using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using MLEM.Extensions; using MLEM.Input; using MLEM.Pathfinding; using MLEM.Startup; using MonoGame.Extended; namespace Demos { public class PathfindingDemo : Demo { private bool[,] world; private AStar2 pathfinder; private List path; public PathfindingDemo(MlemGame game) : base(game) { } private void Init() { // generate a simple random world for testing, where true is walkable area, and false is a wall var random = new Random(); this.world = new bool[50, 50]; for (var x = 0; x < 50; x++) { for (var y = 0; y < 50; y++) { if (random.NextDouble() >= 0.25) this.world[x, y] = true; } } // Create a cost function, which determines how expensive (or difficult) it should be to move from a given position // to the next, adjacent position. In our case, the only restriction should be walls and out-of-bounds positions, which // both have a cost of float.MaxValue, meaning they are completely unwalkable. // If your game contains harder-to-move-on areas like, say, a muddy pit, you can return a higher cost value for those // locations. If you want to scale your cost function differently, you can specify a different default cost in your // pathfinder's constructor AStar.GetCost cost = (pos, nextPos) => { if (nextPos.X < 0 || nextPos.Y < 0 || nextPos.X >= 50 || nextPos.Y >= 50) return float.MaxValue; return this.world[nextPos.X, nextPos.Y] ? 1 : float.MaxValue; }; // Actually initialize the pathfinder with the cost function, as well as specify if moving diagonally between tiles should be // allowed or not (in this case it's not) this.pathfinder = new AStar2(cost, false); // Now find a path from the top left to the bottom right corner and store it in a variable // If no path can be found after the maximum amount of tries (10000 by default), the pathfinder will abort and return no path (null) var foundPath = this.pathfinder.FindPath(Point.Zero, new Point(49, 49)); this.path = foundPath != null ? foundPath.ToList() : null; // print out some info Console.WriteLine("Pathfinding took " + this.pathfinder.LastTriesNeeded + " tries and "+this.pathfinder.LastTimeNeeded.TotalSeconds+" seconds"); if (this.path == null) Console.WriteLine("Couldn't find a path, press the left mouse button to try again"); } public override void LoadContent() { base.LoadContent(); this.Init(); } public override void Update(GameTime gameTime) { base.Update(gameTime); // when pressing the left mouse button, generate a new world and find a new path if (this.InputHandler.IsMouseButtonPressed(MouseButton.Left)) { this.Init(); } } public override void DoDraw(GameTime gameTime) { this.GraphicsDevice.Clear(Color.White); this.SpriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.PointClamp, transformMatrix: Matrix.CreateScale(14)); // draw the world with simple shapes for (var x = 0; x < 50; x++) { for (var y = 0; y < 50; y++) { if (!this.world[x, y]) { this.SpriteBatch.FillRectangle(new Vector2(x, y), new Size2(1, 1), Color.Black); } } } // draw the path // in a real game, you'd obviously make your characters walk along the path instead of drawing it if (this.path != null) { for (var i = 1; i < this.path.Count; i++) { var first = this.path[i - 1]; var second = this.path[i]; this.SpriteBatch.DrawLine(new Vector2(first.X + 0.5F, first.Y + 0.5F), new Vector2(second.X + 0.5F, second.Y + 0.5F), Color.Blue, 0.25F); } } this.SpriteBatch.End(); base.DoDraw(gameTime); } } }