Blender Git Loki

Fix T38409: Snapping Bug

Issue partially caused by own errors (glicth in new BKE_boundbox_ray_hit_check() code causing segfault in volume snapping,
and we have to treat ortho and persp differently in case of face snapping, because in persp our ray_start might very well
already be *inside* the boundbox of the checked object), and partly due to the fact that ED_view3d_win_to_vector()
was returning wrong vector (negated one) for ortho views (see previous commit).