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Merged
chenkasirer merged 13 commits into from
Aug 14, 2026
Merged

Vector angles #1529

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76aebb7
apply diff from https://github.com/compas-dev/compas/pull/1462
chenkasirer Aug 12, 2026
d3d7976
added unittest for parallel projected vector angle check
chenkasirer Aug 12, 2026
68a1b09
added info to docstring
chenkasirer Aug 12, 2026
bb72498
angle_vectors raises error when one of the input vectors has length zero
chenkasirer Aug 12, 2026
9509050
removed dead code
chenkasirer Aug 12, 2026
50b0a83
removed dead code
chenkasirer Aug 12, 2026
0b2230d
updated changelog
chenkasirer Aug 12, 2026
e877dc6
better error reporting
chenkasirer Aug 12, 2026
ae069fd
tests and documentation for angles_tests as well
chenkasirer Aug 12, 2026
5073362
use tolerance passed to angle_vectorss_projected
chenkasirer Aug 12, 2026
ffeca03
Merge branch 'main' into vector_angles
chenkasirer Aug 12, 2026
6f47ee0
Merge branch 'main' into vector_angles
chenkasirer Aug 13, 2026
b4fdcae
tiny vectors but within tolerance above zero are individually allowed
chenkasirer Aug 13, 2026
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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
* Fixed `NotImplementedErorr` when calling `BrepLoop.vertices`.
* Fixed `python -m compas` to detect extensions based on `importlib` rather than `pkg_resources`.
* `compas_rhino.uninstall` will try to remove compas packages from all possible install locations.
* Changed `angle_vectors_projected` to raise `ValueError` when an input vector is parallel to projection normal.
* Changed `angle_vectors` to raise `ValueError` when one of the input vectors is a zero-length vector instead of returning 0.

### Removed

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47 changes: 23 additions & 24 deletions src/compas/geometry/_core/angles.py
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Expand Up @@ -32,6 +32,11 @@ def angle_vectors(u, v, deg=False, tol=None):
The tolerance for comparing values to zero.
Default is :attr:`TOL.absolute`.

Raises
------
ValueError
If one of the input vectors is a zero-length vector.

Returns
-------
float
Expand All @@ -44,32 +49,16 @@ def angle_vectors(u, v, deg=False, tol=None):
1.57079

"""
L = length_vector(u) * length_vector(v)
if TOL.is_zero(L, tol):
return 0
a = dot_vectors(u, v) / L
len_u = length_vector(u)
len_v = length_vector(v)

if TOL.is_zero(len_u, tol) or TOL.is_zero(len_v, tol):
raise ValueError("Cannot compute the angle between one or more zero-length vectors.")

@tomvanmele tomvanmele Aug 12, 2026

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perhaps the length check should be done on the individual vectors. otherwise two small vectors will also trigger the error, even when both vectors individually would qualify for a valid angle calculation

@tomvanmele tomvanmele Aug 12, 2026

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something like

a = length_vector(u)
b = length_vector(v)

if TOL.is_zero(a, tol) or TOL.is_zero(b, tol):
    raise ValueError(...)

cosine = dot_vectors(u, v) / (a * b)

@tomvanmele tomvanmele Aug 12, 2026

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btw, this is more or less what you do in the projected version


a = dot_vectors(u, v) / (len_u * len_v)
a = max(min(a, 1), -1)
angle = acos(a)

# a = length_vector(u)
# b = length_vector(v)
# if a < tol or b < tol:
# return 0
# c = length_vector(subtract_vectors(u, v))
# if c < tol:
# return 0
# if b >= c and c >= 0:
# mu = c - (a - b)
# elif c > b and b >= 0:
# mu = b - (a - c)
# else:
# raise Exception("Invalid input vectors.")
# angle = 2 * atan(sqrt(((a - b) + c) * mu / ((a + (b + c)) * ((a - c) + b))))

# a = normalize_vector(u)
# b = normalize_vector(v)
# angle = 2 * atan2(length_vector(subtract_vectors(a, b)), length_vector(add_vectors(a, b)))

if deg:
return degrees(angle)
return angle
Expand Down Expand Up @@ -140,6 +129,11 @@ def angle_vectors_projected(u, v, normal, deg=False, tol=None):
The tolerance for comparing values to zero.
Default is :attr:`TOL.absolute`.

