Freestyle: View map caching.

New render layer option named "View map cache" is added to reuse a
previously computed view map for subsequent rendering.  The cache is
automatically updated when the mesh geometry of the input 3D scene has
been changed.

This functionality offers a major performance boost for Freestyle
animation rendering when camera-space mesh geometry is static, as well
as for repeated still renders with updates of line stylization options.

Although the "View map cache" toggle is a render layer option, the cache
memory is shared by all render layers and scenes.  This means that if
Freestyle is used for two or more render layers (possibly in different
scenes through the compositor), then the cached view map for one render
layer is replaced by a new view map for another render layer and hence
no performance gain is expected.

2 files changed, 56 insertions, 38 deletions

diff --git a/source/blender/freestyle/intern/application/Controller.cpp b/source/blender/freestyle/intern/application/Controller.cpp
index 176199600ac..a7f936ff171 100644
--- a/source/blender/freestyle/intern/application/Controller.cpp
+++ b/source/blender/freestyle/intern/application/Controller.cpp
@@ -118,6 +118,7 @@ Controller::Controller()
 	_Canvas = new AppCanvas;
 
 	_inter = new PythonInterpreter();
+	_EnableViewMapCache = false;
 	_EnableQI = true;
 	_EnableFaceSmoothness = false;
 	_ComputeRidges = true;
@@ -212,6 +213,19 @@ void Controller::setContext(bContext *C)
 	py_inter->setContext(C);
 }
 
+bool Controller::hitViewMapCache()
+{
+	if (!_EnableViewMapCache) {
+		return false;
+	}
+	real hashCode = sceneHashFunc.getValue();
+	if (prevSceneHash == hashCode) {
+		return (NULL != _ViewMap);
+	}
+	prevSceneHash = hashCode;
+	return false;
+}
+
 int Controller::LoadMesh(Render *re, SceneRenderLayer *srl)
 {
 	BlenderFileLoader loader(re, srl);
@@ -242,6 +256,7 @@ int Controller::LoadMesh(Render *re, SceneRenderLayer *srl)
 	if (G.debug & G_DEBUG_FREESTYLE) {
 		cout << "Scene loaded" << endl;
 		printf("Mesh cleaning    : %lf\n", duration);
+		printf("View map cache   : %s\n", _EnableViewMapCache ? "enabled" : "disabled");
 	}
 	_SceneNumFaces += loader.numFacesRead();
 
@@ -263,6 +278,22 @@ int Controller::LoadMesh(Render *re, SceneRenderLayer *srl)
 	if (_pRenderMonitor->testBreak())
 		return 0;
 
+	if (_EnableViewMapCache) {
+		sceneHashFunc.reset();
+		blenderScene->accept(sceneHashFunc);
+		if (G.debug & G_DEBUG_FREESTYLE) {
+			printf("Scene hash       : %.16e\n", sceneHashFunc.getValue());
+		}
+		if (hitViewMapCache()) {
+			ClearRootNode();
+			return 0;
+		}
+		else {
+			delete _ViewMap;
+			_ViewMap = NULL;
+		}
+	}
+
 	_Chrono.start();
 
 	WXEdgeBuilder wx_builder;
@@ -357,7 +388,7 @@ void Controller::DeleteWingedEdge()
 	_minEdgeSize = DBL_MAX;
 }
 
-void Controller::DeleteViewMap()
+void Controller::DeleteViewMap(bool freeCache)
 {
 	_pView->DetachSilhouette();
 	if (NULL != _SilhouetteNode) {
@@ -387,14 +418,15 @@ void Controller::DeleteViewMap()
 
 	_pView->DetachDebug();
 	if (NULL != _DebugNode) {
-	int ref = _DebugNode->destroy();
+		int ref = _DebugNode->destroy();
 		if (0 == ref)
 			_DebugNode->addRef();
 	}
 
-	if (NULL != _ViewMap) {
+	if ((freeCache || !_EnableViewMapCache) && NULL != _ViewMap) {
 		delete _ViewMap;
 		_ViewMap = NULL;
+		prevSceneHash = -1.0;
 	}
 }
 
