added ability to state the srid of the bounds for cache

README.md

@@ -27,7 +27,7 @@ Tegola is a vector tile server delivering [Mapbox Vector Tiles](https://github.c
 
 ```
 tegola is a vector tile server
-Version: v0.17.0
+Version: v0.21.0
 
 Usage:
   tegola [command]

cmd/tegola/cmd/cache/seed_purge.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"runtime"
 	"strings"
@@ -48,8 +49,8 @@ var (
 	cacheOverwrite bool
 	// cacheBounds is the bounds that the cache is within. defaults to -180, -85.0511, 180, 85.0511
 	cacheBounds string
-	// cacheBoundsWGS84 is the grid system that the bounds is at. If set then we should use WGS84, otherwise assume it's in Pseudo-Mercator
-	cacheBoundsWGS84 bool
+	// cacheBoundsSRID is the srid of grid system that the bounds is at. Should Default to 4326
+	cacheBoundsSRID int
 	// cacheMap is the name of the map
 	cacheMap string
 	// cacheLogThreshold is cache threshold while seeding, to log output for tiles that take longer than this (in milliseconds) to render
@@ -79,7 +80,7 @@ func init() {
 	SeedPurgeCmd.PersistentFlags().Int64VarP(&cacheLogThreshold, "log-threshold", "", 0, "during seeding, only log tiles that take this number of milliseconds or longer to render (default all tiles)")
 
 	SeedPurgeCmd.Flags().StringVarP(&cacheBounds, "bounds", "", "-180,-85.0511,180,85.0511", "lng/lat bounds to seed the cache with in the format: minx, miny, maxx, maxy")
-	SeedPurgeCmd.PersistentFlags().BoolVarP(&cacheBoundsWGS84, "wgs84", "", false, "the grid system for bounds. This flag indicates that the grid is WGS 84; otherwise it's assumed to be in Pseudo-Mercator")
+	SeedPurgeCmd.Flags().IntVarP(&cacheBoundsSRID, "bounds-srid", "", int(proj.EPSG4326), "the srid of the grid system for bounds.")
 
 	SeedPurgeCmd.PersistentPreRunE = seedPurgeCmdValidatePersistent
 	SeedPurgeCmd.PreRunE = seedPurgeCmdValidate
@@ -147,6 +148,15 @@ func seedPurgeCmdValidatePersistent(cmd *cobra.Command, args []string) error {
 }
 
 func seedPurgeCmdValidate(cmd *cobra.Command, args []string) (err error) {
+	// validate the cache-bounds-srid
+	if !proj.IsKnownConversionSRID(proj.EPSGCode(cacheBoundsSRID)) {
+		var str strings.Builder
+		str.WriteString(fmt.Sprintf("SRID=%d is not a know conversion  ePSG code\n known codes are:", cacheBoundsSRID))
+		for _, code := range proj.AvailableConversions() {
+			str.WriteString(fmt.Sprintf(" %d\n", int(code)))
+		}
+		return errors.New(str.String())
+	}
 
 	// validate and set bounds flag
 	boundsParts := strings.Split(strings.TrimSpace(cacheBounds), ",")
@@ -195,11 +205,7 @@ func seedPurgeCommand(_ *cobra.Command, _ []string) (err error) {
 		}
 	}()
 
-	srid := proj.EPSGCode(proj.EPSG3857)
-	if cacheBoundsWGS84 {
-		srid = proj.EPSG4326
-	}
-	grid := slippy.NewGrid(srid, 0)
+	grid := slippy.NewGrid(proj.EPSGCode(cacheBoundsSRID), 0)
 
 	log.Info("zoom list: ", zooms)
 	tileChannel := generateTilesForBounds(ctx, seedPurgeBounds, zooms, grid)
@@ -214,7 +220,7 @@ func generateTilesForBounds(ctx context.Context, bounds [4]float64, zooms []uint
 	}
 
 	if grid == nil {
-		grid = slippy.NewGrid(proj.EPSG3857, 0)
+		grid = slippy.NewGrid(proj.EPSGCode(cacheBoundsSRID), 0)
 	}
 
 	go func() {