問題：
vue-3d-model.esm.js?e678:44779 Uncaught Error: OBJLoader: Unexpected line: "<!DOCTYPE html>"
at OBJLoader.parse (vue-3d-model.esm.js?e678:44779)
at Object.eval [as onLoad] (vue-3d-model.esm.js?e678:44589)
at XMLHttpRequest.eval (vue-3d-model.esm.js?e678:30476)
解決前：
<model-obj :backgroundAlpha="0"@on-load="onLoad" src="../../assets/models/tree.obj"></model-obj>
解決后：
<model-obj :backgroundAlpha="0"@on-load="onLoad" src="../static/models/tree.obj"></model-obj>
總結：您需要將模型放在公共文件夾中(static)，因為vue-cli會自動更改assets目錄中的資源路徑。