feat: initial otko import

tests/unit/test_section_bbox.py

@@ -0,0 +1,97 @@
+"""Tests for bbox_for_section — used to draw extruded sections in 3D."""
+
+from __future__ import annotations
+
+import math
+
+import pytest
+
+from otko.core import (
+    CircularPatch,
+    ElasticSection,
+    FiberSection,
+    Project,
+    RectangularPatch,
+    StraightLayer,
+)
+from otko.services.section_bbox import bbox_for_section
+
+
+# ── ElasticSection ────────────────────────────────────────────────
+def test_elastic_section_back_solves_rectangle() -> None:
+    """An ElasticSection is treated as a rectangle: A = b·h and
+    Iz = b·h³/12 determine (b, h) uniquely."""
+    # Known rectangle: b = 0.3, h = 0.5 → A = 0.15, Iz = 3.125e-3
+    b, h = 0.30, 0.50
+    A = b * h
+    Iz = b * h ** 3 / 12.0
+    Iy = h * b ** 3 / 12.0
+    sec = ElasticSection(
+        id=1, name="R",
+        E=200e9, A=A, Iz=Iz, Iy=Iy, G=80e9, J=1e-6,
+    )
+    dims = bbox_for_section(sec)
+    assert dims is not None
+    w_y, h_z = dims
+    assert w_y == pytest.approx(b, rel=1e-9)
+    assert h_z == pytest.approx(h, rel=1e-9)
+
+
+# ── FiberSection ──────────────────────────────────────────────────
+def test_fiber_section_bbox_from_rect_patch() -> None:
+    sec = FiberSection(
+        id=1,
+        patches=[RectangularPatch(
+            material_id=1, n_fib_y=4, n_fib_z=4,
+            y_i=-0.15, z_i=-0.25, y_j=0.15, z_j=0.25,
+        )],
+    )
+    dims = bbox_for_section(sec)
+    assert dims is not None
+    w_y, h_z = dims
+    assert w_y == pytest.approx(0.30)
+    assert h_z == pytest.approx(0.50)
+
+
+def test_fiber_section_bbox_includes_circ_patches() -> None:
+    sec = FiberSection(
+        id=1,
+        patches=[CircularPatch(
+            material_id=1, n_fib_circ=8, n_fib_rad=2,
+            y_center=0.0, z_center=0.0,
+            r_outer=0.2,
+        )],
+    )
+    dims = bbox_for_section(sec)
+    assert dims is not None
+    assert dims[0] == pytest.approx(0.40)
+    assert dims[1] == pytest.approx(0.40)
+
+
+def test_fiber_section_bbox_grows_for_layers() -> None:
+    """A bar layer that extends past the patches must widen the bbox."""
+    sec = FiberSection(
+        id=1,
+        patches=[RectangularPatch(
+            material_id=1, n_fib_y=2, n_fib_z=2,
+            y_i=-0.10, z_i=-0.10, y_j=0.10, z_j=0.10,
+        )],
+        layers=[StraightLayer(
+            material_id=2, n_bars=3, bar_area=1e-4,
+            y_start=-0.15, z_start=0.12,
+            y_end=0.15, z_end=0.12,
+        )],
+    )
+    dims = bbox_for_section(sec)
+    assert dims is not None
+    # y extents: layer [-0.15, 0.15] (wider than patch [-0.10, 0.10]) → 0.30
+    # z extents: patch [-0.10, 0.10] + layer z=0.12 → [-0.10, 0.12] → 0.22
+    # plus the bar radius sqrt(bar_area / pi) on each rebar side.
+    r = math.sqrt(1e-4 / math.pi)
+    assert dims[0] == pytest.approx(0.30 + 2 * r)
+    assert dims[1] == pytest.approx(0.22 + r)
+
+
+def test_empty_fiber_section_returns_none() -> None:
+    sec = FiberSection(id=1)
+    assert bbox_for_section(sec) is None