Confusing SignedDistance calculation in QuadraticSegment::signedDistance

[jkb0o]

Hello! I'm trying to port you amazing library to the pure rust (almost brainlessly) and I found confusing part in the SignedDistance calculation:

msdfgen/core/edge-segments.cpp

Lines 183 to 188 in eeec8f2

	if (param >= 0 && param <= 1)
	return SignedDistance(minDistance, 0);
	if (param < .5)
	return SignedDistance(minDistance, fabs(dotProduct(direction(0).normalize(), qa.normalize())));
	else
	return SignedDistance(minDistance, fabs(dotProduct(direction(1).normalize(), (p[2]-origin).normalize())));

There are cross if/else conditions. Looks like the first if should test for the outer bounds of 0..1 or the second if should test against 0/1. The same is valid for the QubicSegment as well.

I not really deep into math, I do not understand everything, so I would appreciate any explanation of this condition.

Thank you for a great job!

[Chlumsky]

I'm not sure I understand your point. The first condition checks if param is between 0 and 1. Otherwise, the second condition splits the remaining possibilities - param lower than 0 or greater than 1. It does so by comparing to 0.5, the value in the middle, but any value between 0 and 1 would work.

[jkb0o]

Yeah, now it looks super natural and I wondered why I was confused. Thank you! Sorry for disturbing.