feat(math): lerp and remap utils (#31)

Author: osalinasv

src/math.test.ts

@@ -1,5 +1,5 @@
 import{expect,it}from'vitest'
-import{sum}from'./math'
+import{lerp,remap,sum}from'./math'
 
 it('sum',()=>{
 expect(sum(1,2,3)).toEqual(6)
@@ -9,3 +9,27 @@ it('sum', () => {
 // @ts-expect-error
 expect(sum(1,2,[1,2,3])).toEqual(9)
 })
+
+it('lerp',()=>{
+expect(lerp(0,2,0)).toEqual(0)
+expect(lerp(0,2,1)).toEqual(2)
+expect(lerp(0,2,0.5)).toEqual(1)
+
+expect(lerp(-10,10,0.5)).toEqual(0)
+expect(lerp(10,-10,0.5)).toEqual(0)
+
+expect(lerp(0,1,-1.5)).toEqual(0)
+expect(lerp(0,1,2.5)).toEqual(1)
+})
+
+it('remap',()=>{
+expect(remap(0,0,1,0,10)).toEqual(0)
+expect(remap(1,0,1,0,10)).toEqual(10)
+expect(remap(0.5,0,1,0,10)).toEqual(5)
+
+expect(remap(0.5,-1,1,0,1)).toEqual(0.75)
+expect(remap(0.25,0,1,-1,1)).toEqual(-0.5)
+
+expect(remap(2,0,1,5,10)).toEqual(10)
+expect(remap(-1,0,1,5,10)).toEqual(5)
+})

src/math.ts

@@ -7,3 +7,32 @@ export function clamp(n: number, min: number, max: number) {
 exportfunctionsum(...args: number[]|number[][]){
 returnflattenArrayable(args).reduce((a,b)=>a+b,0)
 }
+
+/**
+ * Linearly interpolates between `min` and `max` based on `t`
+ *
+ * @category Math
+ * @param t The interpolation value clamped between 0 and 1
+ * @example
+ * ```
+ * const value = lerp(0, 2, 0.5) // value will be 1
+ * ```
+ */
+exportfunctionlerp(min: number,max: number,t: number){
+constinterpolation=clamp(t,0.0,1.0)
+returnmin+(max-min)*interpolation
+}
+
+/**
+ * Linearly remaps a clamped value from its source range [`inMin`, `inMax`] to the destination range [`outMin`, `outMax`]
+ *
+ * @category Math
+ * @example
+ * ```
+ * const value = remap(0.5, 0, 1, 200, 400) // value will be 300
+ * ```
+ */
+exportfunctionremap(n: number,inMin: number,inMax: number,outMin: number,outMax: number){
+constinterpolation=(n-inMin)/(inMax-inMin)
+returnlerp(outMin,outMax,interpolation)
+}