From 9e64974cb0ed09c9ddf84b191658be2311fd4308 Mon Sep 17 00:00:00 2001
From: Korijn van Golen <korijn@gmail.com>
Date: Fri, 27 Dec 2024 09:46:32 +0100
Subject: [PATCH 1/3] add unit test to compare to old implementation

---
 tests/test_matrix.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tests/test_matrix.py b/tests/test_matrix.py
index bfcaa73..d77e7b7 100644
--- a/tests/test_matrix.py
+++ b/tests/test_matrix.py
@@ -268,6 +268,26 @@ def test_mat_compose_validation():
         la.mat_decompose(matrix, scaling_signs=signs)
 
 
+def naive_mat_compose(translation, rotation, scaling, /, *, out=None, dtype=None):
+    return la.mat_combine(
+        [
+            la.mat_from_translation(translation),
+            la.mat_from_quat(rotation),
+            la.mat_from_scale(scaling),
+        ],
+        out=out,
+        dtype=dtype,
+    )
+
+
+def test_mat_compose_naive():
+    """Compare the direct composition with the naive composition."""
+    npt.assert_almost_equal(
+        la.mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], [1, -2, 9]),
+        naive_mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], [1, -2, 9]),
+    )
+
+
 def test_mat_perspective():
     a = la.mat_perspective(-1, 1, -1, 1, 1, 100)
     npt.assert_array_almost_equal(

From 5aad0996ed3576a0f836e6fc06c50732b2c69044 Mon Sep 17 00:00:00 2001
From: Korijn van Golen <korijn@gmail.com>
Date: Fri, 27 Dec 2024 10:01:11 +0100
Subject: [PATCH 2/3] add support & test for scalar scaling argument to
 mat_compose

---
 pylinalg/matrix.py   | 39 ++++++++++++++++++++-------------------
 tests/test_matrix.py | 15 ++++++++++++++-
 2 files changed, 34 insertions(+), 20 deletions(-)

diff --git a/pylinalg/matrix.py b/pylinalg/matrix.py
index 111969c..6ca22e3 100644
--- a/pylinalg/matrix.py
+++ b/pylinalg/matrix.py
@@ -323,27 +323,28 @@ def mat_compose(translation, rotation, scaling, /, *, out=None, dtype=None):
     wy = w * y2
     wz = w * z2
 
+    scaling = np.asarray(scaling)
+    if scaling.ndim == 0:
+        scaling = np.array([scaling, scaling, scaling])
+    elif scaling.size == 1:
+        scaling = np.array([scaling[0], scaling[0], scaling[0]])
     sx, sy, sz = scaling
 
-    out.flat[0] = (1 - (yy + zz)) * sx
-    out.flat[4] = (xy + wz) * sx
-    out.flat[8] = (xz - wy) * sx
-    out.flat[12] = 0
-
-    out.flat[1] = (xy - wz) * sy
-    out.flat[5] = (1 - (xx + zz)) * sy
-    out.flat[9] = (yz + wx) * sy
-    out.flat[13] = 0
-
-    out.flat[2] = (xz + wy) * sz
-    out.flat[6] = (yz - wx) * sz
-    out.flat[10] = (1 - (xx + yy)) * sz
-    out.flat[14] = 0
-
-    out.flat[3] = translation[0]
-    out.flat[7] = translation[1]
-    out.flat[11] = translation[2]
-    out.flat[15] = 1
+    out[0, 0] = (1 - (yy + zz)) * sx
+    out[1, 0] = (xy + wz) * sx
+    out[2, 0] = (xz - wy) * sx
+    out[3, 0:3] = 0
+
+    out[0, 1] = (xy - wz) * sy
+    out[1, 1] = (1 - (xx + zz)) * sy
+    out[2, 1] = (yz + wx) * sy
+
+    out[0, 2] = (xz + wy) * sz
+    out[1, 2] = (yz - wx) * sz
+    out[2, 2] = (1 - (xx + yy)) * sz
+
+    out[0:3, 3] = translation
+    out[3, 3] = 1
 
     return out
 
diff --git a/tests/test_matrix.py b/tests/test_matrix.py
index d77e7b7..b45d590 100644
--- a/tests/test_matrix.py
+++ b/tests/test_matrix.py
@@ -282,12 +282,25 @@ def naive_mat_compose(translation, rotation, scaling, /, *, out=None, dtype=None
 
 def test_mat_compose_naive():
     """Compare the direct composition with the naive composition."""
-    npt.assert_almost_equal(
+    npt.assert_equal(
         la.mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], [1, -2, 9]),
         naive_mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], [1, -2, 9]),
     )
 
 
+def test_mat_compose_scalar_scaling():
+    """Check that a scaler scaling argument is supported in mat_compose."""
+    npt.assert_equal(
+        la.mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], [1.25, 1.25, 1.25]),
+        la.mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], 1.25),
+    )
+
+    npt.assert_equal(
+        la.mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], [1.25, 1.25, 1.25]),
+        la.mat_compose([1, 2, 3], [np.pi, np.pi / 4, 0, 1], [1.25]),
+    )
+
+
 def test_mat_perspective():
     a = la.mat_perspective(-1, 1, -1, 1, 1, 100)
     npt.assert_array_almost_equal(

From 4703ae4e2a70ea8455a93533a3d3c49f7c79e081 Mon Sep 17 00:00:00 2001
From: Korijn van Golen <korijn@gmail.com>
Date: Fri, 27 Dec 2024 10:05:06 +0100
Subject: [PATCH 3/3] simplify

---
 pylinalg/matrix.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pylinalg/matrix.py b/pylinalg/matrix.py
index 6ca22e3..70a887b 100644
--- a/pylinalg/matrix.py
+++ b/pylinalg/matrix.py
@@ -324,10 +324,8 @@ def mat_compose(translation, rotation, scaling, /, *, out=None, dtype=None):
     wz = w * z2
 
     scaling = np.asarray(scaling)
-    if scaling.ndim == 0:
-        scaling = np.array([scaling, scaling, scaling])
-    elif scaling.size == 1:
-        scaling = np.array([scaling[0], scaling[0], scaling[0]])
+    if scaling.size == 1:
+        scaling = np.broadcast_to(scaling, (3,))
     sx, sy, sz = scaling
 
     out[0, 0] = (1 - (yy + zz)) * sx