public void FaceOffsetCalculation (UInt16 [] vertices, UInt16 texture_and_result) {
var face3 = new libtrx.Face3 (vertices.Take (3).ToArray (), texture_and_result);
var face4 = new libtrx.Face4 (vertices, texture_and_result);
Assert.AreEqual (texture_and_result, face3.Texture);
Assert.AreEqual (texture_and_result, face4.Texture);
}