@technobuddha/library/src/lerp.test.ts

A large library of useful functions

import { lerp } from './lerp.ts';

describe('lerp', () => {
  test('converts left to right range', () => {
    expect(lerp(0, 10, 0.0)).toBeCloseTo(0);
    expect(lerp(0, 10, 0.1)).toBeCloseTo(1);
    expect(lerp(0, 10, 0.2)).toBeCloseTo(2);
    expect(lerp(0, 10, 0.3)).toBeCloseTo(3);
    expect(lerp(0, 10, 0.4)).toBeCloseTo(4);
    expect(lerp(0, 10, 0.5)).toBeCloseTo(5);
    expect(lerp(0, 10, 0.6)).toBeCloseTo(6);
    expect(lerp(0, 10, 0.7)).toBeCloseTo(7);
    expect(lerp(0, 10, 0.8)).toBeCloseTo(8);
    expect(lerp(0, 10, 0.9)).toBeCloseTo(9);
    expect(lerp(0, 10, 1.0)).toBeCloseTo(10);
  });

  test('converts right to left range', () => {
    expect(lerp(0, -10, 0.0)).toBeCloseTo(-0);
    expect(lerp(0, -10, 0.1)).toBeCloseTo(-1);
    expect(lerp(0, -10, 0.2)).toBeCloseTo(-2);
    expect(lerp(0, -10, 0.3)).toBeCloseTo(-3);
    expect(lerp(0, -10, 0.4)).toBeCloseTo(-4);
    expect(lerp(0, -10, 0.5)).toBeCloseTo(-5);
    expect(lerp(0, -10, 0.6)).toBeCloseTo(-6);
    expect(lerp(0, -10, 0.7)).toBeCloseTo(-7);
    expect(lerp(0, -10, 0.8)).toBeCloseTo(-8);
    expect(lerp(0, -10, 0.9)).toBeCloseTo(-9);
    expect(lerp(0, -10, 1.0)).toBeCloseTo(-10);
  });

  test('converts negative portion', () => {
    expect(lerp(0, 10, -0.0)).toBeCloseTo(-0);
    expect(lerp(0, 10, -0.1)).toBeCloseTo(-1);
    expect(lerp(0, 10, -0.2)).toBeCloseTo(-2);
    expect(lerp(0, 10, -0.3)).toBeCloseTo(-3);
    expect(lerp(0, 10, -0.4)).toBeCloseTo(-4);
    expect(lerp(0, 10, -0.5)).toBeCloseTo(-5);
    expect(lerp(0, 10, -0.6)).toBeCloseTo(-6);
    expect(lerp(0, 10, -0.7)).toBeCloseTo(-7);
    expect(lerp(0, 10, -0.8)).toBeCloseTo(-8);
    expect(lerp(0, 10, -0.9)).toBeCloseTo(-9);
    expect(lerp(0, 10, -1.0)).toBeCloseTo(-10);
  });

  test('zero width range', () => {
    expect(lerp(0, 0, 0.0)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.1)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.2)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.3)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.4)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.5)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.6)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.7)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.8)).toBeCloseTo(0);
    expect(lerp(0, 0, 0.9)).toBeCloseTo(0);
    expect(lerp(0, 0, 1.0)).toBeCloseTo(0);
  });
});