Change SweepEvent structure

[mfogel]

Here's the relevant data structure as it exists now:

class SweepEvent {
  // a pointObject is a simple object of form {'x': <number>, 'y': <number>}
  // it is shared with normally one, but possibly more, other SweepEvents
  point: pointObject,

  // other stuff...
}

Here's the structure I think it would be worth testing:

class SweepEvent {
  // flattened point object. No more sharing of these coordinates between SweepEvents with
  // the same points - the raw numbers would just be repeated.
  x: <number>,
  y: <number>,

  // other stuff...
}

In addition, those point objects {'x': <number>, 'y': <number>} are passed to many helper methods/functions. Those could all be changed to just accept two separate arguments: x: <number> and y: <number>.

This could slightly increase memory usage (or decrease it? unsure how much overhead the small point objects introduce in JS) but would theoretically decrease the number of steps of dereferencing pointers to get at the values.

[mfogel]

After testing this out, it appears that this decreases performance in most cases. Re-using the point object is better than flattening it.

In fact, better to move all information shared between sweep events into a shared object. This means that the current structure:

class SweepEvent {
  point: {
    x: <number>,
    y: <number>
  }
  linkedEvents: [<SweepEvent>, ... ]
  segment: <Segment>
}

Would be more performant as:

class SweepEvent {
  point: {
    x: <number>,
    y: <number>,
    events: [<SweepEvent>, ... ]
  }
  segment: <Segment>
}