[fn-mote]

Spoiler: divide and conquer is the way to go. Adding paths one at a time to a massive union is slow.

This seem like more of a surprise to the author than it was for me.

I’d say the takeaway is that treating everything like a black box doesn’t produce good results (sometimes). And not knowing enough to open the box completely leaves you with a lot of unknowns, surprises, and loose ends. But hey, figuring this stuff out is why we get paid the $$$.

Sometimes it would help to read a book or consult someone more knowledgeable though.

[dwattttt]

> When a rabbit is placed inside the Black Box and vanishes on cue, it is the audience’s privilege to simply ooh and aah in wonderment. But we who step on stage should know how the trick is done. The loss of innocence is the price of applause.

From the very good, yet sadly HTTP http://thecodelesscode.com/case/195

[dsign]

> I’d say the takeaway is that treating everything like a black box doesn’t produce good results (sometimes). And not knowing enough to open the box completely leaves you with a lot of unknowns, surprises, and loose ends. But hey, figuring this stuff out is why we get paid the $$$.

To add a little bit of nuance to your comment, I've to say that computational geometry algorithms are incredibly human-effort-intensive. Treating their implementations as a black-box could be an incredible time-saver. In my experience however, that particular black box tends to fail when least one needs it, and then one is left with inscrutable pieces. Often the "least bad" approach is to learn how polygon/polyline composition works and implement it oneself. It will be buggy and crappy (at first) but it won't break in cryptic ways. Budget a couple of months for the learning and initial implementation though, and be most wary of floating point and God coming in the night to mess with your code and put new bugs.

[vg_head]

> This seem like more of a surprise to the author than it was for me.

The bigger surprise for me was that the path builder is slower than doing divide and conquer, given that it's optimized for doing union on everything.

> Sometimes it would help to read a book or consult someone more knowledgeable though.

I'd be happy to receive suggestions!