How to resolve the algorithm Forest fire step by step in the C# programming language
How to resolve the algorithm Forest fire step by step in the C# programming language
Table of Contents
Problem Statement
Implement the Drossel and Schwabl definition of the forest-fire model.
It is basically a 2D cellular automaton where each cell can be in three distinct states (empty, tree and burning) and evolves according to the following rules (as given by Wikipedia) Neighborhood is the Moore neighborhood; boundary conditions are so that on the boundary the cells are always empty ("fixed" boundary condition). At the beginning, populate the lattice with empty and tree cells according to a specific probability (e.g. a cell has the probability 0.5 to be a tree). Then, let the system evolve. Task's requirements do not include graphical display or the ability to change parameters (probabilities p and f ) through a graphical or command line interface.
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Forest fire step by step in the C# programming language
This C# program simulates a forest fire using a cellular automaton model. It creates a grid of cells, representing a forest, and initializes each cell with a state of empty, tree, or burning. The fire simulation proceeds in steps, where each step involves updating the cell states based on a set of rules.
1. Initialization:
- The
InitializeForestFire
method initializes thestate
array, which represents the grid of cells, with all cells set to theEmpty
state.
2. Simulation Loop:
- The main simulation loop is in the
StepForestFire
method, which takes the current forest state as input and returns a new forest state for the next step. - For each cell in the grid (except for the border cells), the following rules are applied:
- If the cell is empty, there is a
1/p
chance it will become a tree. - If the cell is a tree and any of its neighbors are burning, it becomes burning. Otherwise, there is a
1/f
chance it will spontaneously combust and become burning. - If the cell is burning, it becomes empty.
- If the cell is empty, there is a
3. Graphical Representation:
- The program creates a graphical representation of the forest fire using a
Bitmap
andGraphics
objects. - The
OnPaint
method of theProgram
class draws the forest state onto theimg
Bitmap
, with cells colored according to their state:- Empty cells are white.
- Tree cells are dark green.
- Burning cells are dark red.
- The
Invoke
method is used to update the graphical representation from within the multi-threaded simulation.
4. Multi-Threading:
- The simulation is run in a separate thread using a
Thread
object. This allows the user to interact with the form while the simulation is running.
5. Main Function:
- The
Main
function creates an instance of theProgram
class with the specified dimensions and parameters and runs the forest fire simulation.
Additional Notes:
- The
NeighborHasState
method checks if any of a cell's neighbors has a specific state. - The
CellState
enum represents the possible states of a cell.
Source code in the csharp programming language
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Threading;
using System.Windows.Forms;
namespace ForestFire
{
class Program : Form
{
private static readonly Random rand = new Random();
private Bitmap img;
public Program(int w, int h, int f, int p)
{
Size = new Size(w, h);
StartPosition = FormStartPosition.CenterScreen;
Thread t = new Thread(() => fire(f, p));
t.Start();
FormClosing += (object sender, FormClosingEventArgs e) => { t.Abort(); t = null; };
}
private void fire(int f, int p)
{
int clientWidth = ClientRectangle.Width;
int clientHeight = ClientRectangle.Height;
int cellSize = 10;
img = new Bitmap(clientWidth, clientHeight);
Graphics g = Graphics.FromImage(img);
CellState[,] state = InitializeForestFire(clientWidth, clientHeight);
uint generation = 0;
do
{
g.FillRectangle(Brushes.White, 0, 0, img.Width, img.Height);
state = StepForestFire(state, f, p);
for (int y = 0; y < clientHeight - cellSize; y += cellSize)
{
for (int x = 0; x < clientWidth - cellSize; x += cellSize)
{
switch (state[y, x])
{
case CellState.Empty:
break;
case CellState.Tree:
g.FillRectangle(Brushes.DarkGreen, x, y, cellSize, cellSize);
break;
case CellState.Burning:
g.FillRectangle(Brushes.DarkRed, x, y, cellSize, cellSize);
break;
}
}
}
Thread.Sleep(500);
Invoke((MethodInvoker)Refresh);
} while (generation < uint.MaxValue);
g.Dispose();
}
private CellState[,] InitializeForestFire(int width, int height)
{
// Create our state array, initialize all indices as Empty, and return it.
var state = new CellState[height, width];
state.Initialize();
return state;
}
private enum CellState : byte
{
Empty = 0,
Tree = 1,
Burning = 2
}
private CellState[,] StepForestFire(CellState[,] state, int f, int p)
{
/* Clone our old state, so we can write to our new state
* without changing any values in the old state. */
var newState = (CellState[,])state.Clone();
int numRows = state.GetLength(0);
int numCols = state.GetLength(1);
for (int r = 1; r < numRows - 1; r++)
{
for (int c = 1; c < numCols - 1; c++)
{
/*
* Check the current cell.
*
* If it's empty, give it a 1/p chance of becoming a tree.
*
* If it's a tree, check to see if any neighbors are burning.
* If so, set the cell's state to burning, otherwise give it
* a 1/f chance of combusting.
*
* If it's burning, set it to empty.
*/
switch (state[r, c])
{
case CellState.Empty:
if (rand.Next(0, p) == 0)
newState[r, c] = CellState.Tree;
break;
case CellState.Tree:
if (NeighborHasState(state, r, c, CellState.Burning) || rand.Next(0, f) == 0)
newState[r, c] = CellState.Burning;
break;
case CellState.Burning:
newState[r, c] = CellState.Empty;
break;
}
}
}
return newState;
}
private bool NeighborHasState(CellState[,] state, int x, int y, CellState value)
{
// Check each cell within a 1 cell radius for the specified value.
for (int r = -1; r <= 1; r++)
{
for (int c = -1; c <= 1; c++)
{
if (r == 0 && c == 0)
continue;
if (state[x + r, y + c] == value)
return true;
}
}
return false;
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
e.Graphics.DrawImage(img, 0, 0);
}
[STAThread]
static void Main(string[] args)
{
Application.Run(new Program(w: 500, h: 500, f: 2, p: 5));
}
}
}
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