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

{
  "__type__": "cc.Material",
  "_name": "",
  "_objFlags": 0,
  "_native": "",
  "_effectAsset": {
    "__uuid__": "c8f66d17-351a-48da-a12c-0212d28575c4"
  },
  "_techIdx": 0,
  "_defines": [],
  "_props": [
    {
      "roughness": 0.8,
      "metallic": 0.6
    }
  ]
}