From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 11 Sep 2013 07:53:41 +0000 (+0300)
Subject: Add an interface for obtaining bounding spheres from renderables
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=46921b54c8252bb535a3b2cb7be97eb38e66eaed

Add an interface for obtaining bounding spheres from renderables

This can be used for various forms of culling.
---

diff --git a/source/object.cpp b/source/object.cpp
index ae38af6b..d35517bf 100644
--- a/source/object.cpp
+++ b/source/object.cpp
@@ -41,6 +41,32 @@ void Object::set_mesh(unsigned i, const Mesh *m)
 	meshes[i].keep();
 }
 
+void Object::update_bounding_sphere()
+{
+	vector<Vector3> points;
+	for(vector<RefPtr<const Mesh> >::const_iterator i=meshes.begin(); i!=meshes.end(); ++i)
+	{
+		const VertexArray &vertices = (*i)->get_vertices();
+		int offset = vertices.get_format().offset(VERTEX3);
+		if(offset<0)
+		{
+			// TODO Handle two-dimensional meshes
+			bounding_sphere = Geometry::BoundingSphere<float, 3>();
+			return;
+		}
+
+		unsigned n_vertices = vertices.size();
+		points.reserve(points.size()+n_vertices);
+		for(unsigned j=0; j<n_vertices; ++j)
+		{
+			const float *v = vertices[j];
+			points.push_back(Vector3(v[offset], v[offset+1], v[offset+2]));
+		}
+	}
+
+	bounding_sphere = Geometry::BoundingSphere<float, 3>::from_point_cloud(points.begin(), points.end());
+}
+
 const Mesh *Object::get_mesh(unsigned i) const
 {
 	if(i>=meshes.size())
@@ -136,6 +162,11 @@ void Object::Loader::init()
 	add("lod_mesh", &Loader::mesh_lod);
 }
 
+void Object::Loader::finish()
+{
+	obj.update_bounding_sphere();
+}
+
 void Object::Loader::mesh_inline()
 {
 	RefPtr<Mesh> msh = new Mesh;
diff --git a/source/object.h b/source/object.h
index 7820d29c..82e12f14 100644
--- a/source/object.h
+++ b/source/object.h
@@ -33,8 +33,8 @@ public:
 		Loader(Object &, Collection &);
 	private:
 		void init();
+		virtual void finish();
 
-	private:
 		void mesh_inline();
 		void mesh_inline_lod(unsigned);
 		void mesh(const std::string &);
@@ -46,6 +46,7 @@ public:
 private:
 	std::vector<RefPtr<const Mesh> > meshes;
 	RefPtr<const Technique> technique;
+	Geometry::BoundingSphere<float, 3> bounding_sphere;
 
 public:
 	Object();
@@ -54,10 +55,15 @@ public:
 
 	void set_mesh(const Mesh *m) { set_mesh(0, m); }
 	void set_mesh(unsigned, const Mesh *);
+private:
+	void update_bounding_sphere();
+public:
 	const Mesh *get_mesh(unsigned = 0) const;
 	void set_technique(const Technique *);
 	const Technique *get_technique() const { return technique.get(); }
 
+	virtual const Geometry::BoundingSphere<float, 3> *get_bounding_sphere() const { return &bounding_sphere; }
+
 	virtual void render(const Tag &tag = Tag()) const;
 
 	virtual void render(Renderer &, const Tag & = Tag()) const;
diff --git a/source/objectinstance.cpp b/source/objectinstance.cpp
index e3bb8f80..b3fc133d 100644
--- a/source/objectinstance.cpp
+++ b/source/objectinstance.cpp
@@ -1,4 +1,3 @@
-#include "object.h"
 #include "objectinstance.h"
 #include "renderer.h"
 
diff --git a/source/objectinstance.h b/source/objectinstance.h
index 6094517b..6a874976 100644
--- a/source/objectinstance.h
+++ b/source/objectinstance.h
@@ -2,12 +2,12 @@
 #define MSP_GL_OBJETCINSTANCE_H_
 
 #include <string>
+#include "object.h"
 #include "renderable.h"
 
 namespace Msp {
 namespace GL {
 
-class Object;
 class ProgramData;
 
 /**
@@ -29,6 +29,8 @@ public:
 	const Object &get_object() const { return object; }
 	virtual long get_instance_key() const { return reinterpret_cast<long>(&object); }
 
+	virtual const Geometry::BoundingSphere<float, 3> *get_bounding_sphere() const { return object.get_bounding_sphere(); }
+
 	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 b53fa9ac..eae75cce 100644
--- a/source/renderable.h
+++ b/source/renderable.h
@@ -2,6 +2,7 @@
 #define MSP_GL_RENDERABLE_H_
 
 #include <string>
+#include <msp/geometry/boundingsphere.h>
 #include "tag.h"
 
 namespace Msp {
@@ -38,6 +39,11 @@ public:
 	matrix exists. */
 	virtual const Matrix *get_matrix() const { return 0; }
 
+	/** Returns a bounding sphere that completely encloses the Renderable.  The
+	bounding sphere is expressed in the renderable's coordinates.  Null is
+	returned if the bounding sphere cannot be determined. */
+	virtual const Geometry::BoundingSphere<float, 3> *get_bounding_sphere() const { return 0; }
+
 	/** Called when starting to render a new frame. */
 	virtual void setup_frame() const { }