lerp

1/**
2 * Performs linear interpolation between two numbers.
3 *
4 * @param a - The start value.
5 * @param b - The end value.
6 * @param t - A number between 0 and 1 indicating the interpolation factor.
7 * @returns The interpolated value.
8 */
9export function lerp(a: number, b: number, t: number): number {
10  return a + (b - a) * t;
11}

• Mathematically Standard

  Implements the canonical formula for linear interpolation, used widely in graphics, animation, and physics.

• Simple and Efficient

  A one-liner expression that offers excellent performance and high readability.

• Smooth Transitions

  Provides smooth value interpolation based on a normalized factor t, ideal for easing and blending.

• Precision Friendly

  Uses arithmetic directly rather than iterative methods, minimizing rounding errors.

Tests | Examples

1test('lerp - start point (t = 0)', () => {
2  expect(lerp(10, 20, 0)).toBe(10);
3});
4
5test('lerp - end point (t = 1)', () => {
6  expect(lerp(10, 20, 1)).toBe(20);
7});
8
9test('lerp - midpoint (t = 0.5)', () => {
10  expect(lerp(10, 20, 0.5)).toBe(15);
11});
12
13test('lerp - negative range', () => {
14  expect(lerp(-10, 10, 0.5)).toBe(0);
15});
16
17test('lerp - t > 1 (extrapolation)', () => {
18  expect(lerp(10, 20, 1.5)).toBe(25);
19});
20
21test('lerp - t < 0 (reverse extrapolation)', () => {
22  expect(lerp(10, 20, -0.5)).toBe(5);
23});

Common Use Cases

• Animation and Motion

  Interpolate between positions, rotations, or opacity values for smooth visual transitions.

• Game Development

  Move characters, cameras, or objects incrementally between states based on frame time or input.

• Data Smoothing and Blending

  Blend numerical values like temperatures, sensor data, or statistical readings.

• UI Transitions

  Gradually animate layout changes, progress bars, or theme adjustments over time.

• Procedural Generation

  Interpolate terrain heights, color gradients, or parameters during content generation.