How can I orient points (and thus the geo that is copied onto it) so that they're always pointing ‘up’, while still facing in their direction of movement? Like people walking up a hill - they're facing in the direciton they're walking, but they're always vertical, not perpendicular to the hill's surface.
I've been flailing about trying to rotate normals for a few hours now - I'm sure its some basic maths which is lost on me.
Attached is a scene illustrating my problem (some may recognise it
) - help as always is greatly appreciated!

