test: unit tests for Line2d

src/index.ts

@@ -1,6 +1,7 @@
 export * from "./vec2d";
 export * from "./curve-base2d";
 export * from "./curve2d";
+export * from "./line2d";
 export * from "./arc2d";
 export * from "./bezier2d";
 export * from "./catmull2d";

src/line2d.ts

@@ -31,7 +31,7 @@ export class Line2d extends CurveBase2d {
     return this.start.lerp(this.end, t);
   }
 
-  public getSegment(tStart: number, tEnd: number): CurveBase2d {
+  public getSegment(tStart: number, tEnd: number) {
     return new Line2d(this.get(tStart), this.get(tEnd));
   }
 

test/line2d.test.ts

@@ -0,0 +1,73 @@
+import { Line2d, Vec2d } from "src/index";
+import { vectorRoughlyEquals } from "test/util";
+
+describe("Line2d", () => {
+  it("should get points along a line", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 10, y: 2 });
+    vectorRoughlyEquals(line.get(0), new Vec2d(0, 0));
+    vectorRoughlyEquals(line.get(0.2), new Vec2d(2, 0.4));
+    vectorRoughlyEquals(line.get(0.4), new Vec2d(4, 0.8));
+    vectorRoughlyEquals(line.get(0.6), new Vec2d(6, 1.2));
+    vectorRoughlyEquals(line.get(0.8), new Vec2d(8, 1.6));
+    vectorRoughlyEquals(line.get(1), new Vec2d(10, 2));
+  });
+  it("should calculate the length of a line", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 3, y: 4 });
+    expect(line.length()).toBeCloseTo(5, 6);
+  });
+  it("should return a pass-through percentage fn", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 3, y: 4 });
+    const fn = line.getPercentageFn();
+    for (let i = 0; i <= 1; i += 1) expect(fn(i)).toBeCloseTo(i, 6);
+  });
+  it("should alias getByPercent to get", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 10, y: 2 });
+    vectorRoughlyEquals(line.getByPercent(0), new Vec2d(0, 0));
+    vectorRoughlyEquals(line.getByPercent(0.2), new Vec2d(2, 0.4));
+    vectorRoughlyEquals(line.getByPercent(0.4), new Vec2d(4, 0.8));
+    vectorRoughlyEquals(line.getByPercent(0.6), new Vec2d(6, 1.2));
+    vectorRoughlyEquals(line.getByPercent(0.8), new Vec2d(8, 1.6));
+    vectorRoughlyEquals(line.getByPercent(1), new Vec2d(10, 2));
+  });
+  it("should clone a line", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 3, y: 4 });
+    const copy = line.clone();
+    vectorRoughlyEquals(line.start, copy.start);
+    vectorRoughlyEquals(line.end, copy.end);
+  });
+  it("should calculate a subsegment of a line", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 10, y: 2 });
+    const segment = line.getSegment(0.2, 0.6);
+    vectorRoughlyEquals(segment.start, new Vec2d(2, 0.4));
+    vectorRoughlyEquals(segment.end, new Vec2d(6, 1.2));
+  });
+  it("should reverse a line", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 3, y: 4 });
+    const copy = line.reverse();
+    vectorRoughlyEquals(line.start, copy.end);
+    vectorRoughlyEquals(line.start, copy.end);
+  });
+  it("should rotate a line around a pivot", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 3, y: 4 });
+    const angle = 1;
+    const origin = new Vec2d(12, -0.3);
+    const rotated = line.rotate(angle, origin);
+    for (let i = 0; i <= 1; i += 0.1)
+      vectorRoughlyEquals(rotated.get(i), line.get(i).rotate(angle, origin));
+  });
+  it("should scale a line from a given origin", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 3, y: 4 });
+    const factor = 1.8;
+    const origin = new Vec2d(12, -0.3);
+    const scaled = line.scale(factor, origin);
+    for (let i = 0; i <= 1; i += 0.1)
+      vectorRoughlyEquals(scaled.get(i), line.get(i).scale(factor, origin));
+  });
+  it("should translate a line by a given offset", () => {
+    const line = new Line2d({ x: 0, y: 0 }, { x: 3, y: 4 });
+    const offset = new Vec2d(-2.19, 555.003);
+    const translated = line.translate(offset);
+    for (let i = 0; i <= 1; i += 0.1)
+      vectorRoughlyEquals(translated.get(i), line.get(i).add(offset));
+  });
+});