updateHandFromLandmarks static method

void updateHandFromLandmarks(HandState state, List<Vector3> landmarks)

Maps a list of 21 MediaPipe 3D normalized landmark points x, y, z to HandState.

Implementation

static void updateHandFromLandmarks(
  HandState state,
  List<Vector3> landmarks,
) {
  if (landmarks.length < 21) {
    state.tracked = false;
    return;
  }

  state.tracked = true;

  // MediaPipe 21 Landmark mapping -> OpenXR 26 Joints
  state.joints[HandJoint.wrist] = landmarks[0];

  // Thumb
  state.joints[HandJoint.thumbMetacarpal] = landmarks[1];
  state.joints[HandJoint.thumbProximal] = landmarks[2];
  state.joints[HandJoint.thumbDistal] = landmarks[3];
  state.joints[HandJoint.thumbTip] = landmarks[4];

  // Index
  state.joints[HandJoint.indexMetacarpal] = landmarks[5];
  state.joints[HandJoint.indexProximal] = landmarks[6];
  state.joints[HandJoint.indexIntermediate] = landmarks[7];
  state.joints[HandJoint.indexDistal] = landmarks[8];
  state.joints[HandJoint.indexTip] = landmarks[8];

  // Middle
  state.joints[HandJoint.middleMetacarpal] = landmarks[9];
  state.joints[HandJoint.middleProximal] = landmarks[10];
  state.joints[HandJoint.middleIntermediate] = landmarks[11];
  state.joints[HandJoint.middleDistal] = landmarks[12];
  state.joints[HandJoint.middleTip] = landmarks[12];

  // Ring
  state.joints[HandJoint.ringMetacarpal] = landmarks[13];
  state.joints[HandJoint.ringProximal] = landmarks[14];
  state.joints[HandJoint.ringIntermediate] = landmarks[15];
  state.joints[HandJoint.ringDistal] = landmarks[16];
  state.joints[HandJoint.ringTip] = landmarks[16];

  // Little
  state.joints[HandJoint.littleMetacarpal] = landmarks[17];
  state.joints[HandJoint.littleProximal] = landmarks[18];
  state.joints[HandJoint.littleIntermediate] = landmarks[19];
  state.joints[HandJoint.littleDistal] = landmarks[20];
  state.joints[HandJoint.littleTip] = landmarks[20];

  // Palm is mid-point between wrist and middle metacarpal
  state.joints[HandJoint.palm] = (landmarks[0] + landmarks[9]) * 0.5;
}