MVT

This package contains functions and types for encoding a geometry in Mapbox Vector Tiles. This package depends on the protbuf package.

In short, a Tiles has Layers, which have Feautures. The Feature type is what holds a single geom.Geometry and associated metadata.

To encode a geometry into a tile, you need:

• a geometry
• a tile's geom.Extent in the same projection as the geometry
• the size of the tile you want to output in pixels

note: the geometry must not go outside the tile extent. If this is unknown, use the clip package before encoding.

To encode:

1. Call PrepareGeomtry, it returns a geom.Geometry that is "reprojected" into pixel values relative to the tile
2. Add the returned geometry to a Feature, optionally with an ID and tags by calling NewFeatures.
3. Add the feature to a Layer with a name for the layer by calling (*Layer).AddFeatures
4. Add the layer to a Tile by calling (*Tile).AddLayers
5. Get the protobuf tile by calling (*Tile).VTile
6. Encode the protobuf into bytes with proto.Marshal

For an example, check the use of this package in tegola/atlas/map.go