refactor: angleage

packages/math/src/math.js

@@ -51,7 +51,9 @@ export const PI_180 = Math.PI / 180;
 export const add = (l, r) => l + r;
 export const div = (l, r) => l / r;
 export const frac = (number) => number % 1;
-export const fromRad = (r) => (r % (Math.PI * 2)) / PI_180;
+export const angleFromRad = (r) => (
+  (360 + ((2 * Math.PI - (r + HALF_PI)) % (Math.PI * 2)) / -PI_180) % 360
+);
 export const mul = (l, r) => l * r;
 export const normalizeAngleRange = (min, max) => {
   /* eslint-disable no-param-reassign */
@@ -82,6 +84,30 @@ export const toRad = (a) => (a % 360) * PI_180;
 export function describe() {
   return {
     children: {
+      add: {
+        label: 'Add',
+        type: 'number',
+        args: [
+          {
+            label: 'lhs',
+            type: 'number',
+          },
+          {
+            label: 'rhs',
+            type: 'number',
+          },
+        ],
+      },
+      angleFromRad: {
+        label: 'Angle from radians',
+        type: 'number',
+        args: [
+          {
+            label: 'Operand',
+            type: 'number',
+          },
+        ],
+      },
       floor: {
         label: 'Floor',
         type: 'number',
@@ -106,6 +132,20 @@ export function describe() {
           },
         ],
       },
+      sub: {
+        label: 'Sub',
+        type: 'number',
+        args: [
+          {
+            label: 'lhs',
+            type: 'number',
+          },
+          {
+            label: 'rhs',
+            type: 'number',
+          },
+        ],
+      },
     },
     type: 'object',
   };

packages/math/src/vector/vector.js

@@ -388,6 +388,16 @@ export function describe() {
           },
         ],
       },
+      toRadians: {
+        type: 'number',
+        label: 'To radians',
+        args: [
+          {
+            label: 'Vector',
+            type: 'vector',
+          },
+        ],
+      },
       sub: {
         type: 'vector',
         label: '$1 minus $2',

packages/math/test/math.js

@@ -0,0 +1,11 @@
+import {expect} from 'chai';
+
+import {angleFromRad, HALF_PI, PI} from '../src/math';
+
+it('can translate radians into degrees', () => {
+  expect(angleFromRad(0)).to.equal(90);
+  expect(angleFromRad(HALF_PI)).to.equal(180);
+  expect(angleFromRad(PI)).to.equal(270);
+  expect(angleFromRad(PI + HALF_PI)).to.equal(0);
+  expect(angleFromRad(2 * PI)).to.equal(90);
+});