scaler script

ResolutionScaler.cs

@@ -0,0 +1,68 @@
+using Microsoft.Xna.Framework;
+
+namespace ResolutionScaler
+{
+    static class ResolutionScaler
+    {
+        static private int s_virtual_width;
+        static private int s_virtual_height;
+        static private int s_screen_width;
+        static private int s_screen_height;
+
+        static private Matrix s_transform_matrix;
+        static private bool s_dirtyMatrix = true;
+
+        static public void Init(int screenWidth, int screenHeight, int virtualWidth, int virtualHeight)
+        {
+            s_screen_width = screenWidth;
+            s_screen_height = screenHeight;
+            s_virtual_width = virtualWidth;
+            s_virtual_height = virtualHeight;
+            s_dirtyMatrix = true;
+        }
+
+        static public Matrix TransformMatrix
+        {
+            get
+            {
+                if (s_dirtyMatrix) RecreateScaleMatrix();
+                return s_transform_matrix;
+            }
+        }
+
+        static public void SetScreenResolution(int width, int height)
+        {
+            s_screen_width = width;
+            s_screen_height = height;
+            s_dirtyMatrix = true;
+        }
+
+        static public void SetVirtualResolution(int width, int height)
+        {
+            s_virtual_width = width;
+            s_virtual_height = height;
+            s_dirtyMatrix = true;
+        }
+
+        static private void RecreateScaleMatrix()
+        {
+            var scaleUniform = System.Math.Min(
+                (float)s_screen_width / s_virtual_width,
+                (float)s_screen_height / s_virtual_height
+            );
+
+            var scaleMatrix = Matrix.CreateScale(
+                (float)scaleUniform,
+                (float)scaleUniform,
+                1f
+            );
+
+            var offX = (s_screen_width - scaleUniform * s_virtual_width) / 2;
+            var offY = (s_screen_height - scaleUniform * s_virtual_height) / 2;
+            var translationMatrix = Matrix.CreateTranslation(offX, offY, 0);
+
+            s_transform_matrix = scaleMatrix * translationMatrix;
+            s_dirtyMatrix = false;
+        }
+    }
+}