teddy_controller.dart

import 'dart:math';
import 'dart:ui';

import 'package:flare_flutter/flare.dart';
import 'package:flare_flutter/flare_controls.dart';

class TeddyController extends FlareControls {
  // Store a reference to our face control node (the "ctrl_look" node in Flare)
  ActorNode? _faceControl;

  // Storage for our matrix to get global Flutter coordinates into Flare world coordinates.
  Mat2D _globalToFlareWorld = Mat2D();

  // Caret in Flutter global coordinates.
  Vec2D _caretGlobal = Vec2D();

  // Caret in Flare world coordinates.
  Vec2D _caretWorld = Vec2D();

  // Store the origin in both world and local transform spaces.
  Vec2D _faceOrigin = Vec2D();
  Vec2D _faceOriginLocal = Vec2D();

  bool _hasFocus = false;

  // Project gaze forward by this many pixels.
  static const double _projectGaze = 60.0;

  String _password = '???';

  @override
  bool advance(FlutterActorArtboard artboard, double elapsed) {
    super.advance(artboard, elapsed);
    if (_faceControl?.parent == null) {
      return false;
    }
    Vec2D targetTranslation;
    if (_hasFocus) {
      // Get caret in Flare world space.
      Vec2D.transformMat2D(_caretWorld, _caretGlobal, _globalToFlareWorld);

      // To make it more interesting, we'll also add a sinusoidal vertical offset.
      _caretWorld[1] +=
          sin(new DateTime.now().millisecondsSinceEpoch / 300.0) * 70.0;

      // Compute direction vector.
      Vec2D toCaret = Vec2D.subtract(Vec2D(), _caretWorld, _faceOrigin);
      Vec2D.normalize(toCaret, toCaret);
      Vec2D.scale(toCaret, toCaret, _projectGaze);

      // Compute the transform that gets us in face "ctrl_face" space.
      Mat2D toFaceTransform = Mat2D();
      if (Mat2D.invert(toFaceTransform, _faceControl!.parent!.worldTransform)) {
        // Put toCaret in local space, note we're using a direction vector
        // not a translation so transform without translation
        Vec2D.transformMat2(toCaret, toCaret, toFaceTransform);
        // Our final "ctrl_face" position is the original face translation plus this direction vector
        targetTranslation = Vec2D.add(Vec2D(), toCaret, _faceOriginLocal);
      } else {
        targetTranslation = Vec2D();
      }
    } else {
      targetTranslation = Vec2D.clone(_faceOriginLocal);
    }

    // We could just set _faceControl.translation to targetTranslation, but we want to animate it smoothly to this target
    // so we interpolate towards it by a factor of elapsed time in order to maintain speed regardless of frame rate.
    Vec2D diff =
        Vec2D.subtract(Vec2D(), targetTranslation, _faceControl!.translation);
    Vec2D frameTranslation = Vec2D.add(Vec2D(), _faceControl!.translation,
        Vec2D.scale(diff, diff, min(1.0, elapsed * 5.0)));

    _faceControl!.translation = frameTranslation;

    return true;
  }

  // Fetch references for the `ctrl_face` node and store a copy of its original translation.
  @override
  void initialize(FlutterActorArtboard artboard) {
    super.initialize(artboard);
    _faceControl = artboard.getNode("ctrl_face");
    if (_faceControl != null) {
      _faceControl!.getWorldTranslation(_faceOrigin);
      Vec2D.copy(_faceOriginLocal, _faceControl!.translation);
    }
    play("idle");
  }

  @override
  onCompleted(String name) {
    play("idle");
  }

  // Called by [FlareActor] when the view transform changes.
  // Updates the matrix that transforms Global-Flutter-coordinates into Flare-World-coordinates.
  @override
  void setViewTransform(Mat2D viewTransform) {
    Mat2D.invert(_globalToFlareWorld, viewTransform);
  }

  // Transform the [Offset] into a [Vec2D].
  // If no caret is provided, lower the [_hasFocus] flag.
  void lookAt(Offset? caret) {
    if (caret == null) {
      _hasFocus = false;
      return;
    }
    _caretGlobal[0] = caret.dx;
    _caretGlobal[1] = caret.dy;
    _hasFocus = true;
  }

  void setPassword(String value) {
    _password = value;
  }

  bool _isCoveringEyes = false;
  coverEyes(cover) {
    if (_isCoveringEyes == cover) {
      return;
    }
    _isCoveringEyes = cover;
    if (cover) {
      play("hands_up");
    } else {
      play("hands_down");
    }
  }

  void submitPassword() {
    if (_password == "bears") {
      play("success");
    } else {
      play("fail");
    }
  }
}