@@ -403,40 +435,7 @@ void Controller::ComputeViewMap()
 	if (!_ListOfModels.size())
 		return;
 
-	if (NULL != _ViewMap) {
-		delete _ViewMap;
-		_ViewMap = NULL;
-	}
-
-	_pView->DetachDebug();
-	if (NULL != _DebugNode) {
-		int ref = _DebugNode->destroy();
-		if (0 == ref)
-			_DebugNode->addRef();
-	}
-
-	_pView->DetachSilhouette();
-	if (NULL != _SilhouetteNode) {
-		int ref = _SilhouetteNode->destroy();
-		if (0 == ref)
-			delete _SilhouetteNode;
-	}
-
-#if 0
-	if (NULL != _ProjectedSilhouette) {
-		int ref = _ProjectedSilhouette->destroy();
-		if (0 == ref)
-			delete _ProjectedSilhouette;
-	}
-
-	if (NULL != _VisibleProjectedSilhouette) {
-		int ref = _VisibleProjectedSilhouette->destroy();
-		if (0 == ref) {
-			delete _VisibleProjectedSilhouette;
-			_VisibleProjectedSilhouette = NULL;
-		}
-	}
-#endif
+	DeleteViewMap(true);
 
 	// retrieve the 3D viewpoint and transformations information
 	//----------------------------------------------------------
@@ -763,6 +762,16 @@ int Controller::getVisibilityAlgo()
 	return FREESTYLE_ALGO_ADAPTIVE_TRADITIONAL;
 }
 
+void Controller::setViewMapCache(bool iBool)
+{
+	_EnableViewMapCache = iBool;
+}
+
+bool Controller::getViewMapCache() const
+{
+	return _EnableViewMapCache;
+}
+
 void Controller::setQuantitativeInvisibility(bool iBool)
 {
 	_EnableQI = iBool;
diff --git a/source/blender/freestyle/intern/application/Controller.h b/source/blender/freestyle/intern/application/Controller.h
index f5e50347d0f..84ee3382612 100644
--- a/source/blender/freestyle/intern/application/Controller.h
+++ b/source/blender/freestyle/intern/application/Controller.h
@@ -32,6 +32,7 @@
 
 //#include "ConfigIO.h"
 #include "../geometry/FastGrid.h"
+#include "../scene_graph/SceneHash.h"
 #include "../system/Interpreter.h"
 #include "../system/ProgressBar.h"
 #include "../system/Precision.h"
@@ -96,7 +97,7 @@ public:
 	void Clear();
 	void ClearRootNode();
 	void DeleteWingedEdge();
-	void DeleteViewMap();
+	void DeleteViewMap(bool freeCache = false);
 	void toggleLayer(unsigned index, bool iDisplay);
 	void setModified(unsigned index, bool iMod);
 	void resetModified(bool iMod=false);
@@ -118,6 +119,8 @@ public:
 	void setVisibilityAlgo(int algo);
 	int getVisibilityAlgo();
 
+	void setViewMapCache(bool iBool);
+	bool getViewMapCache() const;
 	void setQuantitativeInvisibility(bool iBool); // if true, we compute quantitativeInvisibility
 	bool getQuantitativeInvisibility() const;
 	void setFaceSmoothness(bool iBool);
@@ -144,6 +147,8 @@ public:
 	void setModulesDir(const string& dir);
 	string getModulesDir() const;
 
+	bool hitViewMapCache();
+
 	void resetInterpreter();
 
 public:
@@ -231,6 +236,7 @@ private:
 	string _help_index;
 	string _browser_cmd;
 
+	bool _EnableViewMapCache;
 	bool _EnableQI;
 	bool _EnableFaceSmoothness;
 	bool _ComputeRidges;
@@ -244,6 +250,9 @@ private:
 
 	FEdgeXDetector edgeDetector;
 
+	SceneHash sceneHashFunc;
+	real prevSceneHash = -1.0;
+
 #ifdef WITH_CXX_GUARDEDALLOC
 	MEM_CXX_CLASS_ALLOC_FUNCS("Freestyle:Controller")
 #endif