From 4bcef2cb112cfd9bab4c5fdb725cf1f0aa0e527c Mon Sep 17 00:00:00 2001
From: Eric Fischer <enf@pobox.com>
Date: Thu, 13 Sep 2018 17:04:22 -0700
Subject: [PATCH] Work on reading dimension descriptions

---
 mvt.cpp | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 mvt.hpp |  8 ++++++++
 2 files changed, 57 insertions(+)

diff --git a/mvt.cpp b/mvt.cpp
index 8aa6b2b..3d5d858 100644
--- a/mvt.cpp
+++ b/mvt.cpp
@@ -144,6 +144,7 @@ bool mvt_tile::decode(std::string &message, bool &was_compressed) {
 		{
 			protozero::pbf_reader layer_reader(reader.get_message());
 			mvt_layer layer;
+			std::vector<mvt_dimension> dimensions;
 
 			while (layer_reader.next()) {
 				switch (layer_reader.tag()) {
@@ -277,6 +278,54 @@ bool mvt_tile::decode(std::string &message, bool &was_compressed) {
 					break;
 				}
 
+				case 10: /* dimensions */
+				{
+					protozero::pbf_reader dimension_reader(layer_reader.get_message());
+					mvt_dimension dimension;
+
+					dimension.scale = 1;
+					dimension.global_offset = 0;
+					dimension.offset = 0;
+
+					while (dimension_reader.next()) {
+						switch (dimension_reader.tag()) {
+						case 2:
+							dimension.is_elevation = dimension_reader.get_bool();
+							break;
+
+						case 3:
+							dimension.offset = dimension_reader.get_sint64();
+							break;
+
+						case 4:
+							dimension.scale = dimension_reader.get_sint64();
+							break;
+
+						case 8:
+							dimension.scale = dimension_reader.get_double();
+							break;
+
+						case 5:
+							dimension.global_offset = dimension_reader.get_sint64();
+							break;
+
+						case 9:
+							dimension.global_offset = dimension_reader.get_double();
+							break;
+
+						case 10:
+							dimension.name = dimension_reader.get_string();
+							break;
+
+						default:
+							dimension_reader.skip();
+							break;
+						}
+					}
+
+					break;
+				}
+
 				case 15: /* version */
 					layer.version = layer_reader.get_uint32();
 					break;
diff --git a/mvt.hpp b/mvt.hpp
index 587f2cf..f7f877b 100644
--- a/mvt.hpp
+++ b/mvt.hpp
@@ -112,6 +112,14 @@ struct mvt_value {
 	}
 };
 
+struct mvt_dimension {
+	bool is_elevation;
+	long offset;
+	double scale;
+	double global_offset;
+	std::string name;
+};
+
 struct mvt_layer {
 	int version = 0;
 	std::string name = "";