Track the number of tiles loading since loading had finished previously (#920)

* Track the number of tiles loading since loading had finished previously

* Update names

* Add "loadPercent"

* loadPercent -> loadProgress

Author: gkjohnson

README.md

@@ -392,14 +392,6 @@ If true then the `raycast` functions of the loaded tile objects are overriden to
 
 If you would like to manage raycasting against tiles yourself this behavior can be disabled if needed by setting `optizeRaycast` to false.
 
-### .preprocessURL
-
-```js
-preprocessURL = null : ( uri : string | URL ) => string | URL;
-```
-
-Function to preprocess the url for each individual tile geometry or child tile set to be loaded. If null then the url is used directly.
-
 ### .lruCache
 
 ```js
@@ -446,6 +438,14 @@ manager : LoadingManager
 
 The manager used when loading tile geometry.
 
+### .loadProgress
+
+```js
+readOnly loadProgress : Number
+```
+
+Returns the total load progress between `[0, 1]`. Progress is measured since the last set of loading tiles completed.
+
 ### .constructor
 
 ```js

src/base/TilesRendererBase.js

@@ -87,15 +87,12 @@ export class TilesRendererBase {
 
 	}
 
-	set loadSiblings( v ) {
+	get loadProgress() {
 
-		console.warn( 'TilesRenderer: "loadSiblings" option has been removed.' );
-
-	}
-
-	set stopAtEmptyTiles( v ) {
-
-		console.warn( 'TilesRenderer: "stopAtEmptyTiles" option has been removed.' );
+		const stats = this.stats;
+		const loading = stats.downloading + stats.parsing;
+		const total = stats.inCacheSinceLoad;
+		return total === 0 ? 1.0 : 1.0 - loading / total;
 
 	}
 
@@ -108,6 +105,7 @@ export class TilesRendererBase {
 		this.fetchOptions = {};
 		this.plugins = [];
 		this.queuedTiles = [];
+		this.cachedSinceLoadComplete = new Set();
 
 		const lruCache = new LRUCache();
 		lruCache.unloadPriorityCallback = lruPriorityCallback;
@@ -125,6 +123,7 @@ export class TilesRendererBase {
 		this.downloadQueue = downloadQueue;
 		this.parseQueue = parseQueue;
 		this.stats = {
+			inCacheSinceLoad: 0,
 			inCache: 0,
 			parsing: 0,
 			downloading: 0,
@@ -642,6 +641,13 @@ export class TilesRendererBase {
 
 			// Decrement stats
 			stats.inCache --;
+			if ( this.cachedSinceLoadComplete.has( tile ) ) {
+
+				this.cachedSinceLoadComplete.delete( tile );
+				stats.inCacheSinceLoad --;
+
+			}
+
 			if ( t.__loadingState === LOADING ) {
 
 				stats.downloading --;
@@ -666,6 +672,8 @@ export class TilesRendererBase {
 
 		}
 
+		this.cachedSinceLoadComplete.add( tile );
+		stats.inCacheSinceLoad ++;
 		stats.inCache ++;
 		stats.downloading ++;
 		tile.__loadingState = LOADING;
@@ -809,6 +817,16 @@ export class TilesRendererBase {
 
 				}
 
+			} )
+			.finally( () => {
+
+				if ( stats.parsing === 0 && stats.downloading === 0 ) {
+
+					this.cachedSinceLoadComplete.clear();
+					stats.inCacheSinceLoad = 0;
+
+				}
+
 			} );
 
 	}