Cache pickposition

CHANGES.md

@@ -7,6 +7,7 @@ Change Log
 * Fixed issue with displaying `MapboxImageryProvider` default token error message [#5191](https://github.com/AnalyticalGraphicsInc/cesium/pull/5191)
 * Added a `depthFailMaterial` property to line entities, which is the material used to render the line when it fails the depth test. [#5160](https://github.com/AnalyticalGraphicsInc/cesium/pull/5160)
 * Upgrade FXAA to version 3.11. [#5200](https://github.com/AnalyticalGraphicsInc/cesium/pull/5200)
+* `Scene.pickPosition` now caches results per frame to increase performance [#5117](https://github.com/AnalyticalGraphicsInc/cesium/issues/5117)
 * Fix billboards not initially clustering. [#5208](https://github.com/AnalyticalGraphicsInc/cesium/pull/5208)
 
 ### 1.32 - 2017-04-03

Source/Scene/Scene.js

@@ -321,6 +321,9 @@ define([
         this._cameraStartFired = false;
         this._cameraMovedTime = undefined;
 
+        this._pickPositionCache = {};
+        this._pickPositionCacheDirty = false;
+
         this._minimumDisableDepthTestDistance = 0.0;
 
         /**
@@ -2548,6 +2551,8 @@ define([
     var scratchEyeTranslation = new Cartesian3();
 
     function render(scene, time) {
+        scene._pickPositionCacheDirty = true;
+
         if (!defined(time)) {
             time = JulianDate.now();
         }
@@ -2979,6 +2984,15 @@ define([
         }
         //>>includeEnd('debug');
 
+        var cacheKey = windowPosition.toString();
+
+        if (this._pickPositionCacheDirty){
+            this._pickPositionCache = {};
+            this._pickPositionCacheDirty = false;
+        } else if (this._pickPositionCache.hasOwnProperty(cacheKey)){
+            return Cartesian3.clone(this._pickPositionCache[cacheKey], result);
+        }
+
         var context = this._context;
         var uniformState = context.uniformState;
 
@@ -3040,10 +3054,12 @@ define([
                     uniformState.update(this.frameState);
                 }
 
+                this._pickPositionCache[cacheKey] = Cartesian3.clone(result);
                 return result;
             }
         }
 
+        this._pickPositionCache[cacheKey] = undefined;
         return undefined;
     };
 
@@ -3078,6 +3094,7 @@ define([
             var cart = projection.unproject(result, scratchPickPositionCartographic);
             ellipsoid.cartographicToCartesian(cart, result);
         }
+
         return result;
     };
 

Specs/Scene/SceneSpec.js

@@ -33,6 +33,7 @@ defineSuite([
         'Scene/Scene',
         'Scene/ScreenSpaceCameraController',
         'Scene/TweenCollection',
+        'Scene/SceneTransforms',
         'Specs/createCanvas',
         'Specs/createScene',
         'Specs/equals',
@@ -72,6 +73,7 @@ defineSuite([
         Scene,
         ScreenSpaceCameraController,
         TweenCollection,
+        SceneTransforms,
         createCanvas,
         createScene,
         equals,
@@ -838,6 +840,41 @@ defineSuite([
         });
     });
 
+    it('pickPosition caches results per frame',function(){
+        if (!scene.pickPositionSupported) {
+            return;
+        }
+
+        var rectangle = Rectangle.fromDegrees(-100.0, 30.0, -90.0, 40.0);
+        scene.camera.setView({ destination : rectangle });
+
+        var canvas = scene.canvas;
+        var windowPosition = new Cartesian2(canvas.clientWidth / 2, canvas.clientHeight / 2);
+        spyOn(SceneTransforms, 'transformWindowToDrawingBuffer').and.callThrough();
+
+        expect(scene).toRenderAndCall(function() {
+            scene.pickPosition(windowPosition);
+            expect(SceneTransforms.transformWindowToDrawingBuffer).toHaveBeenCalled();
+
+            scene.pickPosition(windowPosition);
+            expect(SceneTransforms.transformWindowToDrawingBuffer.calls.count()).toEqual(1);
+
+            var rectanglePrimitive = createRectangle(rectangle);
+            rectanglePrimitive.appearance.material.uniforms.color = new Color(1.0, 0.0, 0.0, 1.0);
+
+            var primitives = scene.primitives;
+            primitives.add(rectanglePrimitive);
+        });
+
+        expect(scene).toRenderAndCall(function() {
+            scene.pickPosition(windowPosition);
+            expect(SceneTransforms.transformWindowToDrawingBuffer.calls.count()).toEqual(2);
+
+            scene.pickPosition(windowPosition);
+            expect(SceneTransforms.transformWindowToDrawingBuffer.calls.count()).toEqual(2);
+        });
+    });
+
     it('pickPosition throws without windowPosition', function() {
         expect(function() {
             scene.pickPosition();