Fixed zero length segment for vertical alignment. Refactors curve segment transition code

src/ifcopenshell-python/ifcopenshell/api/alignment/_map_alignment_vertical_segment.py

@@ -143,6 +143,9 @@ def _map_circular_arc(file: ifcopenshell.file, design_parameters: entity_instanc
     end_angle = math.atan(end_gradient)
     dx = math.cos(start_angle)
     dy = math.sin(start_angle)
+
+    # start and end angles are for the curve tangents
+    # convert them to be angles of the radii lines
     if start_angle < end_angle:
         radius = horizontal_length / (math.sin(end_angle) - math.sin(start_angle))
         x = -radius * math.sin(start_angle)
@@ -158,14 +161,12 @@ def _map_circular_arc(file: ifcopenshell.file, design_parameters: entity_instanc
 
     parent_curve = file.createIfcCircle(
         Position=file.createIfcAxis2Placement2D(
-            Location=file.createIfcCartesianPoint((0.0, 0.0)),
+            Location=file.createIfcCartesianPoint((x, y)),
             RefDirection=file.createIfcDirection((1.0, 0.0)),
         ),
         Radius=radius,
     )
 
-    segment_curve_length = radius * math.fabs(end_angle - start_angle)
-
     curve_segment = file.create_entity(
         type="IfcCurveSegment",
         Transition=transition,

src/ifcopenshell-python/ifcopenshell/api/alignment/add_zero_length_segment.py

@@ -27,6 +27,7 @@ import math
 
 from ifcopenshell.api.alignment._get_segment_start_point_label import _get_segment_start_point_label
 from ifcopenshell.api.alignment._map_alignment_horizontal_segment import _map_alignment_horizontal_segment
+from ifcopenshell.api.alignment._map_alignment_vertical_segment import _map_alignment_vertical_segment
 from ifcopenshell.api.alignment._update_curve_segment_transition_code import _update_curve_segment_transition_code
 
 
@@ -157,20 +158,35 @@ def add_zero_length_segment(file: ifcopenshell.file, layout: entity_instance, in
             )
         elif layout.is_a("IfcAlignmentVertical"):
             last_segment_dist_along = 0.0
+            last_segment_height = 0.0
             last_segment_end_gradient = 0.0
+            last_segment = None
             for rel in layout.IsNestedBy:
                 if 0 < len(rel.RelatedObjects):
                     last_segment = rel.RelatedObjects[-1]
-                    last_segment_dist_along = (
-                        last_segment.DesignParameters.StartDistAlong + last_segment.DesignParameters.HorizontalLength
-                    )
-                    last_segment_end_gradient = last_segment.DesignParameters.EndGradient
                     break
 
+            if last_segment:
+                file.begin_transaction()
+                last_segment_dist_along = (
+                    last_segment.DesignParameters.StartDistAlong + last_segment.DesignParameters.HorizontalLength
+                )
+                last_segment_end_gradient = last_segment.DesignParameters.EndGradient
+                settings = ifcopenshell.geom.settings()
+                mapped_segments = _map_alignment_vertical_segment(file, last_segment)
+                geometry_segment = mapped_segments[0] if mapped_segments[1] == None else mapped_segments[1]
+                fn = wrapper.map_shape(settings, geometry_segment.wrapped_data)
+                eval = wrapper.function_item_evaluator(settings, fn)
+                e = np.array(eval.evaluate(fn.end()))
+                unit_scale = ifcopenshell.util.unit.calculate_unit_scale(file)
+                last_segment_height = float(e[1, 3]) / unit_scale
+
+                file.discard_transaction()
+
             design_parameters = file.createIfcAlignmentVerticalSegment(
                 StartDistAlong=last_segment_dist_along,
                 HorizontalLength=0.0,
-                StartHeight=0.0,
+                StartHeight=last_segment_height,
                 StartGradient=last_segment_end_gradient,
                 EndGradient=last_segment_end_gradient,
                 PredefinedType="CONSTANTGRADIENT",

src/ifcopenshell-python/ifcopenshell/api/alignment/get_curve_segment_transition_code.py

