From 05de7283b43beb90679077e12346c08d0c5c2588 Mon Sep 17 00:00:00 2001
From: umpc <umpc@users.noreply.github.com>
Date: Thu, 13 Oct 2016 06:17:45 -0400
Subject: [PATCH] Non-essential changes

I changed style slightly to better fit in with the rest of the project's code, added some missing comments where needed, and added in the commented code that the unchanged bounds must be copied to both of the new bboxes if it is later refactored to work that way.
---
 geojson/bbox.go | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/geojson/bbox.go b/geojson/bbox.go
index 7c8b4c94..da469083 100644
--- a/geojson/bbox.go
+++ b/geojson/bbox.go
@@ -187,49 +187,47 @@ func BBoxesFromCenter(lat, lon, meters float64) (outer BBox) {
 	return outer
 }
 
-func BBoxBounds(lat, lon, meters float64) (float64, float64, float64, float64) {
+func BBoxBounds(lat, lon, meters float64) (latMin, lonMin, latMax, lonMax float64) {
 
 	// see http://janmatuschek.de/LatitudeLongitudeBoundingCoordinates#Latitude
+	lat = toRadians(lat)
+	lon = toRadians(lon)
+
 	r := meters / earthRadius // angular radius
 
-	φ1 := toRadians(lat)
-	λ1 := toRadians(lon)
+	latMin = lat - r
+	latMax = lat + r
 
-	latMin := φ1 - r
-	latMax := φ1 + r
+	latT := math.Asin(math.Sin(lat) / math.Cos(r))
+	lonΔ := math.Acos(( math.Cos(r) - math.Sin(latT) * math.Sin(lat)) / (math.Cos(latT) * math.Cos(lat) ))
 
-	latT   := math.Asin(math.Sin(φ1) / math.Cos(r))
-	lonΔ   := math.Acos(( math.Cos(r) - math.Sin(latT) * math.Sin(φ1)) / (math.Cos(latT) * math.Cos(φ1) ))
-
-	lonMin := λ1 - lonΔ
-	lonMax := λ1 + lonΔ
+	lonMin = lon - lonΔ
+	lonMax = lon + lonΔ
 
 	// Adjust for north poll
 	if latMax > math.Pi/2 {
-
 		lonMin = -math.Pi
-
 		latMax = math.Pi/2
 		lonMax = math.Pi
 	}
 
 	// Adjust for south poll
 	if latMin < -math.Pi/2 {
-
 		latMin = -math.Pi/2
 		lonMin = -math.Pi
-
 		lonMax = math.Pi
 	}
 
+	// Adjust for wraparound. Remove this if the commented-out condition below this block is added.
 	if lonMin < -math.Pi || lonMax > math.Pi {
 		lonMin = -math.Pi
 		lonMax = math.Pi
 	}
 
 /*
-	// Consider splitting into two bboxes and using the below checks and erasing above block for performance. See http://janmatuschek.de/LatitudeLongitudeBoundingCoordinates#PolesAnd180thMeridian
+	// Consider splitting area into two bboxes, using the below checks, and erasing above block for performance. See http://janmatuschek.de/LatitudeLongitudeBoundingCoordinates#PolesAnd180thMeridian
 
+	// Adjust for wraparound if minimum longitude is less than -180 degrees.
 	if lonMin < -math.Pi {
 // box 1:
 		latMin = latMin
@@ -243,10 +241,16 @@ func BBoxBounds(lat, lon, meters float64) (float64, float64, float64, float64) {
 		lonMax = lonMax
 	}
 
+	// Adjust for wraparound if minimum longitude is greater than -180 degrees.
 	if lonMax > math.Pi {
 // box 1:
+		latMin = latMin
+		latMax = latMax
+		lonMin = lonMin
 		lonMax = -math.Pi
 // box 2:
+		latMin = latMin
+		latMax = latMax
 		lonMin = -math.Pi
 		lonMax -= 2*math.Pi
 	}