surface distance to the user for missed guesses

[michaelkirk]

When I guess incorrectly Then I should see a hint telling me how far away I am.

"Nope. You're 2.3 miles away."

or...

"Close! You're a 100 yards away."

Note that there already is a "distance" field used to determine if someone is "close enough" to be at the right spot, but I never determined what units this "distance" metric is in - I'm just using some build in functionality of RGEO/postgis. I have verified that it is not a simple multiple of the haversine distance e.g. as computed here: http://www.movable-type.co.uk/scripts/latlong.html

We may need to address that as part of this story, but maybe not, so long as we can succesfully nudge people close enough to the right spot.

[svevang]

As I understand: It should be the length of the shortest path across the WGS84 spheroid, assuming that we are using geography columns and a wgs84 projection.

Each projection has its own black box distance calculation, for example see proj4 for an implementation of these various black boxes

On Jun 5, 2015, at 1:52 AM, Michael Kirk notifications@github.com wrote:

Given I've just guess And I was wrong Then I should see a hint telling me how far away I am.

"Nope. You're 2.3 miles away." "Close! You're a 100 yards away."

This is also a convenient time to mention that I'm not sure how the "distance" metric in RGEO/postgis is being computed. I have verified that it is not a multiple of the haversine distance computed here: http://www.movable-type.co.uk/scripts/latlong.html

That may have to be addressed here, or maybe not, so long as we can get people close enough to nudge them towards the right spot.

— Reply to this email directly or view it on GitHub.

[michaelkirk]

Thanks for the tip Sam. Your knowledge here is really helpful. I'll see what I can figure out.

[michaelkirk]

I chose to surface the distance vaguely, rather than specifically, e.g

    if self.distance == nil {
      return "I can't tell how far away you are."
    } else if self.distance < 0.002 {
      return "Shoot! You're super close."
    } else if self.distance < 0.005 {
      return "You're close though."
    } else if self.distance < 0.015 {
      return "You are like a mile away."
    } else if self.distance < 0.1 {
      return "You're in the wrong neighborhood."
    } else {
      return "I'm not even sure you're on the right contintent."
    }

So I've sidestepped the issue of it not being completely accurate for now. I don't think it's actually very relevant to game play right now to solve that issue.