feat(math): add smoothStep01/smootherStep01()

thi-ng · Jul 11, 2023 · 152f93c · 152f93c
1 parent e0fe047
commit 152f93c
Showing 1 changed file with 27 additions and 9 deletions.
diff --git a/packages/math/src/step.ts b/packages/math/src/step.ts
@@ -1,4 +1,4 @@
-import type { FnN2, FnN3 } from "@thi.ng/api";
+import type { FnN, FnN2, FnN3 } from "@thi.ng/api";
 import { clamp01 } from "./interval.js";
 
 /**
@@ -13,27 +13,45 @@ export const step: FnN2 = (edge, x) => (x < edge ? 0 : 1);
 /**
  * GLSL-style smoothStep threshold function.
  *
+ * @remarks
+ * Also see {@link smoothStep01}, {@link smootherStep}.
+ *
  * @param edge - lower threshold
  * @param edge2 - upper threshold
  * @param x - test value
  * @returns 0, if `x < edge1`, 1 if `x > edge2`, else S-curve polynomial interpolation
  */
-export const smoothStep: FnN3 = (edge, edge2, x) => {
-	x = clamp01((x - edge) / (edge2 - edge));
-	return (3 - 2 * x) * x * x;
-};
+export const smoothStep: FnN3 = (edge, edge2, x) =>
+	smoothStep01(clamp01((x - edge) / (edge2 - edge)));
+
+/**
+ * Specialized version of {@link smoothStep}, assuming edges are 0/1
+ * respectively and `x` is in [0..1]. No clamping performed.
+ *
+ * @param x
+ */
+export const smoothStep01: FnN = (x) => x * x * (3 - 2 * x);
 
 /**
  * Similar to {@link smoothStep} but using different, higher degree polynomial.
  *
+ * @remarks
+ * Also see {@link smootherStep01}.
+ *
  * @param edge -
  * @param edge2 -
  * @param x -
  */
-export const smootherStep: FnN3 = (edge, edge2, x) => {
-	x = clamp01((x - edge) / (edge2 - edge));
-	return x * x * x * (x * (x * 6 - 15) + 10);
-};
+export const smootherStep: FnN3 = (edge, edge2, x) =>
+	smootherStep01(clamp01((x - edge) / (edge2 - edge)));
+
+/**
+ * Specialized version of {@link smootherStep}, assuming edges are 0/1
+ * respectively and `x` is in [0..1]. No clamping performed.
+ *
+ * @param x
+ */
+export const smootherStep01: FnN = (x) => x * x * x * (x * (x * 6 - 15) + 10);
 
 /**
  * Exponential ramp with variable shape