// Protocol Version 1
package mapnik.vector;
option optimize_for = LITE_RUNTIME;
message tile {
enum GeomType {
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 GeomType 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 (0-7). 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: 7 (no parameters follow)
//
// Commands are encoded as uint32 varints. Vertex parameters
// are encoded as deltas to the previous position and, as they
// may be negative, are further "zigzag" encoded as unsigned
// 32-bit ints:
//
// n = (n << 1) ^ (n >> 31)
//
// Ex.: MoveTo(3, 6), LineTo(8, 12), LineTo(20, 34), ClosePath
// Encoded as: [ 9 6 12 18 10 12 24 44 15 ]
// | | `> [00001 111] command type 7 (ClosePath), length 1
// | | ===== 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)
// `> [00001 001] = command type 1 (MoveTo), length 1
//
// The original position is (0,0).
repeated uint32 geometry = 4 [ 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 ];
extensions 16 to max;
}
repeated layer layers = 3;
extensions 16 to 8191;
}