X.camera3D.unproject(x,y,z) is working.
Merge branch 'master' of github.com:xtk/X
X.renderer3D.pick3d(x,y) now works also on translated objects and takes the center into account.

There are two thresholds which control the picking accuracy vs. picking speed:

delta: the sample rate to find intersections in unknown depth (default: 4)
epsilon: the threshold to treat a neighboring point as a valid intersection (default: 2mm)

TODO: If an object is rotated, picking shamelessly fails.