Add tests for scene path resolution and sampling

tests/domain/scene-paths.test.ts

@@ -0,0 +1,130 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  createScenePath,
+  getScenePathLength,
+  resolveScenePath,
+  sampleResolvedScenePathPosition,
+  sampleResolvedScenePathTangent,
+  sampleScenePathPosition,
+  sampleScenePathTangent
+} from "../../src/document/paths";
+
+describe("scene paths", () => {
+  it("resolves linear segments and samples position and tangent by progress", () => {
+    const path = createScenePath({
+      id: "path-open",
+      points: [
+        {
+          id: "point-a",
+          position: {
+            x: 0,
+            y: 0,
+            z: 0
+          }
+        },
+        {
+          id: "point-b",
+          position: {
+            x: 0,
+            y: 0,
+            z: 3
+          }
+        },
+        {
+          id: "point-c",
+          position: {
+            x: 4,
+            y: 0,
+            z: 3
+          }
+        }
+      ]
+    });
+    const resolvedPath = resolveScenePath(path);
+
+    expect(getScenePathLength(path)).toBe(7);
+    expect(resolvedPath.totalLength).toBe(7);
+    expect(resolvedPath.segments).toHaveLength(2);
+    expect(sampleScenePathPosition(path, 0)).toEqual({
+      x: 0,
+      y: 0,
+      z: 0
+    });
+    expect(sampleScenePathTangent(path, 0)).toEqual({
+      x: 0,
+      y: 0,
+      z: 1
+    });
+    expect(sampleResolvedScenePathPosition(resolvedPath, 0.5)).toEqual({
+      x: 0.5,
+      y: 0,
+      z: 3
+    });
+    expect(sampleResolvedScenePathTangent(resolvedPath, 0.5)).toEqual({
+      x: 1,
+      y: 0,
+      z: 0
+    });
+    expect(sampleScenePathPosition(path, 1)).toEqual({
+      x: 4,
+      y: 0,
+      z: 3
+    });
+  });
+
+  it("supports looped paths and wraps progress 1 back to the first point", () => {
+    const path = createScenePath({
+      id: "path-loop",
+      loop: true,
+      points: [
+        {
+          id: "point-a",
+          position: {
+            x: 0,
+            y: 0,
+            z: 0
+          }
+        },
+        {
+          id: "point-b",
+          position: {
+            x: 2,
+            y: 0,
+            z: 0
+          }
+        },
+        {
+          id: "point-c",
+          position: {
+            x: 2,
+            y: 0,
+            z: 2
+          }
+        },
+        {
+          id: "point-d",
+          position: {
+            x: 0,
+            y: 0,
+            z: 2
+          }
+        }
+      ]
+    });
+    const resolvedPath = resolveScenePath(path);
+
+    expect(resolvedPath.segments).toHaveLength(4);
+    expect(resolvedPath.totalLength).toBe(8);
+    expect(sampleResolvedScenePathPosition(resolvedPath, 1)).toEqual({
+      x: 0,
+      y: 0,
+      z: 0
+    });
+    expect(sampleResolvedScenePathTangent(resolvedPath, 1)).toEqual({
+      x: 0,
+      y: 0,
+      z: -1
+    });
+  });
+});