@Override
    public void simpleUpdate(float tpf) {
        if (t == -1 || t > 5) {
            t = 0;
            loadModel(new Vector3f(0, 0, 0), 3, modelType, materialType);
            materialType++;
            if (materialType >= maxMaterials) {
                materialType = 0;
                modelType++;
                if (modelType >= maxModels) {
                    modelType = 0;
                }
            }
        }
        t += tpf;

    }
This test cycles through a model exported in different formats and with different materials with tangents
generated in different ways. The normal map should look correct in all cases. Refer to
https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/NormalTangentMirrorTest for details on
the correct result and debugging.
jme3-examples/src/main/java/jme3test/material/TestNormalMappingConsistency.java