Variable assignment with SceneLoader()

Questions
1

var hero;

        BABYLON.SceneLoader.ImportMesh("hero", "./scenes/", "girl.glb", scene, function (newMeshes, particleSystems, skeletons, animationGroups) {

            hero = newMeshes[0];

            //this can read variables outside ImportMesh() but cannot give them value after the end bracket.

        });

        //error here because hero is undefined

        hero.position = new BABYLON.Vector3(3.7,-5,-10);

        hero.ellipsoid = new BABYLON.Vector3(0.5, 1.0, 0.5);

        hero.ellipsoidOffset = new BABYLON.Vector3(0, 1.0, 0);

        scene.gravity = new BABYLON.Vector3(0, -0.9, 0);
2

Hi @fire7side, this is because ImportMesh is fundamentally an asynchronous operation – it takes some time to complete, and the browser can’t hang around forever waiting for it to complete – so the ImportMesh function is immediately evaluated and the program continues to run.

You have two options.

  1. Put your code that relies on hero inside the callback
  2. Make your function async (which means it returns a Promise) and await the result. There is a separate API for this path called “ImportMeshAsync” (in general any scene loader operations have an ^Async version).

1 would look like this:

BABYLON.SceneLoader.ImportMesh("hero", "./scenes/", "girl.glb", scene, function (newMeshes, particleSystems, skeletons, animationGroups) {
        hero = newMeshes[0];
        hero.position = new BABYLON.Vector3(3.7,-5,-10);
        hero.ellipsoid = new BABYLON.Vector3(0.5, 1.0, 0.5);
        hero.ellipsoidOffset = new BABYLON.Vector3(0, 1.0, 0);
});

scene.gravity = new BABYLON.Vector3(0, -0.9, 0);

(2) would look like this (you have to make the calling function async as well):

const res = await BABYLON.SceneLoader.ImportMeshAsync("hero", "./scenes/", "girl.glb", scene);

const hero = res.meshes[0];
hero.position = new BABYLON.Vector3(3.7,-5,-10);
hero.ellipsoid = new BABYLON.Vector3(0.5, 1.0, 0.5);
hero.ellipsoidOffset = new BABYLON.Vector3(0, 1.0, 0);

scene.gravity = new BABYLON.Vector3(0, -0.9, 0);

Not used the ImportMeshAsync API so my understanding of the object it resolves to may be slightly wrong. But the principle is correct.

1 Like
3

Thanks. I got the first method to work, if I made hero = null; in the main part and then put a condition to render it only if it wasn’t null in the render loop, otherwise I just got an error there. I’m going to check out the async also.