Added shape drawing and more vector helper functions

src/helpers/vector2.js

@@ -1,3 +1,5 @@
+import { toRadians } from "./shared";
+
 export function lengthSquared(p) {
   return p.x * p.x + p.y * p.y;
 }
@@ -8,7 +10,7 @@ export function length(p) {
 
 export function normalize(p) {
   const l = length(p);
-  return { x: p.x / l, y: p.y / l };
+  return divide(p, l);
 }
 
 export function dot(a, b) {
@@ -16,5 +18,55 @@ export function dot(a, b) {
 }
 
 export function subtract(a, b) {
-  return { x: a.x - b.x, y: a.y - b.y };
+  if (typeof b === "number") {
+    return { x: a.x - b, y: a.y - b };
+  } else {
+    return { x: a.x - b.x, y: a.y - b.y };
+  }
+}
+
+export function add(a, b) {
+  if (typeof b === "number") {
+    return { x: a.x + b, y: a.y + b };
+  } else {
+    return { x: a.x + b.x, y: a.y + b.y };
+  }
+}
+
+export function multiply(a, b) {
+  if (typeof b === "number") {
+    return { x: a.x * b, y: a.y * b };
+  } else {
+    return { x: a.x * b.x, y: a.y * b.y };
+  }
+}
+
+export function divide(a, b) {
+  if (typeof b === "number") {
+    return { x: a.x / b, y: a.y / b };
+  } else {
+    return { x: a.x / b.x, y: a.y / b.y };
+  }
+}
+
+export function rotate(point, origin, angle) {
+  const cos = Math.cos(toRadians(angle));
+  const sin = Math.sin(toRadians(angle));
+  const dif = subtract(point, origin);
+  return {
+    x: origin.x + cos * dif.x - sin * dif.y,
+    y: origin.y + sin * dif.x + cos * dif.y,
+  };
+}
+
+export function rotateDirection(direction, angle) {
+  return rotate(direction, { x: 0, y: 0 }, angle);
+}
+
+export function min(a) {
+  return a.x < a.y ? a.x : a.y;
+}
+
+export function max(a) {
+  return a.x > a.y ? a.x : a.y;
 }