Add tests for spline repeater asset placement and terrain conforming

tests/domain/spline-repeaters.test.ts

@@ -0,0 +1,123 @@
+import { describe, expect, it } from "vitest";
+
+import { createScenePath } from "../../src/document/paths";
+import { createTerrain } from "../../src/document/terrains";
+import { deriveSplineRepeaterInstances } from "../../src/spline-corridor/spline-repeaters";
+
+describe("spline repeaters", () => {
+  it("places bundled corridor assets along paths without requiring roads", () => {
+    const path = createScenePath({
+      id: "path-repeater-no-road",
+      road: {
+        enabled: false
+      },
+      repeaters: [
+        {
+          id: "repeater-fence",
+          assetId: "fence_segment_wood_2m",
+          placement: "left",
+          offset: 1,
+          spacing: 2,
+          startInset: 0,
+          endInset: 0,
+          scale: 1,
+          randomScale: 0,
+          randomYawDegrees: 0,
+          yawOffsetDegrees: 0,
+          terrainConform: false,
+          heightOffset: 0,
+          alignToSpline: true,
+          seed: 7
+        }
+      ],
+      points: [
+        {
+          id: "point-a",
+          position: { x: 0, y: 0, z: 0 }
+        },
+        {
+          id: "point-b",
+          position: { x: 4, y: 0, z: 0 }
+        }
+      ]
+    });
+
+    const instances = deriveSplineRepeaterInstances({ path });
+
+    expect(instances).toHaveLength(3);
+    expect(instances.map((instance) => instance.position)).toEqual([
+      { x: 0, y: 0, z: 1 },
+      { x: 2, y: 0, z: 1 },
+      { x: 4, y: 0, z: 1 }
+    ]);
+    expect(instances.map((instance) => instance.yawDegrees)).toEqual([
+      90,
+      90,
+      90
+    ]);
+  });
+
+  it("deterministically applies terrain conforming and random variation", () => {
+    const terrain = createTerrain({
+      id: "terrain-repeater",
+      position: { x: 0, y: 1, z: 0 },
+      sampleCountX: 3,
+      sampleCountZ: 3,
+      cellSize: 1,
+      heights: [
+        0,
+        0,
+        0,
+        1,
+        1,
+        1,
+        2,
+        2,
+        2
+      ]
+    });
+    const path = createScenePath({
+      id: "path-repeater-terrain",
+      repeaters: [
+        {
+          id: "repeater-rocks",
+          assetId: "edge_small_rocks_a_2m",
+          placement: "right",
+          offset: 1,
+          spacing: 2,
+          randomScale: 0.2,
+          randomYawDegrees: 10,
+          terrainConform: true,
+          heightOffset: 0.25,
+          seed: 3
+        }
+      ],
+      points: [
+        {
+          id: "point-a",
+          position: { x: 0, y: 10, z: 1 }
+        },
+        {
+          id: "point-b",
+          position: { x: 2, y: 10, z: 1 }
+        }
+      ]
+    });
+
+    const first = deriveSplineRepeaterInstances({
+      path,
+      terrains: [terrain]
+    });
+    const second = deriveSplineRepeaterInstances({
+      path,
+      terrains: [terrain]
+    });
+
+    expect(first).toEqual(second);
+    expect(first).toHaveLength(2);
+    expect(first[0]?.position.y).toBe(1.25);
+    expect(first[1]?.position.y).toBe(1.25);
+    expect(first[0]?.scale).not.toBe(1);
+    expect(first[0]?.yawDegrees).not.toBe(90);
+  });
+});