Well I simply try for the beginning to create a texture that is half white and half black, however the box stays exactly identical as before.
@Override
protected void simpleInitGame() {
SceneMonitor.getMonitor().registerNode(this.rootNode);
SceneMonitor.getMonitor().showViewer(true);
Texture2D texture = new Texture2D();
Image image = new Image();
image.setWidth(2);
image.setHeight(2);
image.setFormat(Image.Format.Alpha8);
image.setMipMapSizes(null);
ByteBuffer data = ByteBuffer.allocate(4);
data.put((byte) 0);
data.put((byte) 0);
data.put((byte) 255);
data.put((byte) 255);
image.setData(data);
texture.setImage(image);
Box box = new Box("Keks",new Vector3f(0,0,0),1,1,1);
TextureState texturestate = DisplaySystem.getDisplaySystem().getRenderer().createTextureState();
texturestate.setTexture(texture);
box.setRenderState(texturestate);
this.rootNode.attachChild(box);
this.rootNode.updateRenderState();
}