Document hiDPI support in Multiple resolutions

tutorials/rendering/multiple_resolutions.rst

@@ -251,6 +251,28 @@ To configure stretching at runtime from a script, use the
 ``get_tree().set_screen_stretch()`` method (see
 :ref:`SceneTree.set_screen_stretch() <class_SceneTree_method_set_screen_stretch>`).
 
+hiDPI support
+-------------
+
+By default, Godot projects aren't considered DPI-aware by the operating system.
+This is done to improve performance on low-end systems, since the operating
+system's DPI fallback scaling will be faster than letting the application scale
+itself (even when using the ``viewport`` stretch mode).
+
+However, the OS-provided DPI fallback scaling doesn't play well with fullscreen
+mode. If you want crisp visuals on hiDPI displays or if project uses fullscreen,
+it's recommended to enable **Display > Window > Dpi > Allow Hidpi** in the
+Project Settings.
+
+**Allow Hidpi** is only effective on Windows and macOS. It's ignored on all
+other platforms.
+
+.. note::
+
+    The Godot editor itself is always marked as DPI-aware. Running the project
+    from the editor will only be DPI-aware if **Allow Hidpi** is enabled in the
+    Project Settings.
+
 Reducing aliasing on downsampling
 ---------------------------------