Add constant, linear and TCB spline formula operations

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/tests/test_formula.py b/tests/test_formula.py
index 72f41ea..7440681 100644
--- a/tests/test_formula.py
+++ b/tests/test_formula.py
@@ -130,3 +130,41 @@ class GraphTest(unittest.TestCase):
         g.add_formula("c", [push("a"), push("a"), {"op": "add"}])
         g.add_formula("d", [push("b"), push("c"), {"op": "add"}])
         self.assertEqual(g.evaluate()["d"], 3)
+
+
+from generat3d.formula import spline
+
+
+def spline_ops(kind, knots):
+    return ([{"op": "push", "key": "a"}] + [val(k) for k in knots]
+            + [val(len(knots)), {"op": kind}])
+
+
+class SplineTest(unittest.TestCase):
+    LINE = [[0, 0], [1, 1], [2, 2], [3, 3]]
+
+    def test_outside_range_holds_ends(self):
+        for kind in ("spline_constant", "spline_linear", "spline_tcb"):
+            self.assertEqual(spline(kind, -1, self.LINE), 0)
+            self.assertEqual(spline(kind, 9, self.LINE), 3)
+
+    def test_constant(self):
+        self.assertEqual(spline("spline_constant", 1.7, [[0, 5], [1, 6], [2, 7]]), 6)
+
+    def test_linear(self):
+        self.assertAlmostEqual(spline("spline_linear", 0.25, [[0, 0], [1, 4]]), 1.0)
+
+    def test_tcb_hits_knots(self):
+        knots = [[0, 0, 0, 0, 0], [1, 3, 0, 0, 0], [2, 1, 0, 0, 0]]
+        self.assertEqual(spline("spline_tcb", 1, knots), 3)
+
+    def test_tcb_zero_params_is_catmull_rom(self):
+        knots = [k + [0, 0, 0] for k in self.LINE]
+        self.assertAlmostEqual(spline("spline_tcb", 1.5, knots), 1.5)
+
+    def test_spline_in_graph(self):
+        g = Graph()
+        g.add_prop("a", 0.5)
+        g.add_prop("b")
+        g.add_formula("b", spline_ops("spline_linear", [[0, 0], [1, 10]]))
+        self.assertAlmostEqual(g.evaluate()["b"], 5.0)