[v9] fix(useLoader): localize url caching per loader

packages/fiber/src/core/hooks.tsx

@@ -91,15 +91,15 @@ export type LoaderResult<T> = T extends { scene: THREE.Object3D } ? T & ObjectMa
 export type Extensions<T> = (loader: Loader<T>) => void
 
 const memoizedLoaders = new WeakMap<LoaderProto<any>, Loader<any>>()
+const memoizedResults = new WeakMap<Loader<unknown>, Map<string, Promise<unknown>>>()
 
 const isConstructor = <T,>(value: unknown): value is LoaderProto<T> =>
  typeof value === 'function' && value?.prototype?.constructor === value
 
 function loadingFn<T>(extensions?: Extensions<T>, onProgress?: (event: ProgressEvent) => void) {
- return async function (Proto: Loader<T> | LoaderProto<T>, ...input: string[]) {
- let loader: Loader<any>
-
+ return async function (Proto: Loader<T> | LoaderProto<T>, ...urls: string[]) {
  // Construct and cache loader if constructor was passed
+ let loader!: Loader<T>
  if (isConstructor(Proto)) {
  loader = memoizedLoaders.get(Proto)!
  if (!loader) {
@@ -110,22 +110,37 @@ function loadingFn<T>(extensions?: Extensions<T>, onProgress?: (event: ProgressE
  loader = Proto
  }
 
+ // Prime per-loader cache
+ let results: Map<string, Promise<unknown>> = memoizedResults.get(loader)!
+ if (!results) {
+ results = new Map()
+ memoizedResults.set(loader, results)
+ }
+
  // Apply loader extensions
  if (extensions) extensions(loader)
 
  // Go through the urls and load them
  return Promise.all(
- input.map(
- (input) =>
- new Promise<LoaderResult<T>>((res, reject) =>
- loader.load(
- input,
- (data) => res(isObject3D(data?.scene) ? Object.assign(data, buildGraph(data.scene)) : data),
- onProgress,
- (error) => reject(new Error(`Could not load ${input}: ${(error as ErrorEvent)?.message}`)),
- ),
- ),
- ),
+ urls.map((url) => {
+ // Load url and cache the result on first try
+ if (!results.has(url)) {
+ try {
+ results.set(
+ url,
+ loader
+ .loadAsync(url, onProgress)
+ .then((data) => (isObject3D(data?.scene) ? Object.assign(data, buildGraph(data.scene)) : data)),
+ )
+ } catch (error) {
+ // TODO: merge errors for multiple urls
+ throw new Error(`Could not load ${url}: ${(error as ErrorEvent)?.message}`)
+ }
+ }
+
+ // Return cached pending or completed result
+ return results.get(url)
+ }),
  )
  }
 }