Ive never used this but leave your panel showing "a.tilt"
but slot in this line before the displays...
a.tilt = cycle(a.tilt, -90, 90);
If I understand 'c_trace' and 'normal' and 'vec_to_angle' correctly,
"a.tilt" is 45 = 45 degree slope away from player
"a.tilt" is 00 = flat wall-like structure.
"a.tilt" is -45 = 45 degree slope toward player (overhanging cliff)
I may have the calculations out by 90 degrees though.