Calculate ThreeJS viewport at depth

calculate-three-viewport-at-depth.ts

import { PerspectiveCamera } from "three";

export const getDepthPositionMult = (depth: number, camera: PerspectiveCamera) => {
  const { aspect, fov } = camera;
  const vFov = (fov * Math.PI) / 180;

  const planeHeightAtDistance =
    2 * Math.tan(vFov / 2) * (depth + camera.position.z);
  const planeWidthAtDistance = planeHeightAtDistance * aspect;

  return {
    width: planeWidthAtDistance,
    height: planeHeightAtDistance
  };
};