New math functions

src/Math.ts

@@ -10,6 +10,27 @@ export const bin = (value: boolean): 0 | 1 => {
   return value ? 1 : 0;
 };
 
+/**
+ * @summary generate a step function by comparing two values
+ * @worklet
+ */
+export const step = (value: number, edge: number) => {
+  "worklet";
+  return value < edge ? 0 : 1;
+};
+
+/**
+ * @summary Perform Hermite interpolation between two values
+ * @worklet
+ */
+export const smoothstep = (value: number, edge0: number, edge1: number) => {
+  "worklet";
+  // Scale, bias and saturate x to 0..1 range
+  const x = clamp((value - edge0) / (edge1 - edge0), 0, 1);
+  // Evaluate polynomial
+  return x * x * (3 - 2 * x);
+};
+
 /**
  * Linear interpolation
  * @param value
@@ -218,3 +239,21 @@ export const cubicBezierYForX = (
     .filter((root) => root >= 0 && root <= 1)[0];
   return cubicBezier(t, a.y, b.y, c.y, d.y);
 };
+
+/**
+ * @summary Euclidean distance between two vectors
+ * @worklet
+ */
+export const dist = (v1: Vector, v2: Vector) => {
+  "worklet";
+  return Math.sqrt((v1.x - v2.x) ** 2 + (v1.y - v2.y) ** 2);
+};
+
+/**
+ * @summary Returns true if a approximates b. Default precision is 0.001
+ * @worklet
+ */
+export const approximates = (a: number, b: number, precision = 0.001) => {
+  "worklet";
+  return Math.abs(a - b) <= precision;
+};

src/__tests__/Math.test.ts

@@ -8,6 +8,10 @@ import {
   toRad,
   toDeg,
   cubicBezierYForX,
+  dist,
+  approximates,
+  step,
+  smoothstep,
 } from "../Math";
 import { vec } from "../Vectors";
 
@@ -74,3 +78,26 @@ test("cubicBezierYForX2()", () => {
   const d = vec.create(227, 89);
   expect(Math.round(cubicBezierYForX(x, a, b, c, d))).toBe(y);
 });
+
+test("dist()", () => {
+  const v1 = { x: 0, y: 0 };
+  const v2 = { x: 100, y: 100 };
+  expect(dist(v1, v2)).toBe(Math.sqrt(100 ** 2 + 100 ** 2));
+});
+
+test("approximates()", () => {
+  expect(approximates(1, 1)).toBe(true);
+  expect(approximates(1, 1.001)).toBe(true);
+  expect(approximates(1, 1.0011)).toBe(false);
+  expect(approximates(1, 2, 1)).toBe(true);
+});
+
+test("step()", () => {
+  expect(step(1.5, 1)).toBe(1);
+  expect(step(0.5, 1)).toBe(0);
+});
+
+test("smoothstep()", () => {
+  expect(smoothstep(1.5, 1, 2)).toBe(0.5);
+  expect(smoothstep(0.5, 1, 2)).toBe(0);
+});