It's because the vertex normal is not parallel to the eyes,
maybe try to draw the line from the eye's coordinate.

Also, with : obstacle_distance = c_trace (actorEntity, vector(temprange,0,0), IGNORE_ME + USE_BOX);

it always trace to world x-axis, that means when your character panned
to face other direction, the ray will not follow, you have to vec_rotate
the starting trace position.