quad tree based 3D terrain rendering

So yea I kinda have been doing nothing but playing stormworks for the last 2 months so I didn't work much on this, but here's a small update to my OpenGL engine.
There's no screen-space pixel error calculation and chunk-culling based on the cameras view-frustum yet for real geomipmapping, so popping is very obvious (Although the colors set for debugging make popping even more obvious).
The low framerate is due to surface-normal-calculation in a geometry-shader for a rendering-mode not shown here.
The entire terrain is stored in one large vertex buffer, with individual chunks being created and rendered by constructing index-buffers based on the desired LOD.
Also, finding neighbors in a quad-tree fucking sucks and is kinda inefficient, so skirts might actually be a lot better at fixing LOD-chunk cracks, because there is no need to regenerate all neighboring chunks once a chunk changes its' LOD when you just yeet skirts onto every chunk. Kinda need to test this more tho.

[sbndev]

How did you subdivide terrain quads in real time? Do you update the vbo?