feat(shader-ast-stdlib): add fitNorm()

packages/shader-ast-stdlib/src/math/fit.ts

@@ -35,7 +35,22 @@ export const fit = <T extends PrimTerm>(
 	b: T,
 	c: T,
 	d: T
-): Term<TermType<T>> => mix(c, d, div(sub(x, a), sub(b, a)));
+): Term<TermType<T>> => mix(c, d, fitNorm(x, a, b));
+
+/**
+ * Scales value `x` from closed interval [a,b] to closed [0,1] interval. No
+ * clamping performed.
+ *
+ * @param x
+ * @param a
+ * @param b
+ * @returns
+ */
+export const fitNorm = <T extends PrimTerm>(
+	x: T,
+	a: T,
+	b: T
+): Term<TermType<T>> => div(sub(x, a), sub(b, a));
 
 /**
  * Same as {@link fit}, but first clamps `x` to closed [a,b] interval.