Raises
------
ValueError
If one of the input vectors is parallel to the normal vector.

Returns
-------
float
Expand All @@ -155,7 +149,7 @@ def angle_vectors_projected(u, v, normal, deg=False, tol=None):
u_cross = cross_vectors(u, normal)
v_cross = cross_vectors(v, normal)

if TOL.is_allclose(u_cross, [0.0, 0.0, 0.0]) or TOL.is_allclose(v_cross, [0.0, 0.0, 0.0]):
if TOL.is_zero(length_vector(u_cross), tol) or TOL.is_zero(length_vector(v_cross), tol):
raise ValueError("Cannot compute angle between vectors projected onto a plane defined by the normal vector. One of the vectors is parallel to the normal vector.")

return angle_vectors_signed(u_cross, v_cross, normal, deg, tol)
Expand Down Expand Up @@ -283,6 +277,11 @@ def angles_vectors(u, v, deg=False):
deg : bool, optional
If True, returns the angle in degrees.

Raises
------
ValueError
If one of the input vectors is a zero-length vector.

Returns
-------
float
Expand Down
60 changes: 38 additions & 22 deletions tests/compas/geometry/test_core.py
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Expand Up @@ -61,17 +61,28 @@ def test_angle_vectors(u, v, angle):
assert TOL.is_close(angle_vectors(u, v), angle)


# @pytest.mark.parametrize(
# ("u", "v"),
# [
# ([0.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
# ([0.0, 0.0, 0.0], [1.0, 0.0, 0.0]),
# ([1.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
# ],
# )
# def test_angle_vectors_fails_when_input_is_zero(u, v):
# with pytest.raises(ZeroDivisionError):
# angle_vectors(u, v)
@pytest.mark.parametrize(
("u", "v"),
[
([1.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
([0.0, 0.0, 0.0], [1.0, 0.0, 0.0]),
([0.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
],
)
def test_angle_vectors_fails_when_input_is_zero(u, v):
with pytest.raises(ValueError):
angle_vectors(u, v)


def test_angle_vectors_fails_when_input_is_zero_within_tolerance():
# length_vector(u) == 1e-4, which is zero within tol=1e-3
with pytest.raises(ValueError):
angle_vectors([1e-4, 0.0, 0.0], [0.0, 1e-2, 0.0], tol=1e-3)


def test_angle_vectors_when_input_is_not_zero_within_tolerance():
# length_vector(u) * length_vector(v) == 1e-4, which is not zero within tol=1e-6
assert TOL.is_close(angle_vectors([1e-2, 0.0, 0.0], [0.0, 1e-2, 0.0], tol=1e-6), pi / 2)


@pytest.mark.parametrize(
Expand All @@ -93,17 +104,17 @@ def test_angles_vectors(u, v, angles):
assert TOL.is_allclose(angles_vectors(u, v), (a, b))


# @pytest.mark.parametrize(
# ("u", "v"),
# [
# ([0.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
# ([0.0, 0.0, 0.0], [1.0, 0.0, 0.0]),
# ([1.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
# ],
# )
# def test_angles_vectors_fails_when_input_is_zero(u, v):
# with pytest.raises(ZeroDivisionError):
# angles_vectors(u, v)
@pytest.mark.parametrize(
("u", "v"),
[
([1.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
([0.0, 0.0, 0.0], [1.0, 0.0, 0.0]),
([0.0, 0.0, 0.0], [0.0, 0.0, 0.0]),
],
)
def test_angles_vectors_fails_when_input_is_zero(u, v):
with pytest.raises(ValueError):
angles_vectors(u, v)


@pytest.mark.parametrize(
Expand Down Expand Up @@ -149,6 +160,11 @@ def test_angle_vectors_projected(u, v, normal, result):
assert TOL.is_close(angle_vectors_projected(u, v, normal), result)


def test_angle_vectors_projected_fails_when_input_is_parallel_to_normal():
with pytest.raises(ValueError):
angle_vectors_projected([1, 0, 0], [0, 1, 0], [1, 0, 0])


# ==============================================================================
# average
# ==============================================================================
Expand Down
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