TextureTreeNodeCore texcore = (TextureTreeNodeCore) getCore(0);
Point3D center = new Point3D();
for(int i=0; i<4; i++) {
center.add(texcore.getVertex(i));
}
center = center.divide(4);
double radius=0, newradius;
for(int i=0; i<4; i++) {
newradius = texcore.getVertex(i).sub(center).length();
if (newradius>radius) radius = newradius;