add BSpline.degree_elevation() method

docs/source/math/core.rst

@@ -1141,6 +1141,8 @@ BSpline
 
     .. automethod:: cubic_bezier_approximation
 
+    .. automethod:: degree_elevation
+
 
 Bezier
 ------

notes/pages/CHANGELOG.md

@@ -4,7 +4,7 @@
 	- NEW: `Mesh.audit()` removes `MESH` entities without vertices or faces
 	- NEW: `Polyline.points_in_wcs()` method
 	- NEW: `EdgePath.close_gaps()` method
-	- NEW: `ezdxf.math.bspline.degree_elevation()` function
+	- NEW: `BSpline.degree_elevation()` method
 	- BUGFIX: Exported `MESH` entities  without vertices or faces create invalid DXF files
 		- {{issue 1219}}
 - ## Version 1.3.5 - 2024-12-15

src/ezdxf/math/bspline.py

@@ -1323,6 +1323,18 @@ def approximation_params(self, level: int = 3) -> Sequence[float]:
             params = list(subdivide_params(params))
         return params
 
+    def degree_elevation(self, t: int) -> BSpline:
+        """Returns a new :class:`BSpline` with a t-times elevated degree.
+
+        Degree elevation increases the degree of a curve without changing the shape of the
+        curve. This method implements the algorithm A5.9 of the "The NURBS Book" by
+        Piegl & Tiller.
+
+        .. versionadded:: 1.4
+
+        """
+        return degree_elevation(self, t)
+
 
 def subdivide_params(p: list[float]) -> Iterable[float]:
     for i in range(len(p) - 1):
@@ -1576,6 +1588,8 @@ def degree_elevation(spline: BSpline, t: int) -> BSpline:
     curve. This function implements the algorithm A5.9 of the "The NURBS Book" by
     Piegl & Tiller.
 
+    .. versionadded:: 1.4
+
     """
     # Naming and structure have been retained to facilitate comparison with the original
     # algorithm during debugging.

tests/test_06_math/test_628_bspline_tools.py

@@ -3,7 +3,7 @@
 import pytest
 
 import math
-from ezdxf.math import bspline
+from ezdxf.math import BSpline
 
 
 CONTROL_POINTS = [(0, 0), (1, -1), (2, 0), (3, 2), (4, 0), (5, -2)]
@@ -56,48 +56,48 @@
 class TestNonRationalBSpline:
     @pytest.fixture(scope="class")
     def result(self):
-        spline = bspline.BSpline(CONTROL_POINTS)
-        return bspline.degree_elevation(spline, 1)
+        spline = BSpline(CONTROL_POINTS)
+        return spline.degree_elevation(1)
 
-    def test_degree_is_elevated(self, result: bspline.BSpline):
+    def test_degree_is_elevated(self, result: BSpline):
         assert result.degree == 4
 
-    def test_clamped_start_and_end_points_are_preserved(self, result: bspline.BSpline):
+    def test_clamped_start_and_end_points_are_preserved(self, result: BSpline):
         assert result.control_points[0].isclose(CONTROL_POINTS[0])
         assert result.control_points[-1].isclose(CONTROL_POINTS[-1])
 
-    def test_expected_control_points(self, result: bspline.BSpline):
+    def test_expected_control_points(self, result: BSpline):
         assert (
             all(cp.isclose(e) for cp, e in zip(result.control_points, EXPECTED_POINTS))
             is True
         )
 
-    def test_expected_knot_values(self, result: bspline.BSpline):
+    def test_expected_knot_values(self, result: BSpline):
         assert (
             all(math.isclose(k, e) for k, e in zip(result.knots(), EXPECTED_KNOTS))
             is True
         )
 
     def test_elevation_0_times(self):
-        spline = bspline.BSpline(CONTROL_POINTS)
-        assert bspline.degree_elevation(spline, 0) is spline
-        assert bspline.degree_elevation(spline, -1) is spline
+        spline = BSpline(CONTROL_POINTS)
+        assert spline.degree_elevation(0) is spline
+        assert spline.degree_elevation(-1) is spline
 
 
 class TestRationalBSpline:
     @pytest.fixture(scope="class")
     def result(self):
-        spline = bspline.BSpline(CONTROL_POINTS, weights=WEIGHTS)
-        return bspline.degree_elevation(spline, 1)
+        spline = BSpline(CONTROL_POINTS, weights=WEIGHTS)
+        return spline.degree_elevation(1)
 
-    def test_degree_is_elevated(self, result: bspline.BSpline):
+    def test_degree_is_elevated(self, result: BSpline):
         assert result.degree == 4
 
-    def test_clamped_start_and_end_points_are_preserved(self, result: bspline.BSpline):
+    def test_clamped_start_and_end_points_are_preserved(self, result: BSpline):
         assert result.control_points[0].isclose(CONTROL_POINTS[0])
         assert result.control_points[-1].isclose(CONTROL_POINTS[-1])
 
-    def test_expected_control_points(self, result: bspline.BSpline):
+    def test_expected_control_points(self, result: BSpline):
         assert (
             all(
                 cp.isclose(e)
@@ -106,13 +106,13 @@ def test_expected_control_points(self, result: bspline.BSpline):
             is True
         )
 
-    def test_expected_knot_values(self, result: bspline.BSpline):
+    def test_expected_knot_values(self, result: BSpline):
         assert (
             all(math.isclose(k, e) for k, e in zip(result.knots(), EXPECTED_KNOTS))
             is True
         )
 
-    def test_expected_weights(self, result: bspline.BSpline):
+    def test_expected_weights(self, result: BSpline):
         assert (
             all(math.isclose(w, e) for w, e in zip(result.weights(), EXPECTED_WEIGHTS))
             is True