-void Texture3D::get_level_size(unsigned level, unsigned &w, unsigned &h, unsigned &d)
+unsigned Texture3D::get_n_levels() const
+{
+ unsigned s = max(width, height);
+ if(target!=GL_TEXTURE_2D_ARRAY)
+ s = max(s, depth);
+ unsigned n = 0;
+ for(; s; s>>=1, ++n) ;
+ return n;
+}
+
+void Texture3D::get_level_size(unsigned level, unsigned &w, unsigned &h, unsigned &d) const