Add stalemate detection

README.md

@@ -1,6 +1,8 @@
 Little Update:
 ![image](https://github.com/user-attachments/assets/4c684cd1-d46d-4c61-8e63-618654657924)
 Little Chess Game I created in half an hour using the ursina engine.
+
+Press **U** or click the **Undo** button to take back the last move.
 ![image](https://github.com/user-attachments/assets/1a8473b1-2445-497e-b5cf-9efe9afd0f87)
 ![image](https://github.com/user-attachments/assets/b01c78aa-bc15-4699-ac12-6a2f091d6251)
 ![image](https://github.com/user-attachments/assets/dbc30499-e322-4cb6-9f80-623c3cbe6e17)

chess_game.py

@@ -41,6 +41,7 @@ def centered_text(msg: str, col, duration: float = 1.5):
     return btn
 
 move_display = None
+undo_button = None
 
 
 def enable_board_input(state: bool):
@@ -55,6 +56,15 @@ def update_board():
     move_display.text = board.peek().uci() if board.move_stack else ''
 
 
+def undo_move():
+    if not board.move_stack:
+        return
+    board.pop()
+    update_board()
+    clear_highlights()
+    clicked.clear()
+
+
 
 def ask_promotion(base_move: str):
     enable_board_input(False)
@@ -76,6 +86,8 @@ def choose(letter: str):
             centered_text('Check!', color.red)
         if board.is_checkmate():
             centered_text('Checkmate!', color.gold)
+        if board.is_stalemate():
+            centered_text('Stalemate!', color.gold)
 
     for i, (letter, glyph) in enumerate(pieces):
         b = Button(
@@ -137,6 +149,8 @@ def handle_click(square_name: str):
             centered_text('Check!', color.red)
         if board.is_checkmate():
             centered_text('Checkmate!', color.gold)
+        if board.is_stalemate():
+            centered_text('Stalemate!', color.gold)
     except chess.IllegalMoveError:
         if needs_promotion(move):
             ask_promotion(move)
@@ -178,7 +192,7 @@ def needs_promotion(base_move: str) -> bool:
 
 
 def layout_board():
-    global tile_len, move_display
+    global tile_len, move_display, undo_button
     aspect = window.aspect_ratio
     tile_len = 1 / 8
     if aspect < 1:
@@ -203,12 +217,29 @@ def layout_board():
             text='',
         )
 
+    if undo_button is None:
+        undo_button = Button(
+            parent=move_display,
+            text='Undo',
+            color=color.azure,
+            text_color=color.black,
+            on_click=undo_move,
+            radius=0,
+        )
+    else:
+        undo_button.parent = move_display
+
     a8_pos = squares['a8'].position
     move_display.scale = (tile_len * .9, tile_len * .9)
     move_display.position = (a8_pos[0], a8_pos[1])
     move_display.origin = (0, 0)
     move_display.z = -0.1
 
+    undo_button.scale = move_display.scale
+    undo_button.position = (move_display.scale_x * 1.1, 0)
+    undo_button.origin = (0, 0)
+    undo_button.z = -0.1
+
 
 
 layout_board()
@@ -224,4 +255,9 @@ def update():
         _prev = window.size
 
 
+def input(key):
+    if key == 'u':
+        undo_move()
+
+
 app.run()