graph自动生成
读取正在运行的场景结构：输入、参数、节点、输出。
The running scene’s structure.
{"id": 1, "op": "graph"}此操作不带字段。
inputs, params, nodes, outputs (each with its source, and to: the Host device it is given to, or null), fonts (each font node: id, path, codes, its outputs and the inputs they are in), files (each files node: id, path, paths, its outputs and the inputs they are in), fields (each fields node: id, type, path, paths, its outputs and the inputs they are in)