N 体重力/太阳系 Javascript 模拟

美好的一天，我正在尝试用 javascript 创建一个简单的 2D 太阳系模型，但是在理解如何计算下一帧行星的位置以及其他一些我将详细介绍的部分时遇到了一些麻烦随着很快。

看完这个非常好的视频和他的一大堆其他视频后，我制作了一个快速的 MS 绘画图像来尝试简化我的情况。在第二个场景中，您可以看到新位置是使用速度、引力和这两个“方向”之间的角度来计算的？

我无法理解如何解决这一切。

Below is a JS fiddle of my code. You'll notice I'm trying my best to use real NASA given data to keep it accurate.

You'll want to look specifically at lines 138 which is where all the calculations for its next move are made.

https://jsfiddle.net/c8eru7mk/9/

attraction: function(p2) {
    // Distance to other body
    var dx = p2.position.x - this.position.x;
    var dy = p2.position.y - this.position.y;
    var d = Math.sqrt(dx ** 2 + dy ** 2); // Possibly correct

    // Force of attracrtion
    this.f = G * (this.mass * p2.mass) / (d ** 2); // Possibly Correct

    // Direction of force, If you read it hard enough you should be able to hear my screams of pain
    // Not sure if this is correct, most likely not.
    var theta = Math.atan2(dy, dx);
    var fx = Math.cos(theta) * this.f;
    var fy = Math.sin(theta) * this.f;

    this.velocity.x += fx / this.mass;
    this.velocity.y += fy / this.mass;

    this.position.x += this.velocity.x;
    this.position.y += this.velocity.y;
}

The problems I'm currently facing are

• If I am to use NASA values, the distance between planets is so big, they won't fit on the screen, and I can't simply scale the distances down by multiplying them by 0.0002 or whatever, as that'll mess with the gravitational constant, and the simulation will be completely off.
• I have no idea how to caluclate the next position and my brain has imploded several times this past week trying to attempt it several times.
• I have no idea on how to check if my configuration data of planets is wrong, or if the simulation is wrong, so I'm pretty much just guessing.

This is also my first time actually coding anything more complex than a button in javascript too, so feedback on code layout and whatnot is welcome!

Many thanks