为所有函数和类添加中文注释文档字符串

app/exercises/dead_bug/metrics.py

@@ -7,6 +7,7 @@ from app.exercises.dead_bug.types import Point
 
 
 def angle(a: Point, b: Point, c: Point) -> float:
+    """计算以b为顶点的三点夹角（度数）"""
     ba = np.array([a.x - b.x, a.y - b.y], dtype=np.float32)
     bc = np.array([c.x - b.x, c.y - b.y], dtype=np.float32)
     denom = float(np.linalg.norm(ba) * np.linalg.norm(bc))
@@ -17,6 +18,7 @@ def angle(a: Point, b: Point, c: Point) -> float:
 
 
 def distance(a: Point, b: Point) -> float:
+    """计算两点之间的欧几里得距离（归一化坐标空间）"""
     return float(np.hypot(a.x - b.x, a.y - b.y))
 
 
@@ -37,6 +39,7 @@ def calculate_metrics(
     right_ankle: int,
     visibility_threshold: float = 0.45,
 ) -> dict:
+    """计算四肢关节角度、伸展状态及反馈信息"""
     left_elbow_angle = angle(lm[left_shoulder], lm[left_elbow], lm[left_wrist])
     right_elbow_angle = angle(lm[right_shoulder], lm[right_elbow], lm[right_wrist])
     left_knee_angle = angle(lm[left_hip], lm[left_knee], lm[left_ankle])