1 | using System; |
---|
2 | using System.Collections.Generic; |
---|
3 | using System.Linq; |
---|
4 | using System.Text; |
---|
5 | using System.Threading.Tasks; |
---|
6 | using Point = Microsoft.Xna.Framework.Point; |
---|
7 | |
---|
8 | namespace AStar |
---|
9 | { |
---|
10 | /// <summary> |
---|
11 | /// Represents a single node on a grid that is being searched for a path between two points |
---|
12 | /// </summary> |
---|
13 | public class Node |
---|
14 | { |
---|
15 | private Node parentNode; |
---|
16 | |
---|
17 | /// <summary> |
---|
18 | /// The node's location in the grid |
---|
19 | /// </summary> |
---|
20 | public Point Location { get; private set; } |
---|
21 | |
---|
22 | /// <summary> |
---|
23 | /// True when the node may be traversed, otherwise false |
---|
24 | /// </summary> |
---|
25 | public bool IsWalkable { get; set; } |
---|
26 | |
---|
27 | /// <summary> |
---|
28 | /// Cost from start to here |
---|
29 | /// </summary> |
---|
30 | public float G { get; private set; } |
---|
31 | |
---|
32 | /// <summary> |
---|
33 | /// Estimated cost from here to end |
---|
34 | /// </summary> |
---|
35 | public float H { get; private set; } |
---|
36 | |
---|
37 | /// <summary> |
---|
38 | /// Flags whether the node is open, closed or untested by the PathFinder |
---|
39 | /// </summary> |
---|
40 | public NodeState State { get; set; } |
---|
41 | |
---|
42 | /// <summary> |
---|
43 | /// Estimated total cost (F = G + H) |
---|
44 | /// </summary> |
---|
45 | public float F |
---|
46 | { |
---|
47 | get { return this.G + this.H; } |
---|
48 | } |
---|
49 | |
---|
50 | /// <summary> |
---|
51 | /// Gets or sets the parent node. The start node's parent is always null. |
---|
52 | /// </summary> |
---|
53 | public Node ParentNode |
---|
54 | { |
---|
55 | get { return this.parentNode; } |
---|
56 | set |
---|
57 | { |
---|
58 | // When setting the parent, also calculate the traversal cost from the start node to here (the 'G' value) |
---|
59 | this.parentNode = value; |
---|
60 | this.G = this.parentNode.G + GetTraversalCost(this.Location, this.parentNode.Location); |
---|
61 | } |
---|
62 | } |
---|
63 | |
---|
64 | /// <summary> |
---|
65 | /// Creates a new instance of Node. |
---|
66 | /// </summary> |
---|
67 | /// <param name="x">The node's location along the X axis</param> |
---|
68 | /// <param name="y">The node's location along the Y axis</param> |
---|
69 | /// <param name="isWalkable">True if the node can be traversed, false if the node is a wall</param> |
---|
70 | /// <param name="endLocation">The location of the destination node</param> |
---|
71 | public Node(int x, int y, bool isWalkable, Point endLocation) |
---|
72 | { |
---|
73 | this.Location = new Point(x, y); |
---|
74 | this.State = NodeState.Untested; |
---|
75 | this.IsWalkable = isWalkable; |
---|
76 | this.H = GetTraversalCost(this.Location, endLocation); |
---|
77 | this.G = 0; |
---|
78 | } |
---|
79 | |
---|
80 | public override string ToString() |
---|
81 | { |
---|
82 | return string.Format("{0}, {1}: {2}", this.Location.X, this.Location.Y, this.State); |
---|
83 | } |
---|
84 | |
---|
85 | /// <summary> |
---|
86 | /// Gets the distance between two points |
---|
87 | /// </summary> |
---|
88 | internal static float GetTraversalCost(Point location, Point otherLocation) |
---|
89 | { |
---|
90 | float deltaX = otherLocation.X - location.X; |
---|
91 | float deltaY = otherLocation.Y - location.Y; |
---|
92 | return (float)Math.Sqrt(deltaX * deltaX + deltaY * deltaY); |
---|
93 | } |
---|
94 | } |
---|
95 | } |
---|