Gltf model exported from Blender is always black in Three.js

[zed87]

I am trying to import in my Three.js project a gltf model exported from Blender.

The problem is that, in Three.js, all models materials are black (color: Color {r: 1, g: 1, b: 1}) while originally the mesh is green.

I find this topic

(http://www.html5gamedevs.com/topic/41196-object-always-exports-black-3dsmax-gltf-export/)

that show how to solve the problem in 3dsmax, but how to solve for blender?

Here my code in Three.js:   

var loader= new THREE.GLTFLoader();
loader.load(
  'http://localhost/planegeometryeditor/meshes/map/firstterrain.gltf', 
  function(gltf) { scene.add(gltf.scene); },
  undefined, 
  function (error) { console.error(error); }
);