body 不遵守低速反射定律

Question

我正在尝试模拟一个球在游泳池周围弹跳 table 并且遇到了一个问题。（视图是从上面俯视table）。

我总是希望球能根据反射定律反弹出边界。 Angle of incidence = angle of reflection

在右侧边界的模拟结束时，球似乎沿着它滚动。为什么不遵循反射定律？

    var Engine = Matter.Engine,
    Render = Matter.Render,
    World = Matter.World,
    Bodies = Matter.Bodies,
    Body = Matter.Body,
    Vector = Matter.Vector,
    Events = Matter.Events;

// create an engine
var engine = Engine.create();

var canvas = document.getElementById('canvas');

engine.world.gravity.y = 0; // gravity not needed in this app

// create a renderer
var render = Render.create({
    element: document.body,
    canvas: canvas,
    engine: engine,
    options: {wireframes: true}
});

var ball_options = {
    density: 0.04,
  restitution: 1,// 0 = no bouncing, 1 = 100% of kinetic energy bounce back
  friction: 0,
  frictionAir: 0.05,
  inertia: Infinity
};

var boundary_options = {
  isStatic: true
};

var ball = Bodies.circle(100, 150, 11, ball_options);

var boundary_left = Bodies.rectangle(10, 160, 100, 200, boundary_options);
var boundary_right = Bodies.rectangle(300, 160, 100, 200, boundary_options);
var boundary_top = Bodies.rectangle(150, 10, 200, 100, boundary_options);
var boundary_bottom = Bodies.rectangle(150, 300, 200, 100, boundary_options);

// add all of the bodies to the world
World.add(engine.world, [
    boundary_left,
  boundary_right,
  boundary_top,
  boundary_bottom,
  ball
  ]);

render.options.height = 300;
canvas.height = 300;
Engine.run(engine);
Render.run(render);

Body.applyForce(ball, { x: 0, y: 0 }, { x: 0.2, y: 0.5 });

Answer 1

电脑里的数字不是实数；他们是interests。 'float' 表示 'number like float'。这就是为什么 x 轴上的速度不会连续减小到 0 的原因。在代码中，x 轴的初始速度小于 y 轴的 1。所以 'Discrete effect' 出现在 x 轴上。当恢复几乎为 1 时，您会感觉像真正的球。谢谢。

Answer 2

我已经在库创建者的帮助下解决了这个问题。

https://jsfiddle.net/8exLLLv6/55/

将以下内容添加到我的代码中解决了问题：

Matter.Resolver._restingThresh = 0.1;

有关详细信息，请参阅 gibhub 页面。

body 不遵守低速反射定律

body not respecting the law of reflection at lower speeds

javascript

physics-engine

matter.js