Cache renderables in SimpleScene into a vector

Set iteration is rather expensive, but I want to retain the O(logn)
performance of add and remove operations.

diff --git a/source/simplescene.cpp b/source/simplescene.cpp
index 73d08de2322f2194864490bf8b0bb7022678a654..4ccc714b79d7eefbe898a43677c0284a81e0a2ff 100644 (file)
--- a/source/simplescene.cpp
+++ b/source/simplescene.cpp
@@ -7,36 +7,49 @@ namespace GL {
 void SimpleScene::add(const Renderable &r)
 {
        renderables.insert(&r);
+       cache.clear();
 }
 
 void SimpleScene::remove(const Renderable &r)
 {
        renderables.erase(&r);
+       cache.clear();
+}
+
+void SimpleScene::populate_cache() const
+{
+       if(cache.empty() && !renderables.empty())
+       {
+               cache.reserve(renderables.size());
+               cache.insert(cache.end(), renderables.begin(), renderables.end());
+       }
 }
 
 void SimpleScene::setup_frame() const
 {
-       for(RenderableSet::const_iterator i=renderables.begin(); i!=renderables.end(); ++i)
+       populate_cache();
+       for(RenderableArray::const_iterator i=cache.begin(); i!=cache.end(); ++i)
                (*i)->setup_frame();
 }
 
 void SimpleScene::finish_frame() const
 {
-       for(RenderableSet::const_iterator i=renderables.begin(); i!=renderables.end(); ++i)
+       for(RenderableArray::const_iterator i=cache.begin(); i!=cache.end(); ++i)
                (*i)->finish_frame();
 }
 
 void SimpleScene::render(Renderer &renderer, const Tag &tag) const
 {
+       populate_cache();
        if(setup_frustum(renderer))
        {
-               for(RenderableSet::const_iterator i=renderables.begin(); i!=renderables.end(); ++i)
+               for(RenderableArray::const_iterator i=cache.begin(); i!=cache.end(); ++i)
                        if(!frustum_cull(**i))
                                renderer.render(**i, tag);
        }
        else
        {
-               for(RenderableSet::const_iterator i=renderables.begin(); i!=renderables.end(); ++i)
+               for(RenderableArray::const_iterator i=cache.begin(); i!=cache.end(); ++i)
                        renderer.render(**i, tag);
        }
 }

diff --git a/source/simplescene.h b/source/simplescene.h
index deba4d5f8877b872aa6d3be5dcc5cb7eecf7c0e1..ae7d169e408df3f790cd93f7daa3955b17f033cf 100644 (file)
--- a/source/simplescene.h
+++ b/source/simplescene.h
@@ -8,19 +8,25 @@ namespace Msp {
 namespace GL {
 
 /**
-The simplest possible Scene.  Rendering order is unspecified.
+A simple yet efficient scene.  Rendering order is unspecified.
 */
 class SimpleScene: public Scene
 {
 protected:
        typedef std::set<const Renderable *> RenderableSet;
+       typedef std::vector<const Renderable *> RenderableArray;
 
        RenderableSet renderables;
+       mutable RenderableArray cache;
 
 public:
        virtual void add(const Renderable &);
        virtual void remove(const Renderable &);
 
+private:
+       void populate_cache() const;
+
+public:
        virtual void setup_frame() const;
        virtual void finish_frame() const;