@thi.ng/grid-iterators/circle.js

2D grid and shape iterators w/ multiple orderings

import { asInt } from "@thi.ng/api/typedarray";
import { clipped, intersectRectCircle } from "./clipping.js";
import { hline } from "./hvline.js";
function* circle(cx, cy, r, fill = true) {
  [cx, cy, r] = asInt(cx, cy, r);
  if (r < 1) return;
  let x = 0;
  let y = r;
  let y2 = r * r;
  let sum = y2 + r;
  let dx2 = 1;
  let dy2 = 2 * r - 1;
  while (x <= y) {
    if (fill) {
      yield* hline(cx - y, cy + x, y << 1);
      if (x) yield* hline(cx - y, cy - x, y << 1);
    } else {
      yield [cx - y, cy + x];
      if (y) yield [cx + y, cy + x];
      if (x) {
        yield [cx - y, cy - x];
        if (y) yield [cx + y, cy - x];
      }
      if (x !== y) {
        yield [cx - x, cy - y];
        if (x) yield [cx + x, cy - y];
        if (y) {
          yield [cx - x, cy + y];
          if (x) yield [cx + x, cy + y];
        }
      }
    }
    sum -= dx2;
    if (sum <= y2) {
      if (fill && x !== y) {
        yield* hline(cx - x, cy - y, x << 1);
        if (y) yield* hline(cx - x, cy + y, x << 1);
      }
      y--;
      y2 -= dy2;
      dy2 -= 2;
    }
    x++;
    dx2 += 2;
  }
}
const circleClipped = (cx, cy, r, left, top, right, bottom, fill = true) => {
  return intersectRectCircle(left, top, right, bottom, cx, cy, r) ? clipped(circle(cx, cy, r, fill), left, top, right, bottom) : void 0;
};
export {
  circle,
  circleClipped
};