baseline: OpenMU upstream b5a0961 (fresh source)

src/GameLogic/DirectionExtensions.cs

@@ -0,0 +1,70 @@
+// <copyright file="DirectionExtensions.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameLogic;
+
+using MUnique.OpenMU.Pathfinding;
+
+/// <summary>
+/// Extension methods which have to do with handling <see cref="Direction"/>s.
+/// </summary>
+public static class DirectionExtensions
+{
+    /// <summary>
+    /// Calculates the target point based on the origin and the specified direction.
+    /// </summary>
+    /// <param name="origin">From point.</param>
+    /// <param name="direction">The direction.</param>
+    /// <returns>The target point based on the origin and the specified direction.</returns>
+    /// <exception cref="ArgumentException">direction.</exception>
+    public static Point CalculateTargetPoint(this Point origin, Direction direction)
+    {
+        return direction switch
+        {
+            Direction.Undefined => origin,
+            Direction.North => new Point((byte)(origin.X - 1), (byte)(origin.Y + 1)),
+            Direction.South => new Point((byte)(origin.X + 1), (byte)(origin.Y - 1)),
+            Direction.East => new Point((byte)(origin.X + 1), (byte)(origin.Y + 1)),
+            Direction.West => new Point((byte)(origin.X - 1), (byte)(origin.Y - 1)),
+            Direction.NorthEast => new Point(origin.X, (byte)(origin.Y + 1)),
+            Direction.NorthWest => new Point((byte)(origin.X - 1), origin.Y),
+            Direction.SouthEast => new Point((byte)(origin.X + 1), origin.Y),
+            Direction.SouthWest => new Point(origin.X, (byte)(origin.Y - 1)),
+            _ => throw new ArgumentException($"Direction value {direction} is not defined", nameof(direction)),
+        };
+    }
+
+    /// <summary>
+    /// Gets the direction from one point to another.
+    /// </summary>
+    /// <param name="from">The origin point.</param>
+    /// <param name="to">The target point.</param>
+    /// <returns>The direction from the origin to the target.</returns>
+    public static Direction GetDirectionTo(this Point from, Point to)
+    {
+        if (from == to)
+        {
+            return Direction.Undefined;
+        }
+
+        double angle = Math.Atan2(to.Y - from.Y, to.X - from.X);
+        angle += Math.PI;
+        angle /= Math.PI / 4;
+        int halfQuarter = Convert.ToInt32(angle);
+        halfQuarter %= 8;
+
+        return halfQuarter switch
+        {
+            7 => Direction.North,
+            0 => Direction.NorthWest,
+            1 => Direction.West,
+            2 => Direction.SouthWest,
+            3 => Direction.South,
+            4 => Direction.SouthEast,
+            5 => Direction.East,
+            6 => Direction.NorthEast,
+            _ => Direction.Undefined,
+        };
+    }
+}