cocos-creator-template/assets/default_materials/default-material.mtl

{
  "__type__": "cc.Material",
  "_name": "",
  "_objFlags": 0,
  "_native": "",
  "_effectAsset": {
    "__uuid__": "1baf0fc9-befa-459c-8bdd-af1a450a0319"
  },
  "_techIdx": 0,
  "_defines": [
    {}
  ],
  "_props": [
    {
      "roughness": 0.8,
      "metallic": 0.6
    }
  ]
}