add bindings to query gamepad's face buttons

ffi/glfw-input.c

@@ -66,3 +66,27 @@ float getLeftJoystickYAxisState() {
     return 99.0;
   }
 }
+
+int isCrossButtonPressed() {
+  return state.buttons[GLFW_GAMEPAD_BUTTON_CROSS];
+}
+
+int isCircleButtonPressed() {
+  return state.buttons[GLFW_GAMEPAD_BUTTON_CIRCLE];
+}
+
+int isSquareButtonPressed() {
+  return state.buttons[GLFW_GAMEPAD_BUTTON_SQUARE];
+}
+
+int isTriangleButtonPressed() {
+  return state.buttons[GLFW_GAMEPAD_BUTTON_TRIANGLE];
+}
+
+int isR1ButtonPressed() {
+  return state.buttons[GLFW_GAMEPAD_BUTTON_RIGHT_BUMPER];
+}
+
+int isL1ButtonPressed() {
+  return state.buttons[GLFW_GAMEPAD_BUTTON_LEFT_BUMPER];
+}

ffi/glfw-input.sml

@@ -53,6 +53,7 @@ struct
     _symbol "KEY_ARROW_DOWN" public : ( unit -> int ) * ( int -> unit );
   val KEY_ARROW_DOWN = KEY_ARROW_DOWN ()
 
+  (* gamepad bindings below *)
   val getGamepadState =
     _import "getGamepadState" public : int -> unit;
 
@@ -60,4 +61,17 @@ struct
     _import "getLeftJoystickXAxisState" public : unit -> Real32.real;
   val getLeftJoystickYAxisState =
     _import "getLeftJoystickYAxisState" public : unit -> Real32.real;
+
+  val isCrossButtonPressed =
+    _import "isCrossButtonPressed" public : unit -> int;
+  val isCircleButtonPressed =
+    _import "isCircleButtonPressed" public : unit -> int;
+  val isSquareButtonPressed =
+    _import "isSquareButtonPressed" public : unit -> int;
+  val isTriangleButtonPressed =
+    _import "isTriangleButtonPressed" public : unit -> int;
+  val isR1ButtonPressed =
+    _import "isR1ButtonPressed" public : unit -> int;
+  val isL1ButtonPressed =
+    _import "isL1ButtonPressed" public : unit -> int;
 end