optimize utils.droots

[F-star]

No description provided.

[Pomax]

Please update your description to explain why you filed this and what you think the new code does that the old code doesn't.

PRs are absolutely welcome, but I need to know why you're suggesting these changes, because looking at what you changed this is almost certainly motivated by fixing a bug related to taking the square root of a negative number, so you'll have to include (or at the very least talk about) a test case where the current code fails, and this new code doesn't.

[F-star]

Hello, this is a small optimization.

I found that utils.droots() is executed when bezier.extrema() is called.

Sometimes, bezier.extrema() returns [NaN, NaN], which is then discarded in the filter method, like this:

result[dim] = result[dim].filter(function(t2) {
  return t2 >= 0 && t2 <= 1;
});

So I think we can optimize it.

When the square of the "delta of the quadratic formula" is negative, it means that the quadratic equation has no real roots, and sqrt will return NaN when the input is a negative number.

It's a good idea to return [] in advance.

utils.droots() is only executed by bezier.extrema(), so this change will not break any existing functionality.

[Pomax]

Cheers. Do you have an example curve/code snippet we can add to the tests for this?

[F-star]

Well, this is not a bug. bezier.extrema() returns the correct result every time.

I just made a small change to utils.droots() to ensure it does not return an array with NaN values.

new Bezier(
  [
    {
      x: 100,
      y: 206,
    },
    {
      x: 121,
      y: 47,
    },
    {
      x: 141,
      y: 273,
    },
    {
      x: 215,
      y: 348,
    },
  ]
).extrema()

The example above will get an array with NaN in the X dimension in the droots method, but bezier.extrema() will filter it. You can console.log before filter to find this case.