[tantalor]

Is the author aware of https://developer.mozilla.org/en-US/docs/Web/API/CanvasRende...?

Use rotate(), translate(), and scale() instead of doing your own math.

[MJSplot_author]

Yes, but this is as simple. It's not really my maths, it's quite standard stuff.

I'm more excited about Path2D[0] becoming adopted by more browsers.

[0] https://developer.mozilla.org/en-US/docs/Web/API/Path2D