[core] add support for mapzen terrarium (#11154)

* add support for mapzen terrarium

* Encoding --> DEMEncoding, avoid if statement when unpacking elevation values

* add Terrarium test

* update submodule

* remove redundant checks

1 files changed, 10 insertions, 0 deletions

diff --git a/src/mbgl/style/conversion/tileset.cpp b/src/mbgl/style/conversion/tileset.cpp
index 88e78b1a83..6d89cef944 100644
--- a/src/mbgl/style/conversion/tileset.cpp
+++ b/src/mbgl/style/conversion/tileset.cpp
@@ -40,6 +40,16 @@ optional<Tileset> Converter<Tileset>::operator()(const Convertible& value, Error
         }
     }
 
+    auto encodingValue = objectMember(value, "encoding");
+    if (encodingValue) {
+        optional<std::string> encoding = toString(*encodingValue);
+        if (encoding && *encoding == "terrarium") {
+            result.encoding = Tileset::DEMEncoding::Terrarium;
+        } else if (encoding && *encoding != "mapbox") {
+            error = { "invalid raster-dem encoding type - valid types are 'mapbox' and 'terrarium' " };
+        }
+    }
+
     auto minzoomValue = objectMember(value, "minzoom");
     if (minzoomValue) {
         optional<float> minzoom = toNumber(*minzoomValue);