code: public void prepare (int tint, AffineTransform xf) {
      prepare(tint, xf.m00, xf.m01, xf.m10, xf.m11, xf.tx, xf.ty);
    }
docs: Prepares to add primitives with the specified tint and transform. This configures
  {@link #stableAttrs} with all of the attributes that are the same for every vertex.