Some tuning.

tests/bezier_tests.py

@@ -87,11 +87,32 @@ def test_blend_second(self):
         a0r = curve.second_derivative(0)
         a1r = curve.second_derivative(1)
 
-        self.assert_numpy_arrays_equal(v0r, v0)
-        self.assert_numpy_arrays_equal(v1r, v1)
-        self.assert_numpy_arrays_equal(a0r, a0)
+        self.assert_numpy_arrays_equal(v0r, v0, precision=6)
+        self.assert_numpy_arrays_equal(v1r, v1, precision=6)
+        self.assert_numpy_arrays_equal(a0r, a0, precision=6)
         self.assert_numpy_arrays_equal(a1r, a1, precision=8)
 
+    def test_blend_second_2(self):
+        p0 = np.array([-0.12, -1.75, 0])
+        v0 = np.array([0.69, -0.05, 0])
+        a0 = np.array([-2.75, 42.64, 0])
+        p1 = np.array([0.57, -1.5, 0])
+        v1 = np.array([-0.31, 0.07, 0])
+        a1 = np.array([0.15, 1.05, 0])
+
+        curve = SvBezierCurve.blend_second_derivatives(p0, v0, a0, p1, v1, a1)
+
+        v0r = curve.tangent(0)
+        v1r = curve.tangent(1)
+
+        a0r = curve.second_derivative(0)
+        a1r = curve.second_derivative(1)
+
+        self.assert_numpy_arrays_equal(v0r, v0, precision=6)
+        self.assert_numpy_arrays_equal(v1r, v1, precision=6)
+        self.assert_numpy_arrays_equal(a0r, a0, precision=6)
+        self.assert_numpy_arrays_equal(a1r, a1, precision=6)
+
     def test_blend_third(self):
         p0 = np.array([0, 0, 0])
         p1 = np.array([3, 0, 0])

utils/curve/fillet.py

@@ -29,13 +29,14 @@
 SMOOTH_NORMAL = '2'
 SMOOTH_CURVATURE = '3'
 
-def calc_single_fillet(smooth, curve1, curve2, bulge_factor = 0.5, biarc_parameter = 1.0, planar_tolerance = 1e-6):
+def calc_single_fillet(smooth, curve1, curve2, t_span, bulge_factor = 0.5, biarc_parameter = 1.0, planar_tolerance = 1e-6):
+    #t_span = 1.0
     u1_max = curve1.get_u_bounds()[1]
     u2_min = curve2.get_u_bounds()[0]
     curve1_end = curve1.evaluate(u1_max)
     curve2_begin = curve2.evaluate(u2_min)
-    tangent1_end = curve1.get_end_tangent()
-    tangent2_begin = curve2.get_start_tangent()
+    tangent1_end = t_span * curve1.get_end_tangent()
+    tangent2_begin = t_span * curve2.get_start_tangent()
 
     if smooth == SMOOTH_POSITION:
         return SvLine.from_two_points(curve1_end, curve2_begin)
@@ -57,16 +58,19 @@ def calc_single_fillet(smooth, curve1, curve2, bulge_factor = 0.5, biarc_paramet
                 biarc_parameter,
                 planar_tolerance = planar_tolerance)
     elif smooth == SMOOTH_NORMAL:
-        second_1_end = curve1.second_derivative(u1_max)
-        second_2_begin = curve2.second_derivative(u2_min)
+        second_1_end = t_span**2 * curve1.second_derivative(u1_max)
+        second_2_begin = t_span**2 * curve2.second_derivative(u2_min)
+        #print(f"T: {t_span**2}")
+        #print(f"E: {curve1_end}, {tangent1_end}, {second_1_end}")
+        #print(f"B: {curve2_begin}, {tangent2_begin}, {second_2_begin}")
         return SvBezierCurve.blend_second_derivatives(
                         curve1_end, tangent1_end, second_1_end,
                         curve2_begin, tangent2_begin, second_2_begin)
     elif smooth == SMOOTH_CURVATURE:
-        second_1_end = curve1.second_derivative(u1_max)
-        second_2_begin = curve2.second_derivative(u2_min)
-        third_1_end = curve1.third_derivative_array(np.array([u1_max]))[0]
-        third_2_begin = curve2.third_derivative_array(np.array([u2_min]))[0]
+        second_1_end = t_span**2 * curve1.second_derivative(u1_max)
+        second_2_begin = t_span**2 * curve2.second_derivative(u2_min)
+        third_1_end = t_span**3 * curve1.third_derivative_array(np.array([u1_max]))[0]
+        third_2_begin = t_span**3 * curve2.third_derivative_array(np.array([u2_min]))[0]
 
         return SvBezierCurve.blend_third_derivatives(
                         curve1_end, tangent1_end, second_1_end, third_1_end,
@@ -78,17 +82,17 @@ def cut_ends(curve, cut_offset, cut_start=True, cut_end=True):
     u_min, u_max = curve.get_u_bounds()
     p1, p2 = curve.get_end_points()
     l = np.linalg.norm(p1 - p2)
-    dt = u_max - u_min
+    dt = cut_offset * (u_max - u_min)
     if cut_start:
-        u1 = u_min + cut_offset*dt
+        u1 = u_min + dt
     else:
         u1 = u_min
     if cut_end:
-        u2 = u_max - cut_offset*dt
+        u2 = u_max - dt
     else:
         u2 = u_max
     #print(f"cut: {u_min} - {u_max} * cut_offset => {u1} - {u2}")
-    return curve.cut_segment(u1, u2)
+    return dt, curve.cut_segment(u1, u2)
 
 def limit_filet_radiuses(vertices, radiuses, cyclic=False):
     factor = 0.999
@@ -145,11 +149,14 @@ def fillet_nurbs_curve(curve, smooth, cut_offset,
     cyclic = curve.is_closed()
     segments = curve.split_at_fracture_points(tangent_tolerance = tangent_tolerance)
     n = len(segments)
-    segments = [cut_ends(s, cut_offset, cut_start = (i > 0 or cyclic), cut_end = (i < n-1 or cyclic)) for i, s in enumerate(segments)]
-    fillets = [calc_single_fillet(smooth, s1, s2, bulge_factor, biarc_parameter, planar_tolerance) for s1, s2 in zip(segments, segments[1:])]
+    cuts = [cut_ends(s, cut_offset, cut_start = (i > 0 or cyclic), cut_end = (i < n-1 or cyclic)) for i, s in enumerate(segments)]
+    fillets = [calc_single_fillet(smooth, s1, s2, dt1+dt2, bulge_factor, biarc_parameter, planar_tolerance) for (dt1,s1), (dt2,s2) in zip(cuts, cuts[1:])]
     if cyclic:
-        fillet = calc_single_fillet(smooth, segments[-1], segments[0], bulge_factor, biarc_parameter, planar_tolerance)
+        dt1, s1 = cuts[-1]
+        dt2, s2 = cuts[0]
+        fillet = calc_single_fillet(smooth, s1, s2, dt1+dt2, bulge_factor, biarc_parameter, planar_tolerance)
         fillets.append(fillet)
+    segments = [cut[1] for cut in cuts]
     new_segments = [[segment, fillet] for segment, fillet in zip(segments, fillets)]
     if not cyclic:
         new_segments.append([segments[-1]])