Add support for non-Web-Mercator coordinate systems. "Real" mercator (CrunchyData#60)

end up being very easy: just supply the alternate EPSG numbers (3395)
as the planar bounds are the same as for web mercator. For other alternate
systems you will need to also include the bounds of the inital level-zero
tile.

Author: pramsey

README.md

@@ -65,16 +65,37 @@ In general the defaults are fine, and the program autodetects things like the se
 ```toml
 # Database connection
 DbConnection = "user=you host=localhost dbname=yourdb"
+
 # Close pooled connections after this interval
 DbPoolMaxConnLifeTime = "1h"
+
 # Hold no more than this number of connections in the database pool
 DbPoolMaxConns = 4
+
 # Look to read html templates from this directory
 AssetsPath = "/usr/share/pg_tileserv/assets"
+
 # Accept connections on this subnet (default accepts on all)
 HttpHost = "0.0.0.0"
+
 # Accept connections on this port
 HttpPort = 7800
+HttpsPort = 7801
+
+# HTTPS configuration
+# TLS server certificate full chain and private key
+# If you do not specify both, the TLS server will not be started
+TlsServerCertificateFile = "server.crt"
+TlsServerPrivateKeyFile = "server.key"
+```
+
+For SSL support, you will need both a server private key and an authority certificate. For testing purposes you can generate a self-signed key/cert pair using `openssl`:
+
+```bash
+openssl req  -nodes -new -x509  -keyout server.key -out server.crt
+```
+
+```toml
 # Advertise URLs relative to this server name
 # default is to looke this up from incoming request headers
 # UrlBase = "http://yourserver.com/"
@@ -88,11 +109,22 @@ MaxFeaturesPerTile = 10000
 DefaultMinZoom = 0
 # Advertise this maximum zoom level
 DefaultMaxZoom = 22
+
 # Allow any page to consume these tiles
 CORSOrigins = ["*"]
+
 # Output extra logging information?
 Debug = false
+
+# Default CS is Web Mercator (EPSG:3857)
+[CoordinateSystem]
+SRID = 3857
+Xmin = -20037508.3427892
+Ymin = -20037508.3427892
+Xmax = 20037508.3427892
+Ymax = 20037508.3427892
 ```
+You can use the **CoordinateSystem** block to output files in a system other than the default [Web Mercator](http://epsg.io/3857) projection. In order to view a map with multiple layers in a non-standard projection, you will have to ensure that all layers share the same projection, otherwise the layers will not line up.
 
 # Operation
 

bounds.go

@@ -7,74 +7,78 @@ import (
 
 // Bounds represents a box in Web Mercator space
 type Bounds struct {
+	SRID int     `json:"srid"`
 	Xmin float64 `json:"xmin"`
 	Ymin float64 `json:"ymin"`
 	Xmax float64 `json:"xmax"`
 	Ymax float64 `json:"ymax"`
 }
 
 func (b *Bounds) String() string {
-	return fmt.Sprintf("{Xmin:%g, Ymin:%g, Xmax:%g, Ymax:%g}",
-		b.Xmin, b.Ymin, b.Xmax, b.Ymax)
+	return fmt.Sprintf("{Xmin:%g, Ymin:%g, Xmax:%g, Ymax:%g, SRID:%d}",
+		b.Xmin, b.Ymin, b.Xmax, b.Ymax, b.SRID)
 }
 
 // SQL returns the SQL fragment to create this bounds in the database
 func (b *Bounds) SQL() string {
-	return fmt.Sprintf("ST_MakeEnvelope(%g, %g, %g, %g, 3857)",
+	return fmt.Sprintf("ST_MakeEnvelope(%g, %g, %g, %g, %d)",
 		b.Xmin, b.Ymin,
-		b.Xmax, b.Ymax)
+		b.Xmax, b.Ymax, b.SRID)
 }
 
 // Expand increases the size of this bounds in all directions, respecting
 // the limits of the Web Mercator plane
 func (b *Bounds) Expand(size float64) {
-	worldMin := -0.5 * worldMercWidth
-	worldMax := 0.5 * worldMercWidth
-	b.Xmin = math.Max(b.Xmin-size, worldMin)
-	b.Ymin = math.Max(b.Ymin-size, worldMin)
-	b.Xmax = math.Min(b.Xmax+size, worldMax)
-	b.Ymax = math.Min(b.Ymax+size, worldMax)
+	serverBounds, _ := getServerBounds()
+	b.Xmin = math.Max(b.Xmin-size, serverBounds.Xmin)
+	b.Ymin = math.Max(b.Ymin-size, serverBounds.Ymin)
+	b.Xmax = math.Min(b.Xmax+size, serverBounds.Xmax)
+	b.Ymax = math.Min(b.Ymax+size, serverBounds.Ymax)
 	return
 }
 
