make pymunk imports optional, which allows to exclude it during packa…

…ging with cx_freeze

arcade/__init__.py

@@ -199,9 +199,12 @@ def configure_logging(level: int | None = None):
 from .tilemap import read_tmx
 from .tilemap import TileMap
 
-from .pymunk_physics_engine import PymunkPhysicsEngine
-from .pymunk_physics_engine import PymunkPhysicsObject
-from .pymunk_physics_engine import PymunkException
+try:
+    from .pymunk_physics_engine import PymunkPhysicsEngine
+    from .pymunk_physics_engine import PymunkPhysicsObject
+    from .pymunk_physics_engine import PymunkException
+except ImportError:
+    print("Pymunk is not installed. Pymunk physics engine will not be available.")
 
 from .version import VERSION
 

arcade/hitbox/__init__.py

@@ -6,18 +6,23 @@
 
 from .base import HitBox, HitBoxAlgorithm, RotatableHitBox
 from .bounding_box import BoundingHitBoxAlgorithm
-from .pymunk import PymunkHitBoxAlgorithm
 from .simple import SimpleHitBoxAlgorithm
 
 #: The simple hit box algorithm.
 algo_simple = SimpleHitBoxAlgorithm()
-#: The detailed hit box algorithm.
-algo_detailed = PymunkHitBoxAlgorithm()
 #: The bounding box hit box algorithm.
 algo_bounding_box = BoundingHitBoxAlgorithm()
 #: The default hit box algorithm.
 algo_default = algo_simple
 
+#: The detailed hit box algorithm, if pymunk available.
+try:
+    from .pymunk import PymunkHitBoxAlgorithm
+    algo_detailed = PymunkHitBoxAlgorithm()
+except ImportError:
+    algo_detailed = None
+    print("Warning: pymunk is not installed. PymunkHitBoxAlgorithm will not be available.")
+
 
 # Temporary functions for backwards compatibility
 def calculate_hit_box_points_simple(image: Image, *args) -> Point2List:
@@ -46,6 +51,7 @@ def calculate_hit_box_points_detailed(
             How detailed to make the hit box. There's a
             trade-off in number of points vs. accuracy.
     """
+    assert algo_detailed, "PymunkHitBoxAlgorithm is not available."
     return algo_detailed.calculate(image, detail=hit_box_detail)