From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 12 Jan 2011 19:54:13 +0000 (+0000)
Subject: Generalize instancing to all Renderables
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=0e8ffd3b59e9b5c52c66c22c9ae4f9d3544aa6bf

Generalize instancing to all Renderables
---

diff --git a/source/instancescene.cpp b/source/instancescene.cpp
index adaebbba..fb99dda8 100644
--- a/source/instancescene.cpp
+++ b/source/instancescene.cpp
@@ -15,37 +15,25 @@ namespace GL {
 
 void InstanceScene::add(const Renderable &r)
 {
-	if(const ObjectInstance *oi = dynamic_cast<const ObjectInstance *>(&r))
-		objects[&oi->get_object()].insert(oi);
-	else
-		renderables.insert(&r);
+	renderables[r.get_instance_key()].insert(&r);
 }
 
 void InstanceScene::remove(const Renderable &r)
 {
-	if(const ObjectInstance *oi = dynamic_cast<const ObjectInstance *>(&r))
+	InstanceMap::iterator i = renderables.find(r.get_instance_key());
+	if(i!=renderables.end())
 	{
-		ObjectMap::iterator i = objects.find(&oi->get_object());
-		if(i!=objects.end())
-		{
-			i->second.erase(oi);
-			if(i->second.empty())
-				objects.erase(i);
-		}
+		i->second.erase(&r);
+		if(i->second.empty())
+			renderables.erase(i);
 	}
-	else
-		renderables.erase(&r);
 }
 
 void InstanceScene::render(Renderer &renderer, const Tag &tag) const
 {
-	// XXX Check that the object has this pass to avoid some unnecessary function calls
-	for(ObjectMap::const_iterator i=objects.begin(); i!=objects.end(); ++i)
-		for(InstanceSet::const_iterator j=i->second.begin(); j!=i->second.end(); ++j)
+	for(InstanceMap::const_iterator i=renderables.begin(); i!=renderables.end(); ++i)
+		for(RenderableSet::const_iterator j=i->second.begin(); j!=i->second.end(); ++j)
 			(*j)->render(renderer, tag);
-
-	for(RenderableSet::const_iterator i=renderables.begin(); i!=renderables.end(); ++i)
-		(*i)->render(renderer, tag);
 }
 
 } // namespace GL
diff --git a/source/instancescene.h b/source/instancescene.h
index 55bd266d..18229d72 100644
--- a/source/instancescene.h
+++ b/source/instancescene.h
@@ -15,22 +15,18 @@ Distributed under the LGPL
 namespace Msp {
 namespace GL {
 
-class Object;
-class ObjectInstance;
-
 /**
-A Scene optimized for rendering ObjectInstances.  All instances of the same
-Object are rendered in one go; otherwise the rendering order is unspecified.
+A Scene optimized for rendering instanced Renderables, such as ObjectInstances.
+All Renderables with the same instance key are rendered consecutively; within
+the same key rendering order is unspecified.
 */
 class InstanceScene: public Scene
 {
 private:
-	typedef std::set<const ObjectInstance *> InstanceSet;
-	typedef std::map<const Object *, InstanceSet> ObjectMap;
 	typedef std::set<const Renderable *> RenderableSet;
+	typedef std::map<long, RenderableSet> InstanceMap;
 
-	ObjectMap objects;
-	RenderableSet renderables;
+	InstanceMap renderables;
 
 public:
 	virtual void add(const Renderable &);
diff --git a/source/objectinstance.h b/source/objectinstance.h
index d665851f..e7f85e3f 100644
--- a/source/objectinstance.h
+++ b/source/objectinstance.h
@@ -31,6 +31,7 @@ public:
 	ObjectInstance(const Object &);
 
 	const Object &get_object() const { return object; }
+	virtual long get_instance_key() const { return reinterpret_cast<long>(&object); }
 
 	virtual void render(const Tag &tag = Tag()) const;
 	virtual void render(Renderer &, const Tag & = Tag()) const;
diff --git a/source/renderable.h b/source/renderable.h
index 8e31d5a7..9fe46956 100644
--- a/source/renderable.h
+++ b/source/renderable.h
@@ -23,6 +23,9 @@ protected:
 public:
 	virtual ~Renderable() { }
 
+	/** Returns a key used for grouping Renderables in an InstanceScene. */
+	virtual long get_instance_key() const { return 0; }
+
 	virtual void render(const Tag & = Tag()) const;
 	virtual void render(Renderer &, const Tag & = Tag()) const;
 };