Geometry: add FMath class & convenient accessors for AABB corners.

The FMath class is like the System.Math class, but returns floats instead of
doubles so that you don't have to redundantly cast things.

GitOrigin-RevId: 0e1d7f46c7

Shared/Geometry.cs

@@ -5,6 +5,23 @@ using System;
 
 namespace SemiColinGames {
 
+  // Math functions that return floats rather than doubles, for convenience.
+  public static class FMath {
+    public const float PI = (float) Math.PI;
+
+    public static float DegToRad(float degrees) {
+      return PI / 180 * degrees;
+    }
+
+    public static float Sin(double degrees) {
+      return (float) Math.Sin(degrees);
+    }
+
+    public static float Cos(double degrees) {
+      return (float) Math.Cos(degrees);
+    }
+  }
+
   public readonly struct Hit {
     public readonly AABB Collider;
     public readonly Vector2 Position;
@@ -56,6 +73,38 @@ namespace SemiColinGames {
       HalfSize = halfSize;
     }
 
+    public float Top {
+      get { return Position.Y - HalfSize.Y; }
+    }
+
+    public float Bottom {
+      get { return Position.Y + HalfSize.Y; }
+    }
+
+    public float Left {
+      get { return Position.X - HalfSize.X; }
+    }
+
+    public float Right {
+      get { return Position.X + HalfSize.X; }
+    }
+
+    public Vector2 TopLeft {
+      get { return new Vector2(Left, Top); }
+    }
+
+    public Vector2 TopRight {
+      get { return new Vector2(Right, Top); }
+    }
+
+    public Vector2 BottomLeft {
+      get { return new Vector2(Left, Bottom); }
+    }
+
+    public Vector2 BottomRight {
+      get { return new Vector2(Right, Bottom); }
+    }
+
     public Hit? Intersect(AABB box) {
       float dx = box.Position.X - Position.X;
       float px = box.HalfSize.X + HalfSize.X - Math.Abs(dx);