README.md

Linux

This guide explains how to get started building and running MapLibre Native on Linux. The guide focusses on a Ubuntu 22.04. The build process should give you a set of .a files that you can use to include MapLibre Native in other C++ projects, as well as a set of executables that you can run to render map tile images and test the project.

Requirements

The following system libraries need to be installed.

apt install libcurl4-openssl-dev libglfw3-dev libuv1-dev libpng-dev libicu-dev libjpeg-turbo8-dev libwebp-dev xvfb

Optional: libsqlite3-dev (also available as vendored dependency).

The following tools need to be available.

apt install clang git cmake ccache ninja-build pkg-config

Docker

You can use a Docker container to build MapLibre Native. A Dockerfile that installes the required dependencies when the image is built is provided in this directory.

Build image with:

# in platform/linux
docker build -t maplibre-native-image .

Run image with:

# in repo root directory
docker run --rm -it -v "$(pwd)":/root/ maplibre-native-image

Build

First, clone the repository. This repository uses git submodules, that are required to build the project.

git clone --recurse-submodules -j8 https://github.com/maplibre/maplibre-native.git
cd maplibre-native

To create the build, run the following commands from the root of the project:

cmake -B build -GNinja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=RelWithDebInfo -DMLN_WITH_CLANG_TIDY=OFF -DMLN_WITH_COVERAGE=OFF -DMLN_DRAWABLE_RENDERER=ON -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON

cmake --build build --target mbgl-render -j $(nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null)

mbgl-render

If all went well, there should now be a ./build/bin/mbgl-render binary that you can run to generate map tile images. To test that it is working properly, run the following command.

./build/bin/mbgl-render --style https://raw.githubusercontent.com/maplibre/demotiles/gh-pages/style.json --output out.png

I get an error Error: Failed to open X display. when I run this command.

If you're setting up MapLibre Native on a headless server (i.e. one without a display), you'll need to simulate an X server to do any rendering. Install xvfb and xauth and run the following command:

xvfb-run -a ./build/bin/mbgl-render --style https://raw.githubusercontent.com/maplibre/demotiles/gh-pages/style.json --output out.png

This should produce an out.png map tile image with the default MapLibre styling from the MapLibre demo.

Using your own style/tiles

You can also use the mbgl-render command to render images from your own style or tile set. To do so, you will need a data source and a style JSON file.

For the purposes of this exercise, you can use the zurich_switzerland.mbtiles from here, and this following style.json file. Download both by running the commands below.

wget https://github.com/acalcutt/tileserver-gl/releases/download/test_data/zurich_switzerland.mbtiles
wget https://gist.githubusercontent.com/louwers/d7607270cbd6e3faa05222a09bcb8f7d/raw/4e9532e1760717865df8aeff08f9bcf100f9e8c4/style.json

Note that this style is totally inadequate for any real use beyond testing your custom setup. Replace the source URL mbtiles:///path/to/zurich_switzerland.mbtiles with the actual path to your .mbtiles file. You can use this command if you downloaded both files to the working directory:

sed -i "s#/path/to#$PWD#" style.json 

Next, run the following command.

./build/bin/mbgl-render --style style.json --output out.png

This should produce an out.png image in your current directory with a barebones image of the world.

Running the render tests

To check that the output of the rendering is correct, we compare actual rendered PNGs for simple styles with expected PNGs. The content of the tests used to be stored in the MapLibre GL JS repository, which means that GL JS and Native are mostly pixel-identical in their rendering.

The directory structure of the render tests looks like:

metrics/
  integration/
    render-tests/
      <name-of-style-spec-feature>/
        <name-of-feature-value>/
          expected.png
          style.json

After the render test run, the folder will also contain an actual.png file and a diff.png which is the difference between the expected and the actual image. There is a pixel difference threshold value which is used to decide if a render test passed or failed.

Run all render tests with:

./build/mbgl-render-test-runner --manifestPath metrics/linux-clang8-release-style.json

Or a single test with:

./build/mbgl-render-test-runner --manifestPath metrics/linux-clang8-release-style.json --filter "render-tests/fill-visibility/visible"

The render test results are summarized in a HTML website located next to the manifest file. For example, running metrics/linux-clang8-release-style.json produces a summary at metrics/linux-clang8-release-style.html.