+// func fromMercator(x float64, y float64) (lng float64, lat float64) {
+// 	// worldMercWidth is the width of the Web Mercator plane
+// 	worldMercWidth := 40075016.6855784
+// 	mercSize := worldMercWidth / 2.0
+// 	lng = x * 180.0 / mercSize
+// 	lat = 180.0 / math.Pi * (2.0*math.Atan(math.Exp((y/mercSize)*math.Pi)) - math.Pi/2.0)
+// 	return lng, lat
+// }
+
 func (b *Bounds) sanitize() {
-	if b.Ymin < -90 {
-		b.Ymin = 90
-	}
-	if b.Ymax > 90 {
-		b.Ymax = 90
-	}
-	if b.Xmin < -180 {
-		b.Xmin = -180
-	}
-	if b.Xmax > 180 {
-		b.Xmax = 180
+	if b.SRID == 4326 {
+		if b.Ymin < -90 {
+			b.Ymin = 90
+		}
+		if b.Ymax > 90 {
+			b.Ymax = 90
+		}
+		if b.Xmin < -180 {
+			b.Xmin = -180
+		}
+		if b.Xmax > 180 {
+			b.Xmax = 180
+		}
 	}
 	return
 }
 
-func fromMercator(x float64, y float64) (lng float64, lat float64) {
-	mercSize := worldMercWidth / 2.0
-	lng = x * 180.0 / mercSize
-	lat = 180.0 / math.Pi * (2.0*math.Atan(math.Exp((y/mercSize)*math.Pi)) - math.Pi/2.0)
-	return lng, lat
-}
-
 // Json returns the bounds in array for form consumption
 // by Json formats that like it that way
-func (b *Bounds) Json() []float64 {
-	s := make([]float64, 4)
-	s[0], s[1] = fromMercator(b.Xmin, b.Ymin)
-	s[2], s[3] = fromMercator(b.Xmax, b.Ymax)
-	return s
-}
+// func (b *Bounds) Json() []float64 {
+// 	s := make([]float64, 4)
+// 	s[0], s[1] = fromMercator(b.Xmin, b.Ymin)
+// 	s[2], s[3] = fromMercator(b.Xmax, b.Ymax)
+// 	return s
+// }
 
 // Center returns the center of the bounds in array format
 // for consumption by Json formats that like it that way
-func (b *Bounds) Center() []float64 {
-	xc := (b.Xmin + b.Xmax) / 2.0
-	yc := (b.Ymin + b.Ymax) / 2.0
-	s := make([]float64, 2)
-	s[0], s[1] = fromMercator(xc, yc)
-	return s
-}
+// func (b *Bounds) Center() []float64 {
+// 	xc := (b.Xmin + b.Xmax) / 2.0
+// 	yc := (b.Ymin + b.Ymax) / 2.0
+// 	s := make([]float64, 2)
+// 	s[0], s[1] = fromMercator(xc, yc)
+// 	return s
+// }

config/pg_tileserv.toml.example

@@ -59,3 +59,20 @@
 
 # Output extra logging information?
 # Debug = false
+
+# Default CS is Web Mercator (EPSG:3857)
+# [CoordinateSystem]
+# SRID = 3857
+# Xmin = -20037508.3427892
+# Ymin = -20037508.3427892
+# Xmax = 20037508.3427892
+# Ymax = 20037508.3427892
+
+# "True" Mercator (EPSG:3395) is only a little different
+# [CoordinateSystem]
+# SRID = 3395
+# Xmin = -20037508.342789244
+# Ymin = -20037508.342789244
+# Xmax = 20037508.342789244
+# Ymax = 20037508.342789244
+

go.mod

@@ -3,14 +3,15 @@ module github.com/CrunchyData/pg_tileserv
 go 1.13
 
 require (
-	github.com/gorilla/handlers v1.4.2
-	github.com/gorilla/mux v1.7.3
-	github.com/jackc/pgconn v1.3.2
-	github.com/jackc/pgtype v1.0.2
-	github.com/jackc/pgx/v4 v4.1.2
-	github.com/pborman/getopt v0.0.0-20190409184431-ee0cd42419d3
-	github.com/sirupsen/logrus v1.4.2
-	github.com/spf13/viper v1.6.1
-	github.com/stretchr/testify v1.4.0
+	github.com/Masterminds/sprig/v3 v3.1.0
+	github.com/gorilla/handlers v1.5.1
+	github.com/gorilla/mux v1.8.0
+	github.com/jackc/pgconn v1.7.2
+	github.com/jackc/pgtype v1.6.1
+	github.com/jackc/pgx/v4 v4.9.2
+	github.com/pborman/getopt/v2 v2.1.0
+	github.com/sirupsen/logrus v1.7.0
+	github.com/spf13/viper v1.7.1
+	github.com/stretchr/testify v1.6.1
 	github.com/theckman/httpforwarded v0.4.0
 )