no, sorry my engine is not open source. I used the project mainly for experiments, it was never intended to be a open or commercial project and I simple have not the time to maintain an other open source project.
>I myself will go for quadtree continious LOD, where I
>will make a cube of 6 2D planes and map it to a sphere.
similar to my approach
my terrain engine is a mix between several techniques. I use quadtrees for space subdivision and ROAM for continuous triangulation. The default ROAM implementation does not scale very well (esp. if you are moving fast), thats the reason why i decided to use a more memory intensive structure to traverse the mesh what simplifies normal calculation as an nice side effect. (what you really want is to access all triangles around a vertex or iterate through all triangles in a quad, right? ;-) ).
The first version was a infinite (procedural) terrain, later I added a box2sphere mapping mode which uses 3d perlin noise for terrain and texture generation.
respect! Now I have to improve my texture mapping :/