在使用matter.js的plinko游戏中，如何让小球始终落在预定的位置

Question

以下面的代码为例。我怎样才能让球每次都看似随机地落入底部的第三个空间位置？

我能想到的就是在小球下落的过程中不断判断它的碰撞位置，让小球朝着目标运动，但是如何让运动的过程显得自然随机，难倒我了

// create an engine
const engine = Engine.create()

// create a renderer
const render = Render.create({
  element: document.body,
  engine: engine
})
// create flanges
const fOptions = {
  isStatic: true
}
const flanges = [
  //row one
  Bodies.polygon(45, 150, 3, 20, fOptions),
  Bodies.polygon(100, 250, 3, 20, fOptions),
  Bodies.polygon(60, 350, 3, 20, fOptions),
  Bodies.polygon(100, 450, 3, 20, fOptions),
  //row two
  Bodies.polygon(150, 150, 3, 20, fOptions),
  Bodies.polygon(200, 250, 3, 20, fOptions),
  Bodies.polygon(150, 350, 3, 20, fOptions),
  Bodies.polygon(200, 450, 3, 20, fOptions),
  //row three
  Bodies.polygon(250, 150, 3, 20, fOptions),
  Bodies.polygon(300, 250, 3, 20, fOptions),
  Bodies.polygon(250, 350, 3, 20, fOptions),
  Bodies.polygon(300, 450, 3, 20, fOptions),
  //row four
  Bodies.polygon(350, 150, 3, 20, fOptions),
  Bodies.polygon(400, 250, 3, 20, fOptions),
  Bodies.polygon(350, 350, 3, 20, fOptions),
  Bodies.polygon(400, 450, 3, 20, fOptions),
  //row five
  Bodies.polygon(450, 150, 3, 20, fOptions),
  Bodies.polygon(500, 250, 3, 20, fOptions),
  Bodies.polygon(450, 350, 3, 20, fOptions),
  Bodies.polygon(500, 450, 3, 20, fOptions),
  //row six
  Bodies.polygon(550, 150, 3, 20, fOptions),
  Bodies.polygon(600, 250, 3, 20, fOptions),
  Bodies.polygon(550, 350, 3, 20, fOptions),
  Bodies.polygon(600, 450, 3, 20, fOptions),
  //row seven
  Bodies.polygon(650, 150, 3, 20, fOptions),
  Bodies.polygon(700, 250, 3, 20, fOptions),
  Bodies.polygon(650, 350, 3, 20, fOptions),
  Bodies.polygon(700, 450, 3, 20, fOptions),
  //row 8
  Bodies.polygon(755, 150, 3, 20, fOptions),
  Bodies.polygon(740, 350, 3, 20, fOptions)
]
for (i = 0; i < flanges.length; i++) {
  World.add(engine.world, [flanges[i]])
  Body.setAngle(flanges[i], 16.23)
}
//create catches
const cOptions = {
  isStatic: true
}
const catches = [Bodies.rectangle(40, 560, 2, 40, cOptions)]
xasx = 82
for (v = 0; v < 20; v++) {
  catches.push(Bodies.rectangle(xasx, 560, 2, 40, cOptions))
  World.add(engine.world, [catches[v]])
  xasx = xasx + 45
}
// create disk
let disk = []
let count = 0
const dOptions = {
  friction: 0.2,
  restitution: 1
}

function addD() {
  disk.push(Bodies.circle(event.offsetX, event.offsetY, 20, dOptions))
  World.add(engine.world, [disk[count]])
  count++
}
// create ground sky and walls
const ground = Bodies.rectangle(400, 610, 810, 60, {
  isStatic: true
})
const leftWall = Bodies.rectangle(0, 305, 2, 810, {
  isStatic: true
})
const righttWall = Bodies.rectangle(800, 305, 2, 810, {
  isStatic: true
})
const sky = Bodies.rectangle(400, 0, 810, 2, {
  isStatic: true
})
// add all of the bodies to the world
World.add(engine.world, [sky, righttWall, leftWall, ground])

// run the engine
Engine.run(engine)

// run the renderer
Render.run(render)

让球每次看起来总是随机落入底部的第三个空间位置