I'm getting progress with maths here ! The purple rects represent points of the walkable path. White lines are the paths, connecting those points.
The blue rect is representing the character. When moving right or left, this blue rectangle is moving along the paths.
The red line represents the camera, targeting the blue rect and perpendicular to the white lines...
So it works in 2D, now I have to adapt this into 3D. Thanks Gosu for the Gosu::angle method ! :)
EDIT :
And now in 3D ! It works pretty well, I have to calculate the position with a y variation, not yet handled.
EDIT :
And now with Y variations ! I just have to calculate soft interpolation so that angles don't change brutally in one shot each new segment.
EDIT :
I'm so happy with that ! I wasn't expeding to go that far :
http://www.youtube.com/watch?list=UU1gGK-jOC2k3RqN1QNhrXEA&feature=player_detailpage&v=YWgmlOrRsxA