feat: center & localize

packages/math/src/vertice.js

@@ -89,6 +89,17 @@ export function bresenham([x1, y1], [x2, y2]) {
   return points;
 }
 
+export function center(vs) {
+  let cx = 0;
+  let cy = 0;
+  for (let i = 0; i < vs.length; ++i) {
+    const [x, y] = vs[i];
+    cx += x;
+    cy += y;
+  }
+  return Vector.scale([cx, cy], 1 / vs.length);
+}
+
 export function convexHull(vertices) {
   const scanner = new GrahamScan();
   for (let i = 0; i < vertices.length; i++) {
@@ -99,6 +110,15 @@ export function convexHull(vertices) {
     .map(({x, y}) => [x, y]);
 }
 
+export function localize(vs) {
+  const c = center(vs);
+  const localize = [];
+  for (let i = 0; i < vs.length; i++) {
+    localize[i] = Vector.sub(vs[i], c);
+  }
+  return [localize, c];
+}
+
 const c = [
   Vector.fromDirection(0),
   Vector.fromDirection(1),