skin method

@override PathPoint skin(Mat2D world, Float32List? bones)

Implementation

@override
PathPoint skin(Mat2D world, Float32List? bones) {
  CubicPathPoint point = CubicPathPoint(pointType);

  double px =
      world[0] * translation[0] + world[2] * translation[1] + world[4];
  double py =
      world[1] * translation[0] + world[3] * translation[1] + world[5];

  {
    double a = 0.0, b = 0.0, c = 0.0, d = 0.0, e = 0.0, f = 0.0;

    for (int i = 0; i < 4; i++) {
      int boneIndex = _weights![i].floor();
      double weight = _weights![i + 4];
      if (weight > 0) {
        int bb = boneIndex * 6;

        a += bones![bb] * weight;
        b += bones[bb + 1] * weight;
        c += bones[bb + 2] * weight;
        d += bones[bb + 3] * weight;
        e += bones[bb + 4] * weight;
        f += bones[bb + 5] * weight;
      }
    }

    Vec2D pos = point.translation;
    pos[0] = a * px + c * py + e;
    pos[1] = b * px + d * py + f;
  }

  {
    double a = 0.0, b = 0.0, c = 0.0, d = 0.0, e = 0.0, f = 0.0;
    px = world[0] * _in[0] + world[2] * _in[1] + world[4];
    py = world[1] * _in[0] + world[3] * _in[1] + world[5];

    for (int i = 8; i < 12; i++) {
      int boneIndex = _weights![i].floor();
      double weight = _weights![i + 4];
      if (weight > 0) {
        int bb = boneIndex * 6;

        a += bones![bb] * weight;
        b += bones[bb + 1] * weight;
        c += bones[bb + 2] * weight;
        d += bones[bb + 3] * weight;
        e += bones[bb + 4] * weight;
        f += bones[bb + 5] * weight;
      }
    }

    Vec2D pos = point.inPoint;
    pos[0] = a * px + c * py + e;
    pos[1] = b * px + d * py + f;
  }

  {
    double a = 0.0, b = 0.0, c = 0.0, d = 0.0, e = 0.0, f = 0.0;
    px = world[0] * _out[0] + world[2] * _out[1] + world[4];
    py = world[1] * _out[0] + world[3] * _out[1] + world[5];

    for (int i = 16; i < 20; i++) {
      int boneIndex = _weights![i].floor();
      double weight = _weights![i + 4];
      if (weight > 0) {
        int bb = boneIndex * 6;

        a += bones![bb] * weight;
        b += bones[bb + 1] * weight;
        c += bones[bb + 2] * weight;
        d += bones[bb + 3] * weight;
        e += bones[bb + 4] * weight;
        f += bones[bb + 5] * weight;
      }
    }

    Vec2D pos = point.outPoint;
    pos[0] = a * px + c * py + e;
    pos[1] = b * px + d * py + f;
  }

  return point;
}