Add page on controller-specific features (currently just LED)

tutorials/inputs/controller_features.rst

@@ -0,0 +1,94 @@
+.. _doc_controller_features:
+
+Controller features
+===================
+
+Godot supports controller-specific features that can further enhance the gameplay
+experience. This page describes these features, how existing games have used them,
+and how you can get started with them in Godot.
+
+.. warning::
+
+    These controller features are currently only supported on Windows, macOS, and Linux.
+
+
+.. warning::
+
+    Unless you specifically advertise your game as requiring specific controllers,
+    remember that there is no guarantee that players will have a controller with
+    any given features.
+
+    As a result, we suggest using these features to enhance the gameplay experience
+    for players whose controllers support them, without detracting from those who
+    don't have controllers.
+
+
+LED color
+---------
+
+Games can use the LED lights on certain controllers to subtly complement the on-screen gameplay by
+providing some matching visuals in the player's hands. Here are some notable examples:
+
+- In *Hades*, the color of the light matches the god you're receiving a boon from.
+- In *Resident Evil 2*, the color of the light indicates your health (green for full, yellow for medium, red for low).
+- In *Star Wars Jedi: Fallen Order*, the color of the light matches your lightsaber's color.
+
+Use the method :ref:`Input.set_joy_light()<class_Input_method_set_joy_light>` to set the color
+of a given controller's LEDs.
+
+To determine if a given controller supports setting LED lights, use the :ref:`Input.has_joy_light()<class_Input_method_has_joy_light>`
+method. The PlayStation DualShock and DualSense controllers are known to support LED lights.
+
+The following ``_process()`` method sets the LED color according to the currently pressed button,
+and turns it off if no button is being pressed:
+
+.. code-block::
+
+    func _process(_delta):
+        var color := Color.BLACK
+
+        if Input.is_joy_button_pressed(0, JOY_BUTTON_A):
+            color = Color.BLUE
+        elif Input.is_joy_button_pressed(0, JOY_BUTTON_X):
+            color = Color.MAGENTA
+        elif Input.is_joy_button_pressed(0, JOY_BUTTON_B):
+            color = Color.RED
+        elif Input.is_joy_button_pressed(0, JOY_BUTTON_Y):
+            color = Color.GREEN
+
+        Input.set_joy_light(0, color)
+
+
+The following example smoothly fades the LED through hues in a loop:
+
+.. code-block::
+
+    var hue = 0.0
+
+    func _process(delta):
+        var col = Color.from_hsv(hue, 1.0, 1.0)
+        Input.set_joy_light(0, col)
+        hue += delta * 0.1
+
+The following example makes the LED blink red three times when the south button (Cross/X on PlayStation controllers) is pressed:
+
+.. code-block::
+
+    var blink_tween: Tween = null
+
+    func _process(_delta):
+        var ready_to_blink = not blink_tween or not blink_tween.is_running()
+        if Input.is_joy_button_pressed(0, JOY_BUTTON_A) and ready_to_blink:
+            do_blink()
+
+    func do_blink():
+        if blink_tween:
+            blink_tween.kill()
+
+        blink_tween = create_tween()
+        blink_tween.tween_callback(func(): Input.set_joy_light(0, Color.RED))
+        blink_tween.tween_interval(0.2)
+        blink_tween.tween_callback(func(): Input.set_joy_light(0, Color.BLACK))
+        blink_tween.tween_interval(0.2)
+        blink_tween.set_loops(3)
+

tutorials/inputs/index.rst

@@ -12,4 +12,5 @@ Input handling
    mouse_and_input_coordinates
    custom_mouse_cursor
    controllers_gamepads_joysticks
+   controller_features
    handling_quit_requests