Further cleanup RenderPool

Ensure key is used correctly for `KeyedCollection`. Avoid changing types of variables to ensure readable code. Add some comments. Clean up renderer_limit example.

Author: vidartf

examples/renderer_limit.ipynb

@@ -25,12 +25,12 @@
     "mat5 = MeshStandardMaterial(color='#ff00ff')\n",
     "mat6 = MeshStandardMaterial(color='#00ffff')\n",
     "torus = TorusGeometry(radius=12, tube=3, radialSegments=16, tubularSegments=100)\n",
-    "mesh1 = Mesh(geometry=torus, material=mat1, _width=75, _height=75)\n",
-    "mesh2 = Mesh(geometry=torus, material=mat2, _width=75, _height=75)\n",
-    "mesh3 = Mesh(geometry=torus, material=mat3, _width=75, _height=75)\n",
-    "mesh4 = Mesh(geometry=torus, material=mat4, _width=75, _height=75)\n",
-    "mesh5 = Mesh(geometry=torus, material=mat5, _width=75, _height=75)\n",
-    "mesh6 = Mesh(geometry=torus, material=mat6, _width=75, _height=75)"
+    "mesh1 = Mesh(geometry=torus, material=mat1)\n",
+    "mesh2 = Mesh(geometry=torus, material=mat2)\n",
+    "mesh3 = Mesh(geometry=torus, material=mat3)\n",
+    "mesh4 = Mesh(geometry=torus, material=mat4)\n",
+    "mesh5 = Mesh(geometry=torus, material=mat5)\n",
+    "mesh6 = Mesh(geometry=torus, material=mat6)"
    ]
   },
   {

js/src/_base/RendererPool.js

@@ -84,11 +84,11 @@ _.extend(RendererPool.prototype, {
         return renderer;
     },
 
-    _replaceRenderer: function(renderer, config) {
-        var id = renderer.poolId;
-        renderer.dispose();
+    _replaceRenderer: function(oldToken, config) {
+        var id = oldToken.poolId;
+        oldToken.dispose();
         this.numCreated--;
-        renderer = this._createRenderer(config);
+        var renderer = this._createRenderer(config);
         renderer.poolId = id;
         return renderer;
     },
@@ -99,45 +99,48 @@ _.extend(RendererPool.prototype, {
         console.debug('RendererPool.acquiring...');
 
         if (this.freePool.length() > 0) {
-
-            renderer = this.freePool.pop(config);
-            if (renderer) {
-                renderer = renderer.renderer;
-            }
-            if (!renderer) {
-                var oldRenderer = this.freePool.shift();
-                renderer = this._replaceRenderer(oldRenderer, config);
+            // We have one or more free renderers
+            // (previously used renderers that have been released)
+
+            var freeToken = this.freePool.pop(config);
+            if (freeToken) {
+                // We have a free renderer with the correct config
+                renderer = freeToken.renderer;
+            } else {
+                // We need to replace one of the free renderers to get
+                // the right config:
+                freeToken = this.freePool.shift();
+                renderer = this._replaceRenderer(freeToken, config);
             }
 
         } else if (this.numCreated < MAX_RENDERERS) {
 
+            // We have not yet reached max capacity, create a new renderer:
             renderer = this._createRenderer(config);
 
         } else {
 
             // reclaim token
-            var claimedRenderer = this.claimedPool.pop(config);
-            var recreate = claimedRenderer === null;
+            var claimedToken = this.claimedPool.pop(config);
+            var recreate = claimedToken === null;
             if (recreate) {
-                claimedRenderer = this.claimedPool.shift();
+                claimedToken = this.claimedPool.shift();
             }
-            renderer = claimedRenderer.renderer;
+            renderer = claimedToken.renderer;
             try {
-                claimedRenderer.onReclaim();
+                claimedToken.onReclaim();
             } catch (e) {
                 // Ensure we do not lose the renderer:
-                this.freePool.push(renderer);
+                this.freePool.push(null, renderer);
                 throw e;
             }
             // Recreate renderer if no appropriate config:
             if (recreate) {
-                renderer = this._replaceRenderer(renderer, config);
+                renderer = this._replaceRenderer(claimedToken, config);
             }
 
         }
 
-        // Ensure aliasing state matches, or remake
-
         console.debug('RendererPool.acquire(id=' + renderer.poolId + ')');
         this.claimedPool.push(config, makeRendererClaimToken(renderer, onReclaim));
         renderer.clear();