features.py

import math


def append_landmarks(features, landmarks, anchor, scale, expected_count, use_visibility=False):
    if landmarks:
        for lm in landmarks.landmark:
            features.extend([
                (lm.x - anchor[0]) / scale,
                (lm.y - anchor[1]) / scale,
                (lm.z - anchor[2]) / scale,
            ])
            if use_visibility:
                features.append(lm.visibility)
    else:
        values_per_point = 4 if use_visibility else 3
        features.extend([0.0] * (expected_count * values_per_point))


def extract_features(pose_landmarks, left_hand_landmarks, right_hand_landmarks):
    if not pose_landmarks:
        return None

    left_shoulder = pose_landmarks.landmark[11]
    right_shoulder = pose_landmarks.landmark[12]

    anchor = (
        (left_shoulder.x + right_shoulder.x) / 2.0,
        (left_shoulder.y + right_shoulder.y) / 2.0,
        (left_shoulder.z + right_shoulder.z) / 2.0,
    )

    shoulder_dist = math.sqrt(
        (left_shoulder.x - right_shoulder.x) ** 2
        + (left_shoulder.y - right_shoulder.y) ** 2
        + (left_shoulder.z - right_shoulder.z) ** 2
    )
    scale = max(shoulder_dist, 1e-6)

    features = []
    append_landmarks(features, pose_landmarks, anchor, scale, expected_count=33, use_visibility=True)
    append_landmarks(features, left_hand_landmarks, anchor, scale, expected_count=21)
    append_landmarks(features, right_hand_landmarks, anchor, scale, expected_count=21)
    return features