then
                     S (Row, Column) := Fire;
                  end if;
               when Fire =>
                  S (Row, Column) := Empty;
            end case;
            Left := Above (Column);
         end loop;
      end loop;
   end Step;
   procedure Put (S : Board) is
   begin
      for Row in S'First (1) + 1..S'Last (1) - 1 loop
         for Column in S'First (2) + 1..S'Last (2) - 1 loop
            case S (Row, Column) is
               when Empty => Put (' ');
               when Tree  => Put ('Y');
               when Fire  => Put ('#');
            end case;
         end loop;
         New_Line;
      end loop;      
   end Put;
   
   Dice   : Generator;
   Forest : Board := (1..10 => (1..40 => Empty));
begin
   Reset (Dice);
   for I in 1..10 loop
      Step (Forest, 0.3, 0.1, Dice);
      Put_Line ("
      Put (Forest);
   end loop;
end Forest_Fire;