A gaze goal expressed as a matrix whose first row points opposite the surface normal.
Mirrors tbp/monty/geometry.py::GazeDirection. Like the Python type it cannot
be rotated: Monty.Cmp.Message.transform_morphological_features/3 refuses to
transform it.
Summary
Functions
The gaze direction: the negated surface normal.
Types
@type t() :: %Monty.Geometry.GazeDirection{value: [[float() | nil]]}