excalidraw/packages/math/angle.ts

import type {
  Degrees,
  GlobalPoint,
  LocalPoint,
  PolarCoords,
  Radians,
} from "./types";
import { PRECISION } from "./utils";

// TODO: Simplify with modulo and fix for angles beyond 4*Math.PI and - 4*Math.PI
export const normalizeRadians = (angle: Radians): Radians => {
  if (angle < 0) {
    return (angle + 2 * Math.PI) as Radians;
  }
  if (angle >= 2 * Math.PI) {
    return (angle - 2 * Math.PI) as Radians;
  }
  return angle;
};

/**
 * Return the polar coordinates for the given cartesian point represented by
 * (x, y) for the center point 0,0 where the first number returned is the radius,
 * the second is the angle in radians.
 */
export const cartesian2Polar = <P extends GlobalPoint | LocalPoint>([
  x,
  y,
]: P): PolarCoords => [Math.hypot(x, y), Math.atan2(y, x)];

export function degreesToRadians(degrees: Degrees): Radians {
  return ((degrees * Math.PI) / 180) as Radians;
}

export function radiansToDegrees(degrees: Radians): Degrees {
  return ((degrees * 180) / Math.PI) as Degrees;
}

/**
 * Determines if the provided angle is a right angle.
 *
 * @param rads The angle to measure
 * @returns TRUE if the provided angle is a right angle
 */
export function isRightAngleRads(rads: Radians): boolean {
  return Math.abs(Math.sin(2 * rads)) < PRECISION;
}