使用JavaScript绘制正弦波

Question

I am working on creating a simple snow simulation, but I am failing horribly on the math. Basically, when a snowflake is initialized, it's x position is set randomly somewhere on the svg canvas. Then from there, it falls straight down. It should be simulating a sine wave (the x coordinates should move like a sine wave).

I haven't done trig since last year so i'm a bit rusty. Math.sin() takes radians I believe, so I multiply by 180, then divide by pi to convert to degrees?

Assume x is the current x position of a snowflake, and width is the width of the canvas.

x += (Math.sin(((x/width)*(180/Math.PI)))*width)

It kind of works, but it is all over the place. I have a vague idea of what i'm doing, but I can't seem to push the math from my brain to code.

Here's a JSFiddle:

What am I doing incorrectly?

Answer 1

It should be:

x += A*Math.sin(F*(y/Height)*2*Math.PI);

where A is the amplitude, ie how many pixels you want the flake to shift left and right (note that total shift will be 2*A). F is the frequency, or how often you want the flake to shift left and right (I'd set it at random between 2 and 10 for each flake).