Halo check this :
http://www.blitzbasic.com/Community/posts.php?topic=26738#279339
As you read this a massive land 524288x524288 units terrain.
No linepick, just find what quad of the terran mesh is inside your position (if your mesh terran is formated in certain manner) and perform a pseudo linepick function just in the two triangles of this quad, returning the intersection point + angle of greater slope + sliding vector.
Blitz collision detection is inacurate beyond 8000 units.
It's why i use now the Nuclear Glory detection collision.
http://www.blitzbasic.com/Community/posts.php?topic=26738#279339
As you read this a massive land 524288x524288 units terrain.
No linepick, just find what quad of the terran mesh is inside your position (if your mesh terran is formated in certain manner) and perform a pseudo linepick function just in the two triangles of this quad, returning the intersection point + angle of greater slope + sliding vector.
Blitz collision detection is inacurate beyond 8000 units.
It's why i use now the Nuclear Glory detection collision.