Code smells

PathFinding/Direction.cs

@@ -0,0 +1,18 @@
+using System.Numerics;
+
+namespace PathFinding
+{
+  public static class Direction
+  {
+    public static readonly Vector2 Up = new(0, 1);
+    public static readonly Vector2 Down = new(0, -1);
+    public static readonly Vector2 Left = new(-1, 0);
+    public static readonly Vector2 Right = new(1, 0);
+    public static readonly Vector2 UpLeft = new(-1, 1);
+    public static readonly Vector2 UpRight = new(1, 1);
+    public static readonly Vector2 DownLeft = new(-1, -1);
+    public static readonly Vector2 DownRight = new(1, -1);
+    public static readonly Vector2 KnightLeft = new(-1, 2);
+    public static readonly Vector2 KnightRight = new(1, 2);
+  }
+}

PathFinding/Distance.cs

@@ -0,0 +1,8 @@
+namespace PathFinding
+{
+  public enum Distance
+  {
+    OneStep,
+    MultiStep
+  }
+}

PathFinding/Enums.cs

@@ -1,19 +0,0 @@
-namespace PathFinding
-{
-  public enum HaltCondition
-  {
-    /// <summary>
-    /// Do not stop until you reach the collection boundary.
-    /// </summary>
-    None,
-    /// <summary>
-    /// Halt after encountering a non-null element.
-    /// </summary>
-    AfterCollide
-  }
-}
-public enum Distance
-{
-  OneStep,
-  MultiStep
-}

PathFinding/IPlanarCollection.cs

@@ -2,7 +2,7 @@
 
 namespace PathFinding
 {
-  public interface IPlanarCollection<T> : IEnumerable<T>
+  public interface IPlanarCollection<T> : IEnumerable<T> where T : IPlanarElement
   {
     T this[float x, float y] { get; set; }
     int GetLength(int dimension);

PathFinding/IPlanarElement.cs

@@ -1,12 +1,9 @@
 
-using System.Collections.Generic;
-
 namespace PathFinding
 {
   public interface IPlanarElement
   {
-    ICollection<Path> GetPaths();
-
+    MoveSet MoveSet { get; }
     bool IsUpsideDown { get; }
   }
 }

PathFinding/Move.cs

@@ -4,11 +4,11 @@ using System.Numerics;
 namespace PathFinding
 {
   [DebuggerDisplay("{Direction} - {Distance}")]
-  public class Path
+  public class Move
   {
     public Vector2 Direction { get; }
     public Distance Distance { get; }
-    public Path(Vector2 direction, Distance distance = Distance.OneStep)
+    public Move(Vector2 direction, Distance distance = Distance.OneStep)
     {
       Direction = direction;
       Distance = distance;

PathFinding/MoveSet.cs

@@ -0,0 +1,23 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+
+namespace PathFinding
+{
+  public class MoveSet
+  {
+    private readonly IPlanarElement element;
+    private readonly ICollection<Move> moves;
+    private readonly ICollection<Move> upsidedownMoves;
+
+    public MoveSet(IPlanarElement element, ICollection<Move> moves)
+    {
+      this.element = element;
+      this.moves = moves;
+      upsidedownMoves = moves.Select(_ => new Move(Vector2.Negate(_.Direction), _.Distance)).ToList();
+    }
+
+    public ICollection<Move> GetMoves() => element.IsUpsideDown ? upsidedownMoves : moves;
+
+  }
+}

PathFinding/PathFinder2D.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Linq;
 using System.Numerics;
 
@@ -13,7 +12,6 @@ namespace PathFinding
     /// <param name="position"></param>
     public delegate void Callback(T collider, Vector2 position);
 
-
     private readonly IPlanarCollection<T> collection;
     private readonly int width;
     private readonly int height;
@@ -39,8 +37,9 @@ namespace PathFinding
         return false;
       }
       var element = collection[origin.X, origin.Y];
-      var path = FindDirectionTowardsDestination(element.GetPaths(), origin, destination);
+      if (element == null) return false;
 
+      var path = FindDirectionTowardsDestination(element.MoveSet.GetMoves(), origin, destination);
       if (!IsPathable(origin, destination, path.Direction))
       {
         // Assumption: if a single best-choice step towards the destination cannot happen, no pathing can happen.
@@ -69,7 +68,7 @@ namespace PathFinding
     public void PathEvery(Vector2 from, Callback callback)
     {
       var element = collection[from.X, from.Y];
-      foreach (var path in element.GetPaths())
+      foreach (var path in element.MoveSet.GetMoves())
       {
         var shouldPath = true;
         var next = Vector2.Add(from, path.Direction); ;
@@ -106,16 +105,15 @@ namespace PathFinding
       }
     }
 
-    public Path FindDirectionTowardsDestination(ICollection<Path> paths, Vector2 origin, Vector2 destination) =>
+    public static Move FindDirectionTowardsDestination(ICollection<Move> paths, Vector2 origin, Vector2 destination) =>
       paths.Aggregate((a, b) => Vector2.Distance(destination, Vector2.Add(origin, a.Direction)) < Vector2.Distance(destination, Vector2.Add(origin, b.Direction)) ? a : b);
 
-
-    public bool IsPathable(Vector2 origin, Vector2 destination, T element)
+    public static bool IsPathable(Vector2 origin, Vector2 destination, T element)
     {
-      var path = FindDirectionTowardsDestination(element.GetPaths(), origin, destination);
+      var path = FindDirectionTowardsDestination(element.MoveSet.GetMoves(), origin, destination);
       return IsPathable(origin, destination, path.Direction);
     }
-    public bool IsPathable(Vector2 origin, Vector2 destination, Vector2 direction)
+    public static bool IsPathable(Vector2 origin, Vector2 destination, Vector2 direction)
     {
       direction = Vector2.Normalize(direction);
       var next = Vector2.Add(origin, direction);

PathFinding/PathFinding.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <TargetFramework>net5.0</TargetFramework>
     <EnableNETAnalyzers>true</EnableNETAnalyzers>
+    <AnalysisLevel>5</AnalysisLevel>
   </PropertyGroup>
 
 </Project>