From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 21 Sep 2013 09:59:22 +0000 (+0300)
Subject: Add a Scene type that sorts its renderables by depth
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=c87860db3b23a98eda1adfe59acddffdb6eb8420

Add a Scene type that sorts its renderables by depth
---

diff --git a/source/scene.h b/source/scene.h
index e3aa1fab..fbc57a80 100644
--- a/source/scene.h
+++ b/source/scene.h
@@ -10,7 +10,7 @@ class Culler;
 
 /**
 Scenes are containers for other Renderables.  This is a base class that can't
-be instantiated.  At the moment the available Scene types are SimpleScene,
+be instantiated.  Examples of available Scene types are SimpleScene,
 InstancedScene and OrderedScene.
 */
 class Scene: public Renderable
diff --git a/source/simplescene.h b/source/simplescene.h
index be86285b..deba4d5f 100644
--- a/source/simplescene.h
+++ b/source/simplescene.h
@@ -12,7 +12,7 @@ The simplest possible Scene.  Rendering order is unspecified.
 */
 class SimpleScene: public Scene
 {
-private:
+protected:
 	typedef std::set<const Renderable *> RenderableSet;
 
 	RenderableSet renderables;
diff --git a/source/zsortedscene.cpp b/source/zsortedscene.cpp
new file mode 100644
index 00000000..da406b7e
--- /dev/null
+++ b/source/zsortedscene.cpp
@@ -0,0 +1,67 @@
+#include "camera.h"
+#include "renderer.h"
+#include "zsortedscene.h"
+
+using namespace std;
+
+namespace Msp {
+namespace GL {
+
+ZSortedScene::ZSortedScene():
+	order(BACK_TO_FRONT),
+	reference(FURTHEST)
+{ }
+
+void ZSortedScene::set_order(SortOrder o)
+{
+	order = o;
+}
+
+void ZSortedScene::set_reference(DepthReference r)
+{
+	reference = r;
+}
+
+void ZSortedScene::render(Renderer &renderer, const Tag &tag) const
+{
+	const Camera *camera = renderer.get_camera();
+	if(!camera)
+		return SimpleScene::render(renderer, tag);
+
+	const Matrix &view_matrix = camera->get_matrix();
+
+	std::vector<DepthRenderable> sorted_renderables;
+	sorted_renderables.reserve(renderables.size());
+
+	float radius_factor = 1.0f-reference;
+	float sign = order*2.0f-1.0f;
+
+	setup_cullers(renderer);
+	for(RenderableSet::const_iterator i=renderables.begin(); i!=renderables.end(); ++i)
+		if(!cull(renderer, **i))
+		{
+			float z = 0;
+			if(const Matrix *model_matrix = (*i)->get_matrix())
+			{
+				if(const Geometry::BoundingSphere<float, 3> *bsphere = (*i)->get_bounding_sphere())
+					z = (view_matrix**model_matrix*Vector4(bsphere->get_center(), 1.0f)).z+bsphere->get_radius()*radius_factor;
+				else
+					z = (view_matrix**model_matrix*Vector4(0.0f, 0.0f, 0.0f, 1.0f)).z;
+			}
+			sorted_renderables.push_back(DepthRenderable(z*sign, *i));
+		}
+
+	sort(sorted_renderables.begin(), sorted_renderables.end());
+
+	for(vector<DepthRenderable>::const_iterator i=sorted_renderables.begin(); i!=sorted_renderables.end(); ++i)
+		i->renderable->render(renderer, tag);
+}
+
+
+ZSortedScene::DepthRenderable::DepthRenderable(float d, const Renderable *r):
+	depth(d),
+	renderable(r)
+{ }
+
+} // namespace GL
+} // namespace Msp
diff --git a/source/zsortedscene.h b/source/zsortedscene.h
new file mode 100644
index 00000000..f9f6f7ee
--- /dev/null
+++ b/source/zsortedscene.h
@@ -0,0 +1,57 @@
+#ifndef MSP_GL_ZSORTEDSCENE_H_
+#define MSP_GL_ZSORTEDSCENE_H_
+
+#include "simplescene.h"
+
+namespace Msp {
+namespace GL {
+
+enum SortOrder
+{
+	FRONT_TO_BACK,
+	BACK_TO_FRONT
+};
+
+enum DepthReference
+{
+	CLOSEST,
+	CENTER,
+	FURTHEST
+};
+
+/**
+Sorts renderables by their distance from the camera before rendering.  Requires
+renderables to have a matrix.
+*/
+class ZSortedScene: public SimpleScene
+{
+private:
+	struct DepthRenderable
+	{
+		float depth;
+		const Renderable *renderable;
+
+		DepthRenderable(float, const Renderable *);
+
+		bool operator<(const DepthRenderable &o) const { return depth<o.depth; }
+	};
+
+	SortOrder order;
+	DepthReference reference;
+
+public:
+	ZSortedScene();
+
+	/// Sets the sort order.  Default is back to front.
+	void set_order(SortOrder);
+
+	/// Sets the reference point for sorting.  Default is furthest from camera.
+	void set_reference(DepthReference);
+
+	virtual void render(Renderer &, const Tag &) const;
+};
+
+} // namespace GL
+} // namespace Msp
+
+#endif