Some questions about the technologies used in Overgrowth

[Froyok]

Hi people.
I have some questions about the technologies used in Overgrowth.
I read quite the pages of the blog, but a question always tap.
And if it is not under secret of state , I would have liked knowing two things :

1 - Which are the software of used depiction : Opengl or directX ? I think that it is a question of opengl, seen the portability of the project under Linux.

2 - How are returned grounds in the game ? Is it about grounds pre-depiction? Either it's of the deformations in-game (as the displacement of Half-life 2, either the mapping under crysis).
And, what is the name of this technologie ?

For 2, I ask for that because I also develop a game, with big environment outsides. And for the moment I do not know too much in which direction to look.

_______________
I finish on a blow of publicity, if one in it straight ahead: http://www.moddb.com/games/exil
This is my project.

[Jeff]

for #1, we use OpenGL

for #2, I don't really understand the question, but let me know if these links don't answer it:
http://blog.wolfire.com/2008/10/terrain-part-1/
http://blog.wolfire.com/2008/12/off-the-grid-terrain/

[Froyok]

Thanks for your answer !
I read this blog pages right now !