First attempt at ripping out agnostic code into ifcopenshell.api namespace. See #1399.

src/ifcopenshell-python/ifcopenshell/api/grid/create_axis_curve.py

@@ -0,0 +1,44 @@
+import ifcopenshell
+import ifcopenshell.util.unit
+import ifcopenshell.util.placement
+from mathutils import Matrix  # For now, we depend on Blender
+
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {
+            "AxisCurve": None,  # A Blender object
+            "grid_axis": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        if self.settings["grid_axis"].AxisCurve:
+            ifcopenshell.util.element.remove_deep(self.file, self.settings["grid_axis"].AxisCurve)
+
+        self.settings["unit_scale"] = ifcopenshell.util.unit.calculate_unit_scale(self.file)
+        grid = [i for i in self.file.get_inverse(self.settings["grid_axis"]) if i.is_a("IfcGrid")][0]
+        points = [
+            Matrix(ifcopenshell.util.placement.get_local_placement(grid.ObjectPlacement)).inverted()
+            @ (self.settings["AxisCurve"].matrix_world @ v.co)
+            for v in self.settings["AxisCurve"].data.vertices[0:2]
+        ]
+        self.settings["grid_axis"].AxisCurve = self.file.createIfcPolyline(
+            [
+                self.create_cartesian_point(points[0][0], points[0][1], points[0][2]),
+                self.create_cartesian_point(points[1][0], points[1][1], points[1][2]),
+            ]
+        )
+
+    def create_cartesian_point(self, x, y, z=None):
+        x = self.convert_si_to_unit(x)
+        y = self.convert_si_to_unit(y)
+        if z is None:
+            return self.file.createIfcCartesianPoint((x, y))
+        z = self.convert_si_to_unit(z)
+        return self.file.createIfcCartesianPoint((x, y, z))
+
+    def convert_si_to_unit(self, co):
+        return co / self.settings["unit_scale"]

src/ifcopenshell-python/ifcopenshell/api/grid/create_grid_axis.py

@@ -0,0 +1,21 @@
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {
+            "AxisTag": "A",
+            "SameSense": True,
+            "UVWAxes": "UAxes",  # Choose which axes
+            "Grid": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        element = self.file.create_entity("IfcGridAxis", **{
+            "AxisTag": self.settings["AxisTag"],
+            "SameSense": self.settings["SameSense"]
+        })
+        axes = list(getattr(self.settings["Grid"], self.settings["UVWAxes"]) or [])
+        axes.append(element)
+        setattr(self.settings["Grid"], self.settings["UVWAxes"], axes)
+        return element