Babylon.js/src/Rendering/babylon.utilityLayerRenderer.ts

module BABYLON {
    /**
     * Renders a layer on top of an existing scene
     */
    export class UtilityLayerRenderer implements IDisposable {
        private _pointerCaptures: { [pointerId: number]: boolean } = {};
        private _lastPointerEvents: { [pointerId: number]: boolean } = {};
        private static _DefaultUtilityLayer: Nullable<UtilityLayerRenderer> = null;
        private static _DefaultKeepDepthUtilityLayer: Nullable<UtilityLayerRenderer> = null;

        /**
         * If the picking should be done on the utility layer prior to the actual scene (Default: true)
         */
        public pickUtilitySceneFirst = true;
        /**
         * A shared utility layer that can be used to overlay objects into a scene (Depth map of the previous scene is cleared before drawing on top of it)
         */
        public static get DefaultUtilityLayer(): UtilityLayerRenderer {
            if (UtilityLayerRenderer._DefaultUtilityLayer == null) {
                UtilityLayerRenderer._DefaultUtilityLayer = new UtilityLayerRenderer(BABYLON.Engine.LastCreatedScene!);
                UtilityLayerRenderer._DefaultUtilityLayer.originalScene.onDisposeObservable.addOnce(() => {
                    UtilityLayerRenderer._DefaultUtilityLayer = null;
                });
            }
            return UtilityLayerRenderer._DefaultUtilityLayer;
        }
        /**
         * A shared utility layer that can be used to embed objects into a scene (Depth map of the previous scene is not cleared before drawing on top of it)
         */
        public static get DefaultKeepDepthUtilityLayer(): UtilityLayerRenderer {
            if (UtilityLayerRenderer._DefaultKeepDepthUtilityLayer == null) {
                UtilityLayerRenderer._DefaultKeepDepthUtilityLayer = new UtilityLayerRenderer(BABYLON.Engine.LastCreatedScene!);
                UtilityLayerRenderer._DefaultKeepDepthUtilityLayer.utilityLayerScene.autoClearDepthAndStencil = false;
                UtilityLayerRenderer._DefaultKeepDepthUtilityLayer.originalScene.onDisposeObservable.addOnce(() => {
                    UtilityLayerRenderer._DefaultKeepDepthUtilityLayer = null;
                });
            }
            return UtilityLayerRenderer._DefaultKeepDepthUtilityLayer;
        }

        /**
         * The scene that is rendered on top of the original scene
         */
        public utilityLayerScene: Scene;

        /**
         *  If the utility layer should automatically be rendered on top of existing scene
        */
        public shouldRender: boolean = true;
        /**
         * If set to true, only pointer down onPointerObservable events will be blocked when picking is occluded by original scene
         */
        public onlyCheckPointerDownEvents = true;

        /**
         * If set to false, only pointerUp, pointerDown and pointerMove will be sent to the utilityLayerScene (false by default)
         */
        public processAllEvents = false;

        /**
         * Observable raised when the pointer move from the utility layer scene to the main scene
         */
        public onPointerOutObservable = new Observable<number>();

        /** Gets or sets a predicate that will be used to indicate utility meshes present in the main scene */
        public mainSceneTrackerPredicate: (mesh: Nullable<AbstractMesh>) => boolean;

        private _afterRenderObserver: Nullable<Observer<Scene>>;
        private _sceneDisposeObserver: Nullable<Observer<Scene>>;
        private _originalPointerObserver: Nullable<Observer<PointerInfoPre>>;
        /**
         * Instantiates a UtilityLayerRenderer
         * @param originalScene the original scene that will be rendered on top of
         */
        constructor(
            /** the original scene that will be rendered on top of */
            public originalScene: Scene) {
            // Create scene which will be rendered in the foreground and remove it from being referenced by engine to avoid interfering with existing app
            this.utilityLayerScene = new BABYLON.Scene(originalScene.getEngine());
            this.utilityLayerScene.useRightHandedSystem = originalScene.useRightHandedSystem;
            this.utilityLayerScene._allowPostProcessClearColor = false;
            originalScene.getEngine().scenes.pop();

            // Detach controls on utility scene, events will be fired by logic below to handle picking priority
            this.utilityLayerScene.detachControl();
            this._originalPointerObserver = originalScene.onPrePointerObservable.add((prePointerInfo, eventState) => {

                if (!this.processAllEvents) {
                    if (prePointerInfo.type !== BABYLON.PointerEventTypes.POINTERMOVE
                        && prePointerInfo.type !== BABYLON.PointerEventTypes.POINTERUP
                        && prePointerInfo.type !== BABYLON.PointerEventTypes.POINTERDOWN) {
                        return;
                    }
                }

                let pointerEvent = <PointerEvent>(prePointerInfo.event);
                if (originalScene!.isPointerCaptured(pointerEvent.pointerId)) {
                    this._pointerCaptures[pointerEvent.pointerId] = false;
                    return;
                }

                var utilityScenePick = prePointerInfo.ray ? this.utilityLayerScene.pickWithRay(prePointerInfo.ray) : this.utilityLayerScene.pick(originalScene.pointerX, originalScene.pointerY);
                if (!prePointerInfo.ray && utilityScenePick) {
                    prePointerInfo.ray = utilityScenePick.ray;
                }

                // always fire the prepointer oversvable
                this.utilityLayerScene.onPrePointerObservable.notifyObservers(prePointerInfo);

                // allow every non pointer down event to flow to the utility layer
                if (this.onlyCheckPointerDownEvents && prePointerInfo.type != BABYLON.PointerEventTypes.POINTERDOWN) {
                    if (!prePointerInfo.skipOnPointerObservable) {
                        this.utilityLayerScene.onPointerObservable.notifyObservers(new PointerInfo(prePointerInfo.type, prePointerInfo.event, utilityScenePick));
                    }
                    if (prePointerInfo.type === BABYLON.PointerEventTypes.POINTERUP && this._pointerCaptures[pointerEvent.pointerId]) {
                        this._pointerCaptures[pointerEvent.pointerId] = false;
                    }
                    return;
                }

                if (this.utilityLayerScene.autoClearDepthAndStencil || this.pickUtilitySceneFirst) {
                    // If this layer is an overlay, check if this layer was hit and if so, skip pointer events for the main scene
                    if (utilityScenePick && utilityScenePick.hit) {

                        if (!prePointerInfo.skipOnPointerObservable) {
                            this.utilityLayerScene.onPointerObservable.notifyObservers(new PointerInfo(prePointerInfo.type, prePointerInfo.event, utilityScenePick));
                        }
                        prePointerInfo.skipOnPointerObservable = true;
                    }
                } else {
                    var originalScenePick = prePointerInfo.ray ? originalScene.pickWithRay(prePointerInfo.ray) : originalScene.pick(originalScene.pointerX, originalScene.pointerY);
                    let pointerEvent = <PointerEvent>(prePointerInfo.event);

                    // If the layer can be occluded by the original scene, only fire pointer events to the first layer that hit they ray
                    if (originalScenePick && utilityScenePick) {

                        // No pick in utility scene
                        if (utilityScenePick.distance === 0 && originalScenePick.pickedMesh) {
                            if (this.mainSceneTrackerPredicate && this.mainSceneTrackerPredicate(originalScenePick.pickedMesh)) {
                                // We touched an utility mesh present in the main scene
                                this._notifyObservers(prePointerInfo, originalScenePick, pointerEvent);
                                prePointerInfo.skipOnPointerObservable = true;
                            } else if (prePointerInfo.type === BABYLON.PointerEventTypes.POINTERDOWN) {
                                this._pointerCaptures[pointerEvent.pointerId] = true;
                            } else if (this._lastPointerEvents[pointerEvent.pointerId]) {
                                // We need to send a last pointerup to the utilityLayerScene to make sure animations can complete
                                this.onPointerOutObservable.notifyObservers(pointerEvent.pointerId);
                                delete this._lastPointerEvents[pointerEvent.pointerId];
                            }
                        } else if (!this._pointerCaptures[pointerEvent.pointerId] && (utilityScenePick.distance < originalScenePick.distance || originalScenePick.distance === 0)) {
                            // We pick something in utility scene or the pick in utility is closer than the one in main scene
                            this._notifyObservers(prePointerInfo, utilityScenePick, pointerEvent);
                            // If a previous utility layer set this, do not unset this
                            if (!prePointerInfo.skipOnPointerObservable) {
                                prePointerInfo.skipOnPointerObservable = utilityScenePick.distance > 0;
                            }
                        } else if (!this._pointerCaptures[pointerEvent.pointerId] && (utilityScenePick.distance > originalScenePick.distance)) {
                            // We have a pick in both scenes but main is closer than utility

                            // We touched an utility mesh present in the main scene
                            if (this.mainSceneTrackerPredicate && this.mainSceneTrackerPredicate(originalScenePick.pickedMesh)) {
                                this._notifyObservers(prePointerInfo, originalScenePick, pointerEvent);
                                prePointerInfo.skipOnPointerObservable = true;
                            } else if (this._lastPointerEvents[pointerEvent.pointerId]) {
                                // We need to send a last pointerup to the utilityLayerScene to make sure animations can complete
                                this.onPointerOutObservable.notifyObservers(pointerEvent.pointerId);
                                delete this._lastPointerEvents[pointerEvent.pointerId];
                            }
                        }

                        if (prePointerInfo.type === BABYLON.PointerEventTypes.POINTERUP && this._pointerCaptures[pointerEvent.pointerId]) {
                            this._pointerCaptures[pointerEvent.pointerId] = false;
                        }
                    }
                }

            });

            // Render directly on top of existing scene without clearing
            this.utilityLayerScene.autoClear = false;

            this._afterRenderObserver = this.originalScene.onAfterRenderObservable.add(() => {
                if (this.shouldRender) {
                    this.render();
                }
            });

            this._sceneDisposeObserver = this.originalScene.onDisposeObservable.add(() => {
                this.dispose();
            });

            this._updateCamera();
        }

        private _notifyObservers(prePointerInfo: PointerInfoPre, pickInfo: PickingInfo, pointerEvent: PointerEvent) {
            if (!prePointerInfo.skipOnPointerObservable) {
                this.utilityLayerScene.onPointerObservable.notifyObservers(new PointerInfo(prePointerInfo.type, prePointerInfo.event, pickInfo));
                this._lastPointerEvents[pointerEvent.pointerId] = true;
            }
        }

        /**
         * Renders the utility layers scene on top of the original scene
         */
        public render() {
            this._updateCamera();
            if (this.utilityLayerScene.activeCamera) {
                // Set the camera's scene to utility layers scene
                var oldScene = this.utilityLayerScene.activeCamera.getScene();
                var camera = this.utilityLayerScene.activeCamera;
                camera._scene = this.utilityLayerScene;
                if (camera.leftCamera) {
                    camera.leftCamera._scene = this.utilityLayerScene;
                }
                if (camera.rightCamera) {
                    camera.rightCamera._scene = this.utilityLayerScene;
                }

                this.utilityLayerScene.render(false);

                // Reset camera's scene back to original
                camera._scene = oldScene;
                if (camera.leftCamera) {
                    camera.leftCamera._scene = oldScene;
                }
                if (camera.rightCamera) {
                    camera.rightCamera._scene = oldScene;
                }
            }

        }

        /**
         * Disposes of the renderer
         */
        public dispose() {
            this.onPointerOutObservable.clear();

            if (this._afterRenderObserver) {
                this.originalScene.onAfterRenderObservable.remove(this._afterRenderObserver);
            }
            if (this._sceneDisposeObserver) {
                this.originalScene.onDisposeObservable.remove(this._sceneDisposeObserver);
            }
            if (this._originalPointerObserver) {
                this.originalScene.onPrePointerObservable.remove(this._originalPointerObserver);
            }
            this.utilityLayerScene.dispose();
        }

        private _updateCamera() {
            this.utilityLayerScene.activeCamera = this.originalScene.activeCamera;
        }
    }
}