diff --git a/TODO b/TODO
index a216054..225a256 100644
--- a/TODO
+++ b/TODO
@@ -2,14 +2,9 @@ BUGS:
 	- fseek with negative offset on ps2 over ps2link messes up the current position
 
 Clump & related:
-	- make pointer arrays into lists
 	- !!! work on ref counts, destruction, copying etc.
 	- define and use types:
-		sphere
-		matrix
 		color
-		realcolor
-		vector3
 		triangle
 		texcoord
 	- implement plugins:
diff --git a/src/clump.cpp b/src/clump.cpp
index 4d07c82..05f5b2c 100644
--- a/src/clump.cpp
+++ b/src/clump.cpp
@@ -568,14 +568,14 @@ Atomic::create(void)
 	assert(atomic != NULL);
 	atomic->object.init(Atomic::ID, 0);
 	atomic->geometry = NULL;
+	atomic->worldBoundingSphere.center.set(0.0f, 0.0f, 0.0f);
+	atomic->worldBoundingSphere.radius = 0.0f;
+	atomic->setFrame(NULL);
 	atomic->clump = NULL;
 	atomic->pipeline = NULL;
 	atomic->renderCB = Atomic::defaultRenderCB;
 	atomic->object.flags = Atomic::COLLISIONTEST | Atomic::RENDER;
 	atomic->constructPlugins();
-
-	// private flags:
-	// rpATOMICPRIVATEWORLDBOUNDDIRTY = 0x01
 	return atomic;
 }
 
@@ -606,6 +606,22 @@ Atomic::destroy(void)
 	free(this);
 }
 
+Sphere*
+Atomic::getWorldBoundingSphere(void)
+{
+	Sphere *s = &this->worldBoundingSphere;
+	if(!this->getFrame()->dirty() &&
+	   (this->object.privateFlags & WORLDBOUNDDIRTY) == 0)
+		return s;
+	Matrix *ltm = this->getFrame()->getLTM();
+	// TODO: support scaling
+	s->center = ltm->transPoint(s->center);
+	// TODO: if we ever support morphing, fix this:
+	s->radius = this->geometry->morphTargets[0].boundingSphere.radius;
+	this->object.privateFlags &= ~WORLDBOUNDDIRTY;
+	return s;
+}
+
 static uint32 atomicRights[2];
 
 Atomic*
diff --git a/src/rwobjects.h b/src/rwobjects.h
index 59296e8..362e25f 100644
--- a/src/rwobjects.h
+++ b/src/rwobjects.h
@@ -119,6 +119,8 @@ struct Frame : PluginBase<Frame>
 	Frame *getParent(void){
 		return (Frame*)this->object.parent; }
 	int32 count(void);
+	bool32 dirty(void) {
+		return !!(this->root->object.privateFlags & HIERARCHYSYNC); }
 	Matrix *getLTM(void);
 	void updateObjects(void);
 
@@ -558,11 +560,14 @@ struct Atomic : PluginBase<Atomic>
 	enum { ID = 1 };
 	enum {
 		COLLISIONTEST = 0x01,	// unused here
-		RENDER = 0x04
+		RENDER = 0x04,
+	// private
+		WORLDBOUNDDIRTY = 0x01
 	};
 
 	ObjectWithFrame object;
 	Geometry *geometry;
+	Sphere worldBoundingSphere;
 	Clump *clump;
 	LLLink inClump;
 	ObjPipeline *pipeline;
@@ -571,17 +576,21 @@ struct Atomic : PluginBase<Atomic>
 	static Atomic *create(void);
 	Atomic *clone(void);
 	void destroy(void);
-	void setFrame(Frame *f) { this->object.setFrame(f); }
+	void setFrame(Frame *f) {
+		this->object.setFrame(f);
+		this->object.privateFlags |= WORLDBOUNDDIRTY;
+	}
 	Frame *getFrame(void) { return (Frame*)this->object.parent; }
 	static Atomic *fromClump(LLLink *lnk){
 		return LLLinkGetData(lnk, Atomic, inClump); }
+	ObjPipeline *getPipeline(void);
+	Sphere *getWorldBoundingSphere(void);
 	static Atomic *streamReadClump(Stream *stream,
-	Frame **frameList, Geometry **geometryList);
+		Frame **frameList, Geometry **geometryList);
+	void render(void) { this->renderCB(this); }
 	bool streamWriteClump(Stream *stream,
 	Frame **frameList, int32 numframes);
 	uint32 streamGetSize(void);
-	ObjPipeline *getPipeline(void);
-	void render(void) { this->renderCB(this); }
 
 	static void defaultRenderCB(Atomic *atomic);
 };