React Native Accelerometer Maze: set up ball and goal

Set up ball in App.js

// App.js
const BALL_SIZE = Math.floor(width * .02);
const ballStartPoint = GetRandomPoint(GRID_X, GRID_Y);
const theBall = Matter.Bodies.circle(
  ballStartPoint.x,
  ballStartPoint.y,
  BALL_SIZE,
  {
    label: "ball"
  }
);

const GOAL_SIZE = Math.floor(width * .04); 
const goalPoint = GetRandomPoint(GRID_X, GRID_Y);
const goal = Matter.Bodies.rectangle(goalPoint.x, goalPoint.y, GOAL_SIZE, GOAL_SIZE, {
  isStatic: true,
  isSensor: true,
  label: 'goal'
});