@SuppressWarnings("null")
  public void draw(PolygonSpriteBatch batch, Skeleton skeleton) {
    boolean premultipliedAlpha = this.premultipliedAlpha;
    BlendMode blendMode = null;

    float[] vertices = null;
    short[] triangles = null;
    Array<Slot> drawOrder = skeleton.drawOrder;
    for (int i = 0, n = drawOrder.size; i < n; i++) {
      Slot slot = drawOrder.get(i);
      Attachment attachment = slot.attachment;
      Texture texture = null;
      if (attachment instanceof RegionAttachment) {
        RegionAttachment region = (RegionAttachment) attachment;
        vertices = region.updateWorldVertices(slot, premultipliedAlpha);
        triangles = quadTriangles;
        texture = region.getRegion().getTexture();

      } else if (attachment instanceof MeshAttachment) {
        MeshAttachment mesh = (MeshAttachment) attachment;
        vertices = mesh.updateWorldVertices(slot, premultipliedAlpha);
        triangles = mesh.getTriangles();
        texture = mesh.getRegion().getTexture();

      } else if (attachment instanceof WeightedMeshAttachment) {
        WeightedMeshAttachment mesh = (WeightedMeshAttachment) attachment;
        vertices = mesh.updateWorldVertices(slot, premultipliedAlpha);
        triangles = mesh.getTriangles();
        texture = mesh.getRegion().getTexture();

      } else if (attachment instanceof SkeletonAttachment) {
        Skeleton attachmentSkeleton = ((SkeletonAttachment) attachment).getSkeleton();
        if (attachmentSkeleton == null) continue;
        Bone bone = slot.getBone();
        Bone rootBone = attachmentSkeleton.getRootBone();
        float oldScaleX = rootBone.getScaleX();
        float oldScaleY = rootBone.getScaleY();
        float oldRotation = rootBone.getRotation();
        attachmentSkeleton.setPosition(
            skeleton.getX() + bone.getWorldX(), skeleton.getY() + bone.getWorldY());
        // rootBone.setScaleX(1 + bone.getWorldScaleX() - oldScaleX);
        // rootBone.setScaleY(1 + bone.getWorldScaleY() - oldScaleY);
        // Set shear.
        rootBone.setRotation(oldRotation + bone.getWorldRotationX());
        attachmentSkeleton.updateWorldTransform();

        draw(batch, attachmentSkeleton);

        attachmentSkeleton.setPosition(0, 0);
        rootBone.setScaleX(oldScaleX);
        rootBone.setScaleY(oldScaleY);
        rootBone.setRotation(oldRotation);
      }

      if (texture != null) {
        BlendMode slotBlendMode = slot.data.getBlendMode();
        if (slotBlendMode != blendMode) {
          blendMode = slotBlendMode;
          batch.setBlendFunction(blendMode.getSource(premultipliedAlpha), blendMode.getDest());
        }
        batch.draw(texture, vertices, 0, vertices.length, triangles, 0, triangles.length);
      }
    }
  }