def normal(self, surface_point: tuple) -> tuple:
on_surf, surf_indexes = on_aabb_surface(self._size, surface_point, atol=2*EPS_ZERO)
if not on_surf:
raise GeometryError(
"Point is not on surface.",
{"point": surface_point, "geometry": self}
)
if len(surf_indexes) != 1:
raise GeometryError(
"Point is on multiple surfaces.",
{"point": surface_point, "geometry": self}
)
idx = surf_indexes[0]
# normal vector in the local frame
return NORMALS[idx]
def normal(self, surface_point: tuple) -> tuple:
""" Returns the unit surface normal at the surface_point.
"""
mesh = self.trimesh
(closest_points, distances,
triangle_id) = mesh.nearest.on_surface(np.array([surface_point]))
if closest_points.shape != (1, 3):
raise GeometryError(
'Mesh must have a single closest point to calculate normal.')
if not np.any(np.absolute(distances) < EPS_ZERO):
raise GeometryError(
'Point is not on surface.', {
"point": surface_point,
"geometry": self,
"distances": distances,
"threshold": EPS_ZERO
})
normal = tuple(mesh.face_normals[triangle_id[0]])
return normal
def is_entering(self, surface_point, direction) -> bool:
""" Returns True if the ray at surface point with direction is heading
into the shape. This is tested by checking for a negative dot product between
the vectors.
"""
if not self.is_on_surface(surface_point):
raise GeometryError("Not a surface point.")
normal = self.normal(surface_point)
if np.dot(normal, direction) < 0.0:
return True
return False
def normal(self, surface_point):
""" Normal faces outwards by convention.
"""
z = surface_point[2]
if np.isclose(z, -0.5 * self.length):
return (0.0, 0.0, -1.0)
elif np.isclose(z, 0.5 * self.length):
return (0.0, 0.0, 1.0)
elif np.isclose(self.radius, np.sqrt(np.sum(np.array(surface_point[:2]) ** 2))):
v = np.array(surface_point) - np.array([0.0, 0.0, surface_point[2]])
n = tuple(norm(v).tolist())
return n
else:
raise GeometryError("Not a surface point.")