lazy bounding radius computing for shape_node (avoids O(n^2) deserialization)

scene.cpp

@@ -259,7 +259,7 @@ basic_cell::insert( shape_node Shape ) {
     // re-calculate cell radius, in case shape geometry extends outside the cell's boundaries
     m_area.radius = std::max<float>(
         m_area.radius,
-        glm::length( m_area.center - Shape.data().area.center ) + Shape.data().area.radius );
+	    glm::length( m_area.center - Shape.data().area.center ) + Shape.radius() );
 
     auto const &shapedata { Shape.data() };
     auto &shapes = (
@@ -1230,7 +1230,7 @@ basic_region::insert( shape_node Shape, scratch_data &Scratchpad, bool const Tra
     // move the data into appropriate section(s)
     for( auto &shape : shapes ) {
         // with the potential splitting done we can calculate each chunk's bounding radius
-        shape.compute_radius();
+		shape.invalidate_radius();
         if( point_inside( shape.m_data.area.center ) ) {
             // NOTE: nodes placed outside of region boundaries are discarded
             section( shape.m_data.area.center ).insert( shape );

scenenode.cpp

@@ -410,8 +410,7 @@ shape_node::merge( shape_node &Shape ) {
     m_data.vertices.insert(
         std::end( m_data.vertices ),
         std::begin( Shape.m_data.vertices ), std::end( Shape.m_data.vertices ) );
-    // NOTE: we could recalculate radius with something other than brute force, but it'll do
-    compute_radius();
+	invalidate_radius();
 
     return true;
 }
@@ -445,7 +444,16 @@ shape_node::compute_radius() {
     m_data.area.radius = static_cast<float>( std::sqrt( squaredradius ) );
 }
 
+void shape_node::invalidate_radius() {
+	m_data.area.radius = -1.0f;
+}
 
+float shape_node::radius() {
+	if (m_data.area.radius == -1.0f)
+		compute_radius();
+
+	return m_data.area.radius;
+}
 
 // sends content of the struct to provided stream
 void

scenenode.h

@@ -126,7 +126,10 @@ public:
         create_geometry( gfx::geometrybank_handle const &Bank );
     // calculates shape's bounding radius
     void
-        compute_radius();
+	    compute_radius();
+	// invalidates shape's bounding radius
+	void
+	    invalidate_radius();
     // set visibility
     void
         visible( bool State );
@@ -136,6 +139,8 @@ public:
     // data access
     shapenode_data const &
         data() const;
+	// get bounding radius
+	float radius();
 
 private:
 // members