From d4504da2f5b1f0b4782b9d158b382e5bab3c8331 Mon Sep 17 00:00:00 2001
From: Eric Fischer <enf@pobox.com>
Date: Wed, 27 Apr 2016 11:36:56 -0700
Subject: [PATCH] Rationalize the highest allowed maxzoom in terms of detail

---
 geojson.c                    | 27 ++++++++-----
 tests/highzoom/out/-z30.json | 78 ++----------------------------------
 2 files changed, 20 insertions(+), 85 deletions(-)

diff --git a/geojson.c b/geojson.c
index e5c7afa..009ac9a 100644
--- a/geojson.c
+++ b/geojson.c
@@ -750,7 +750,8 @@ int serialize_geometry(json_object *geometry, json_object *properties, const cha
 	 */
 	int feature_minzoom = 0;
 	if (mb_geometry[t] == VT_LINE) {
-		for (feature_minzoom = 0; feature_minzoom < 31; feature_minzoom++) {
+		// Skip z0 check because everything is always in the one z0 tile
+		for (feature_minzoom = 1; feature_minzoom < 31; feature_minzoom++) {
 			unsigned mask = 1 << (32 - (feature_minzoom + 1));
 
 			if (((bbox[0] & mask) != (bbox[2] & mask)) || ((bbox[1] & mask) != (bbox[3] & mask))) {
@@ -2774,6 +2775,21 @@ int main(int argc, char **argv) {
 	files_open_at_start = open("/dev/null", O_RDONLY);
 	close(files_open_at_start);
 
+	if (full_detail <= 0) {
+		full_detail = 12;
+	}
+
+	if (full_detail < min_detail || low_detail < min_detail) {
+		fprintf(stderr, "%s: Full detail and low detail must be at least minimum detail\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	// Need two checks: one for geometry representation, the other for
+	// index traversal when guessing base zoom and drop rate
+	if (maxzoom > 32 - full_detail) {
+		maxzoom = 32 - full_detail;
+		fprintf(stderr, "Highest supported zoom with detail %d is %d\n", full_detail, maxzoom);
+	}
 	if (maxzoom > MAX_ZOOM) {
 		maxzoom = MAX_ZOOM;
 		fprintf(stderr, "Highest supported zoom is %d\n", maxzoom);
@@ -2788,15 +2804,6 @@ int main(int argc, char **argv) {
 		basezoom = maxzoom;
 	}
 
-	if (full_detail <= 0) {
-		full_detail = 12;
-	}
-
-	if (full_detail < min_detail || low_detail < min_detail) {
-		fprintf(stderr, "%s: Full detail and low detail must be at least minimum detail\n", argv[0]);
-		exit(EXIT_FAILURE);
-	}
-
 	geometry_scale = 32 - (full_detail + maxzoom);
 	if (geometry_scale < 0) {
 		geometry_scale = 0;
diff --git a/tests/highzoom/out/-z30.json b/tests/highzoom/out/-z30.json
index 3c714e3..1790e81 100644
--- a/tests/highzoom/out/-z30.json
+++ b/tests/highzoom/out/-z30.json
@@ -1,10 +1,10 @@
 { "type": "FeatureCollection", "properties": {
 "bounds": "-122.000000,37.000000,0.000000,51.500000",
-"center": "-122.000000,37.000008,24",
+"center": "-121.999912,37.000000,20",
 "description": "tests/highzoom/out/-z30.json.check.mbtiles",
 "format": "pbf",
-"json": "{\"vector_layers\": [ { \"id\": \"in\", \"description\": \"\", \"minzoom\": 0, \"maxzoom\": 24, \"fields\": {\"name\": \"String\"} } ] }",
-"maxzoom": "24",
+"json": "{\"vector_layers\": [ { \"id\": \"in\", \"description\": \"\", \"minzoom\": 0, \"maxzoom\": 20, \"fields\": {\"name\": \"String\"} } ] }",
+"maxzoom": "20",
 "minzoom": "0",
 "name": "tests/highzoom/out/-z30.json.check.mbtiles",
 "type": "overlay",
@@ -369,76 +369,4 @@
 { "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ 0.000000, 51.500000 ] } }
 ] }
 ] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 21, "x": 337874, "y": 816274 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "Santa Cruz" }, "geometry": { "type": "Point", "coordinates": [ -122.000084, 37.000085 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 21, "x": 1048575, "y": 697425 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ -0.000172, 51.500087 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 21, "x": 1048576, "y": 697425 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ 0.000000, 51.500087 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 22, "x": 675748, "y": 1632549 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "Santa Cruz" }, "geometry": { "type": "Point", "coordinates": [ -122.000084, 37.000016 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 22, "x": 2097151, "y": 1394851 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ -0.000086, 51.500034 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 22, "x": 2097152, "y": 1394851 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ 0.000000, 51.500034 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 23, "x": 1351497, "y": 3265098 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "Santa Cruz" }, "geometry": { "type": "Point", "coordinates": [ -122.000041, 37.000016 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 23, "x": 4194303, "y": 2789703 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ -0.000043, 51.500007 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 23, "x": 4194304, "y": 2789703 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ 0.000000, 51.500007 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 24, "x": 2702995, "y": 6530196 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "Santa Cruz" }, "geometry": { "type": "Point", "coordinates": [ -122.000020, 37.000016 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 24, "x": 8388607, "y": 5579406 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ -0.000021, 51.500007 ] } }
-] }
-] }
-,
-{ "type": "FeatureCollection", "properties": { "zoom": 24, "x": 8388608, "y": 5579406 }, "features": [
-{ "type": "FeatureCollection", "properties": { "layer": "in" }, "features": [
-{ "type": "Feature", "properties": { "name": "London" }, "geometry": { "type": "Point", "coordinates": [ 0.000000, 51.500007 ] } }
-] }
-] }
 ] }