REVIEWED: Avoid possible gamepad index as `-1` #2839

WARNING: It could require further review of `GamepadThread()` function where `js_event gamepadEvent.number` detecting current pressed button could generate a missmatch with index 0 (reserved for button unknow). Or maybe `0` could just be `GAMEPAD_BUTTON_NONE`? In that case, consistency with other inputs should be carefully considered...

src/raylib.h

@@ -716,7 +716,7 @@ typedef enum {
 
 // Material map index
 typedef enum {
-    MATERIAL_MAP_ALBEDO    = 0,     // Albedo material (same as: MATERIAL_MAP_DIFFUSE)
+    MATERIAL_MAP_ALBEDO = 0,        // Albedo material (same as: MATERIAL_MAP_DIFFUSE)
     MATERIAL_MAP_METALNESS,         // Metalness material (same as: MATERIAL_MAP_SPECULAR)
     MATERIAL_MAP_NORMAL,            // Normal material
     MATERIAL_MAP_ROUGHNESS,         // Roughness material
@@ -862,7 +862,7 @@ typedef enum {
 } BlendMode;
 
 // Gesture
-// NOTE: It could be used as flags to enable only some gestures
+// NOTE: Provided as bit-wise flags to enable only desired gestures
 typedef enum {
     GESTURE_NONE        = 0,        // No gesture
     GESTURE_TAP         = 1,        // Tap gesture

src/rcore.c

@@ -765,7 +765,7 @@ void InitWindow(int width, int height, const char *title)
     CORE.Input.Keyboard.exitKey = KEY_ESCAPE;
     CORE.Input.Mouse.scale = (Vector2){ 1.0f, 1.0f };
     CORE.Input.Mouse.cursor = MOUSE_CURSOR_ARROW;
-    CORE.Input.Gamepad.lastButtonPressed = -1;
+    CORE.Input.Gamepad.lastButtonPressed = 0;       // GAMEPAD_BUTTON_UNKNOWN
 #if defined(SUPPORT_EVENTS_WAITING)
     CORE.Window.eventWaiting = true;
 #endif
@@ -4871,7 +4871,7 @@ void PollInputEvents(void)
 
 #if !(defined(PLATFORM_RPI) || defined(PLATFORM_DRM))
     // Reset last gamepad button/axis registered state
-    CORE.Input.Gamepad.lastButtonPressed = -1;
+    CORE.Input.Gamepad.lastButtonPressed = 0;       // GAMEPAD_BUTTON_UNKNOWN
     CORE.Input.Gamepad.axisCount = 0;
 #endif
 
@@ -5714,14 +5714,15 @@ static int32_t AndroidInputCallback(struct android_app *app, AInputEvent *event)
             CORE.Input.Gamepad.ready[0] = true;
 
             GamepadButton button = AndroidTranslateGamepadButton(keycode);
-            if (button == GAMEPAD_BUTTON_UNKNOWN)
-                return 1;
+            
+            if (button == GAMEPAD_BUTTON_UNKNOWN) return 1;
 
             if (AKeyEvent_getAction(event) == AKEY_EVENT_ACTION_DOWN)
             {
                 CORE.Input.Gamepad.currentButtonState[0][button] = 1;
             }
             else CORE.Input.Gamepad.currentButtonState[0][button] = 0;  // Key up
+            
             return 1; // Handled gamepad button
         }
 
@@ -6685,7 +6686,7 @@ static void *GamepadThread(void *arg)
                         CORE.Input.Gamepad.currentButtonState[i][gamepadEvent.number] = (int)gamepadEvent.value;
 
                         if ((int)gamepadEvent.value == 1) CORE.Input.Gamepad.lastButtonPressed = gamepadEvent.number;
-                        else CORE.Input.Gamepad.lastButtonPressed = -1;
+                        else CORE.Input.Gamepad.lastButtonPressed = 0;       // GAMEPAD_BUTTON_UNKNOWN
                     }
                 }
                 else if (gamepadEvent.type == JS_EVENT_AXIS)