From 5fb4265197c7d0ca297ff29c6e4acc47bb894341 Mon Sep 17 00:00:00 2001
From: Frank Tovar <mail@franktovar.de>
Date: Fri, 8 May 2026 22:10:57 +0200
Subject: [PATCH] Round dual terrain tile corners

---
 .../MainWindow.xaml.cs                        | 39 +++++++++++++++++--
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/src/ReactorMaintenance.Win2D/MainWindow.xaml.cs b/src/ReactorMaintenance.Win2D/MainWindow.xaml.cs
index 28d7f9a..557c037 100644
--- a/src/ReactorMaintenance.Win2D/MainWindow.xaml.cs
+++ b/src/ReactorMaintenance.Win2D/MainWindow.xaml.cs
@@ -4,6 +4,7 @@ using Windows.Storage;
 using Windows.Storage.Pickers;
 using Windows.UI;
 using Microsoft.Graphics.Canvas;
+using Microsoft.Graphics.Canvas.Geometry;
 using Microsoft.Graphics.Canvas.Text;
 using Microsoft.Graphics.Canvas.UI.Xaml;
 using Microsoft.UI;
@@ -228,22 +229,52 @@ public sealed partial class MainWindow
         var halfWidth = rect.Width / 2;
         var halfHeight = rect.Height / 2;
         if ((floorMask & c_TopLeftFloor) != 0)
-            drawing.FillRectangle(new(rect.X, rect.Y, halfWidth, halfHeight), floorColor);
+            DrawFloorCorner(drawing, rect, floorColor, c_TopLeftFloor);
 
         if ((floorMask & c_TopRightFloor) != 0)
-            drawing.FillRectangle(new(rect.X + halfWidth, rect.Y, halfWidth, halfHeight), floorColor);
+            DrawFloorCorner(drawing, rect, floorColor, c_TopRightFloor);
 
         if ((floorMask & c_BottomLeftFloor) != 0)
-            drawing.FillRectangle(new(rect.X, rect.Y + halfHeight, halfWidth, halfHeight), floorColor);
+            DrawFloorCorner(drawing, rect, floorColor, c_BottomLeftFloor);
 
         if ((floorMask & c_BottomRightFloor) != 0)
-            drawing.FillRectangle(new(rect.X + halfWidth, rect.Y + halfHeight, halfWidth, halfHeight), floorColor);
+            DrawFloorCorner(drawing, rect, floorColor, c_BottomRightFloor);
 
         var center = new Vector2((float)(rect.X + halfWidth), (float)(rect.Y + halfHeight));
         if (floorMask is c_TopLeftFloor or c_TopRightFloor or c_BottomLeftFloor or c_BottomRightFloor)
             drawing.FillCircle(center, (float)Math.Min(rect.Width, rect.Height) * 0.18f, floorColor);
     }
 
+    private static void DrawFloorCorner(CanvasDrawingSession drawing, Rect rect, Color color, int corner)
+    {
+        var center = new Vector2((float)(rect.X + rect.Width / 2), (float)(rect.Y + rect.Height / 2));
+        var radiusX = (float)rect.Width / 2;
+        var radiusY = (float)rect.Height / 2;
+        var start = corner switch {
+            c_TopLeftFloor => new Vector2(center.X, (float)rect.Y),
+            c_TopRightFloor => new Vector2((float)(rect.X + rect.Width), center.Y),
+            c_BottomRightFloor => new Vector2(center.X, (float)(rect.Y + rect.Height)),
+            c_BottomLeftFloor => new Vector2((float)rect.X, center.Y),
+            _ => center
+        };
+        var end = corner switch {
+            c_TopLeftFloor => new Vector2((float)rect.X, center.Y),
+            c_TopRightFloor => new Vector2(center.X, (float)rect.Y),
+            c_BottomRightFloor => new Vector2((float)(rect.X + rect.Width), center.Y),
+            c_BottomLeftFloor => new Vector2(center.X, (float)(rect.Y + rect.Height)),
+            _ => center
+        };
+
+        using var builder = new CanvasPathBuilder(drawing);
+        builder.BeginFigure(center);
+        builder.AddLine(start);
+        builder.AddArc(end, radiusX, radiusY, 0, CanvasSweepDirection.CounterClockwise, CanvasArcSize.Small);
+        builder.EndFigure(CanvasFigureLoop.Closed);
+
+        using var geometry = CanvasGeometry.CreatePath(builder);
+        drawing.FillGeometry(geometry, color);
+    }
+
     private int GetDualTileMask(int x, int y)
     {
         var mask = 0;