Server Fix (CORS and flatten import)

[pemmenegger]

Hi there,

I followed the tutorial and encountered 2 issues in server.py:

• from compas.utilities import flatten could not be imported
• Google Chrome failed to display the objects due to CORS issues

Here is my solution:

from typing import List

import uvicorn
from fastapi import FastAPI
from pydantic import BaseModel
from fastapi.middleware.cors import CORSMiddleware

import compas
from compas.geometry import Box
from compas.datastructures import Mesh
from compas.itertools import flatten


app = FastAPI()

origins = [
    "http://localhost:3000",  # Frontend origin
]

app.add_middleware(
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


class BoxInput(BaseModel):
    xsize: float
    ysize: float
    zsize: float


class MeshOutput(BaseModel):
    vertices: List[float]
    faces: List[int]
    edges: List[int]


def mesh_to_vertices_edges_triangles(mesh: Mesh) -> MeshOutput:
    vertices, faces = mesh.to_vertices_and_faces()
    triangles = []
    for face in faces:
        if len(face) == 3:
            triangles.append(face)
        elif len(face) == 4:
            triangles.append([face[0], face[1], face[2]])
            triangles.append([face[0], face[2], face[3]])
    edges = list(mesh.edges())
    return MeshOutput(
        vertices=list(flatten(vertices)),
        faces=list(flatten(triangles)),
        edges=list(flatten(edges)),
    )


@app.get("/ping")
async def ping():
    return 1


@app.get("/version")
async def version():
    return compas.__version__


@app.get("/load_tubemesh")
async def load_tubemesh() -> MeshOutput:
    mesh = Mesh.from_obj(compas.get("tubemesh.obj"))
    return mesh_to_vertices_edges_triangles(mesh)


@app.get("/load_bunny")
async def load_bunny() -> MeshOutput:
    mesh = Mesh.from_ply(compas.get("bunny.ply"))
    mesh.rotate(3.14159 / 2, [1, 0, 0])
    mesh.scale(30)
    return mesh_to_vertices_edges_triangles(mesh)


@app.post("/box_to_subdivided_mesh")
async def box_to_subdivided_mesh(boxdata: BoxInput) -> MeshOutput:
    box = Box(boxdata.xsize, boxdata.ysize, boxdata.zsize)
    mesh = box.to_mesh()
    ball = mesh.subdivided(k=3)
    return mesh_to_vertices_edges_triangles(ball)


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)

[tomvanmele]

hi,

thanks for taking the time. do you want to submit a PR so i can merge it into the tutorial?

best,
tom

[pemmenegger]

sure, but it seems that I'm not allowed to push branches to the repo...

[tomvanmele]

no, but you're allowed to submit a PR from a fork...