add emtpy parcels to worlds (#6087)

Author: gonpombo8

browser-interface/packages/shared/scene-loader/world-loader-impl/index.ts

@@ -1,14 +1,54 @@
 import { getPortableExperienceFromUrn } from 'unity-interface/portableExperiencesUtils'
 import { ISceneLoader } from '../types'
+import { encodeParcelPosition } from '../../../lib/decentraland'
+import { Vector2 } from '@dcl/ecs-math'
+import { getResourcesURL } from '../../location'
+import { EmptyParcelController } from '../genesis-city-loader-impl/emptyParcelController'
+import { LoadableScene } from '../../types'
+
+function getParcels(position: Vector2, loadingRadius: number): string[] {
+  const parcels: string[] = []
+  for (let x = position.x - loadingRadius; x < position.x + loadingRadius; x++) {
+    for (let y = position.y - loadingRadius; y < position.y + loadingRadius; y++) {
+      const v = new Vector2(x, y)
+      if (v.subtract(position).length() < loadingRadius) {
+        parcels.push(encodeParcelPosition(v))
+      }
+    }
+  }
+  return parcels
+}
 
 export async function createWorldLoader(options: { urns: string[] }): Promise<ISceneLoader> {
+  const mappingScene = new Map<string, LoadableScene>()
   const scenes = await Promise.all(options.urns.map((urn) => getPortableExperienceFromUrn(urn)))
+
+  for (const parcel of scenes[0].entity.metadata.scene.parcels) {
+    mappingScene.set(parcel, scenes[0])
+  }
+
+  const emptyParcelController = new EmptyParcelController({ rootUrl: getResourcesURL('.') })
+
   return {
     async fetchScenesByLocation(_parcels) {
       return { scenes }
     },
-    async reportPosition(_positionReport) {
-      return { scenes }
+    async reportPosition(positionReport) {
+      const newScenes: Set<LoadableScene> = new Set()
+      for await (const parcel of getParcels(
+        new Vector2(positionReport.position.x, positionReport.position.y),
+        positionReport.loadingRadius
+      )) {
+        if (mappingScene.has(parcel)) {
+          newScenes.add(mappingScene.get(parcel)!)
+        } else {
+          const scene = await emptyParcelController.createFakeEntity(parcel)
+
+          mappingScene.set(parcel, scene)
+          newScenes.add(scene)
+        }
+      }
+      return { scenes: Array.from(newScenes) }
     },
     async stop() {},
     invalidateCache(_) {}