# Control Avatar (ARKit)

## Background

Motion capture results should be provided to allow MYTY Avatars to reflect the movement of users. This interface defines how to deliver the ARKit results.

## Input parameters

### FacePosition

Normalized position of detected face. This is used to position AR Face in the screen.

### FaceScale

Scale of detected face. This is used to scale AR Face in the screen.

### Up

Up vector of detected face. This is used to rotate head around the z-axis in FullBody mode.

### Forward

Forward vector of detected face. This is used to rotate head around the y-axis in FullBody mode.

### Blendshapes

Blendshape results from AR Kit. This is used to apply facial expressions to MYTY Avatar. As of April 2023, MYTY SDK uses coefficients below.

> <mark style="color:purple;">`browDownLeft`</mark>, <mark style="color:purple;">`browDownRight`</mark>, <mark style="color:purple;">`browOuterUpLeft`</mark>, <mark style="color:purple;">`browOuterUpRight`</mark>, <mark style="color:purple;">`eyeBlinkLeft`</mark>, <mark style="color:purple;">`eyeBlinkRight`</mark>, <mark style="color:purple;">`jawOpen`</mark>, <mark style="color:purple;">`mouthClose`</mark>, <mark style="color:purple;">`mouthPucker`</mark>, <mark style="color:purple;">`mouthSmileLeft`</mark>, <mark style="color:purple;">`mouthSmileRight`</mark>, <mark style="color:purple;">`mouthStretchLeft`</mark>, <mark style="color:purple;">`mouthStretchRight`</mark>

For more details about blendshape in ARKit, you can refer to the document below.

{% embed url="<https://developer.apple.com/documentation/arkit/arfaceanchor/2928251-blendshapes>" %}

## Example Usage (Dart)

```dart
context.read<UnityBloc>().add(
    UnityMotionCapturedEvent(
      arKitData: ARKitData(
        facePosition: vm.Vector3(screenCoordinates.x / screenWidth,
            screenCoordinates.y / screenHeight, 0),
        faceScale: vm.Vector3(0.35 / facePosition.length,
            0.35 / facePosition.length, 0.35 / facePosition.length),
        up: vm.Vector3(-upVector.x, upVector.y, upVector.z),
        forward: anchor.transform.forward,
        blendshapes: ARKitBlendShape(
            browDownLeft: anchor.blendShapes['browDown_L'] ?? 0,
            browDownRight: anchor.blendShapes['browDown_R'] ?? 0,
            browOuterUpLeft: anchor.blendShapes['browOuterUp_L'] ?? 0,
            browOuterUpRight: anchor.blendShapes['browOuterUp_R'] ?? 0,
            eyeBlinkLeft: anchor.blendShapes['eyeBlink_L'] ?? 0,
            eyeBlinkRight: anchor.blendShapes['eyeBlink_R'] ?? 0,
            jawOpen: anchor.blendShapes['jawOpen'] ?? 0,
            mouthClose: anchor.blendShapes['mouthClose'] ?? 0,
            mouthPucker: anchor.blendShapes['mouthPucker'] ?? 0,
            mouthSmileLeft: anchor.blendShapes['mouthSmile_L'] ?? 0,
            mouthSmileRight: anchor.blendShapes['mouthSmile_R'] ?? 0,
            mouthStretchLeft: anchor.blendShapes['mouthStretch_L'] ?? 0,
            mouthStretchRight: anchor.blendShapes['mouthStretch_R'] ?? 0),
      ),
    ),
  );
```


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