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+// Protocol Version 1
+
+package llmr.vector;
+
+option optimize_for = LITE_RUNTIME;
+
+enum geom_type {
+ Unknown = 0;
+ Point = 1;
+ LineString = 2;
+ Polygon = 3;
+}
+
+// Variant type encoding
+message value {
+ // Exactly one of these values may be present in a valid message
+ optional string string_value = 1;
+ optional float float_value = 2;
+ optional double double_value = 3;
+ optional int64 int_value = 4;
+ optional uint64 uint_value = 5;
+ optional sint64 sint_value = 6;
+ optional bool bool_value = 7;
+
+ extensions 8 to max;
+}
+
+message feature {
+ optional uint64 id = 1;
+
+ // Tags of this feature. Even numbered values refer to the nth
+ // value in the keys list on the tile message, odd numbered
+ // values refer to the nth value in the values list on the tile
+ // message.
+ repeated uint32 tags = 2 [ packed = true ];
+
+ // The type of geometry stored in this feature.
+ optional geom_type type = 3 [ default = Unknown ];
+
+ // Contains a stream of commands and parameters (vertices). The
+ // repeat count is shifted to the left by 3 bits. This means
+ // that the command has 3 bits (0-15). The repeat count
+ // indicates how often this command is to be repeated. Defined
+ // commands are:
+ // - MoveTo: 1 (2 parameters follow)
+ // - LineTo: 2 (2 parameters follow)
+ // - ClosePath: 15 (no parameters follow)
+ //
+ // Ex.: MoveTo(3, 6), LineTo(8, 12), LineTo(20, 34), ClosePath
+ // Encoded as: [ 3 6 18 5 6 12 22 15 ]
+ // == command type 15 (ClosePath)
+ // ===== relative LineTo(+12, +22) == LineTo(20, 34)
+ // === relative LineTo(+5, +6) == LineTo(8, 12)
+ // == [00010 010] = command type 2 (LineTo), length 2
+ // === relative MoveTo(+3, +6)
+ // = implicit command type 1 (MoveTo), length 1
+ // Commands are encoded as uint32 varints, vertex parameters are
+ // encoded as sint32 varints (zigzag). Vertex parameters are
+ // also encoded as deltas to the previous position. The original
+ // position is (0,0)
+ repeated uint32 geometry = 4 [ packed = true ];
+
+ // A list of indices to the geometry array that specify a triangulation of
+ // this geometry. This must only exist if this feature is a polygon.
+ // These are the valid indices for the example above:
+ // 0 ==> (3/6)
+ // 1 ==> (8/12)
+ // 2 ==> (20/34)
+ // Indices beyond 2 are invalid, as the total number of vertices is 3.
+ repeated sint32 triangulation = 5 [ packed = true ];
+
+ // The total number of vertices encoded in the geometry field. This is can
+ // be deduced by manually iterating through the geometry field, but we can
+ // just as well store the number to avoid the overhead on parsing.
+ optional uint32 vertex_count = 6;
+}
+
+// Stores a glyph with metrics and optional SDF bitmap information.
+message glyph {
+ required uint32 id = 1;
+
+ // A signed distance field of the glyph with a border of 3 pixels.
+ optional bytes bitmap = 2;
+
+ // Glyph metrics.
+ required uint32 width = 3;
+ required uint32 height = 4;
+ required sint32 left = 5;
+ required sint32 top = 6;
+ required uint32 advance = 7;
+}
+
+// Stores font face information and a list of glyphs.
+message face {
+ required string family = 1;
+ required string style = 2;
+ repeated glyph glyphs = 5;
+}
+
+// Stores the shaping information for the label with a given text
+message label {
+ // The original value ID this shaping information is for.
+ required uint32 text = 1;
+
+ // References the index of the font stack in the layer's fontstack array.
+ required uint32 stack = 2;
+
+ // Parallel arrays of face ID, glyph ID and position.
+ repeated uint32 faces = 3 [packed = true];
+ repeated uint32 glyphs = 4 [packed = true];
+ repeated uint32 x = 5 [packed = true];
+ repeated uint32 y = 6 [packed = true];
+}
+
+message layer {
+ // Any compliant implementation must first read the version
+ // number encoded in this message and choose the correct
+ // implementation for this version number before proceeding to
+ // decode other parts of this message.
+ required uint32 version = 15 [ default = 1 ];
+
+ required string name = 1;
+
+ // The actual features in this tile.
+ repeated feature features = 2;
+
+ // Dictionary encoding for keys
+ repeated string keys = 3;
+
+ // Dictionary encoding for values
+ repeated value values = 4;
+
+ // The bounding box in this tile spans from 0..4095 units
+ optional uint32 extent = 5 [ default = 4096 ];
+
+ // Total vertex count in this layer.
+ optional uint32 vertex_count = 6;
+
+ // Shaping information for labels contained in this tile.
+ repeated string faces = 7;
+ repeated label labels = 8;
+ repeated string stacks = 9;
+
+ extensions 16 to max;
+}
+
+message tile {
+ repeated layer layers = 3;
+
+ repeated face faces = 4;
+
+ extensions 16 to 8191;
+}