Texture as a Promise

Description of the problem

Loading textures with TextureLoader.load is great for as long as someone stays strictly within ThreeJS env (since needsUpdate does all the work.)

When trying to go “outside” of three, for example “change this icon, when texture is loaded” it becomes a bit … dated. Loader allows only for onLoad callbacks, which are ok only for as long as you care about a single texture. When you want to “change this icon, when these 3 textures are loaded”, there are two options:

• chain onLoad callbacks (bad)
• wrap each load in a Promise manually, and .all(...) them (better)

Would be very nice to have this Promise functionality out of the box (this also makes async / await, which improves readability significantly.)

I can see 1 or 2 nice improvements that could help there:

• (1) Add .promise(url) method to TextureLoader, that instead of Texture returns a Promise (not ideal, but already better, if you care more about loading.)

const textureLoader = new Three.TextureLoader();

Promise.all([
  textureLoader.promise(url1), // new Promise instead of new Texture
  textureLoader.promise(url2),
  textureLoader.promise(url3)
])
.then((textures) => {
   // ...
});

Obvious con here is that .promise() can’t nicely return both texture and a promise… unless!

• (2) Add PromisedTexture wrapper extending Texture, that would add Promise proto functionality (similarly as CanvasTexture does with canvas.) Promised texture would resolve/reject after initially loading, allowing for handling the async process manually outside of ThreeJS.

const textureLoader = new Three.TextureLoader();

const texture1 = textureLoader.promise(url1); // new PromiseTexture
const texture2 = textureLoader.promise(url2); 
const texture3 = textureLoader.promise(url3); 

Promise.all([ texture1, texture2, texture3 ])
.then((textures) => {
   // ...
});

Three.js version

Latest

Browser

N/A

OS

N/A

Hardware Requirements (graphics card, VR Device, …)

N/A

[mrdoob]

How about Loader.prototype.loadAsync?

[mrdoob]

If we did this we would have to change all the loaders in the lib. I think it may be easier to make an abstraction in your project.