@@ -26,47 +26,52 @@ import math
 
 
 def get_curve_segment_transition_code(
-    prev_segment: entity_instance, segment: entity_instance, tolerance: float = 5.0e-4
+    segment: entity_instance, next_segment: entity_instance, position_tolerance: float = 0.001
 ) -> str:
     """
-    Returns the  IfcCurveSegment.Transition of prev_segment based on a comparison of
-    the position, ref. direction, and curvature at the end of the prev_segment and the start of segment.
+    Returns the IfcCurveSegment.Transition of segment based on a comparison of
+    the position, ref. direction, and curvature at the end of the segment and the start of next_segment.
+
+    :param segment: segment for which the position curve is being being determined
+    :param next_segment: next segment
+    :param position_tolerance: tolerance used for evaluation positions. The default is 1mm
+    :return: the transition code
     """
     expected_type = "IfcCurveSegment"
-    if not prev_segment.is_a(expected_type):
-        raise TypeError(f"Expected to see '{expected_type}', instead received '{prev_segment.is_a()}'.")
-
     if not segment.is_a(expected_type):
         raise TypeError(f"Expected to see '{expected_type}', instead received '{segment.is_a()}'.")
 
-    if len(prev_segment.UsingCurves) != 1:
-        raise TypeError("prev_segment must belong to exactly one curve")
+    if not next_segment.is_a(expected_type):
+        raise TypeError(f"Expected to see '{expected_type}', instead received '{next_segment.is_a()}'.")
 
     if len(segment.UsingCurves) != 1:
         raise TypeError("segment must belong to exactly one curve")
 
-    if prev_segment.UsingCurves[0] != segment.UsingCurves[0]:
+    if len(next_segment.UsingCurves) != 1:
+        raise TypeError("next_segment must belong to exactly one curve")
+
+    if segment.UsingCurves[0] != next_segment.UsingCurves[0]:
         raise TypeError("Both segments must belong to the same curve")
 
     settings = ifcopenshell.geom.settings()
     settings.set("COMPUTE_CURVATURE", True)
 
-    prev_segment_fn = ifcopenshell_wrapper.map_shape(settings, prev_segment.wrapped_data)
-    prev_segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, prev_segment_fn)
-    e = prev_segment_evaluator.evaluate(prev_segment_fn.end())
+    segment_fn = ifcopenshell_wrapper.map_shape(settings, segment.wrapped_data)
+    segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, segment_fn)
+    e = segment_evaluator.evaluate(segment_fn.end())
     end = np.array(e)
 
     # must add the new segment to the container before mapping it, otherwise the segment doesn't
     # have enough context to know if it is for horizontal, vertical, cant
 
-    segment_fn = ifcopenshell_wrapper.map_shape(settings, segment.wrapped_data)
-    segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, segment_fn)
-    s = segment_evaluator.evaluate(segment_fn.start())
+    next_segment_fn = ifcopenshell_wrapper.map_shape(settings, next_segment.wrapped_data)
+    next_segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, next_segment_fn)
+    s = next_segment_evaluator.evaluate(next_segment_fn.start())
     start = np.array(s)
 
-    same_position = True if np.allclose(end[:3, 3], start[:3, 3], atol=tolerance) else False
-    same_gradient = True if np.allclose(end[:3, 0], start[:3, 0], atol=tolerance) else False
-    same_curvature = True if np.allclose(end[3:, :3], start[3:, :3], atol=tolerance) else False
+    same_position = True if np.allclose(end[:3, 3], start[:3, 3], atol=position_tolerance) else False
+    same_gradient = True if np.allclose(end[:3, 0], start[:3, 0]) else False
+    same_curvature = True if np.allclose(end[3:, :3], start[3:, :3]) else False
 
     transition_code = ""
     if same_position: