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Building

The plugin is a small CMake project that links two things you build or vendor first: the tile57 static library (the chart engine) and the OpenCPN plugin API (vendored as a git submodule).

Requirements​

  • A C++17 compiler and CMake ≥ 3.16
  • wxWidgets with the core, base, and gl components (the same major version OpenCPN uses — 3.2.x)
  • OpenGL and GLEW
  • tile57 built as a static library (libtile57.a + include/tile57.h), which needs Zig 0.16 to build

The OpenCPN plugin API is vendored as the opencpn-libs submodule (its header-only api-18 target, matching the opencpn_plugin_118 base class), so no separate OpenCPN source checkout is needed.

1. Clone with submodules​

git clone --recursive https://github.com/beetlebugorg/tile57-opencpn-plugin.git
# …or, in an already-cloned checkout:
git submodule update --init

2. Build tile57 (the chart engine)​

The plugin links libtile57.a. In a tile57 checkout (clone it recursively — it has nested submodules for the IHO S-101 catalogues), run:

git clone --recursive https://github.com/beetlebugorg/tile57.git
cd tile57
zig build -Doptimize=ReleaseFast   # -> zig-out/lib/libtile57.a + include/tile57.h

By default the plugin looks for tile57 at ../tile57 (a sibling directory). Point elsewhere with -DTILE57_DIR=/path/to/tile57 when configuring CMake.

3. Configure and build the plugin​

cmake -S . -B build -DTILE57_DIR=/path/to/tile57
cmake --build build -j

The result is build/libtile57_pi.so (Linux) or build/libtile57_pi.dylib (macOS).

Linux​

The dependencies are all in the distro package manager, e.g. on Debian/Ubuntu:

sudo apt-get install -y \
  build-essential cmake \
  libwxgtk3.2-dev libwxgtk-gl3.2-dev \
  libglew-dev libgl1-mesa-dev

A plugin module on Linux is allowed to leave the OpenCPN base-class and PI_* helper symbols undefined; they resolve when OpenCPN dlopens the plugin.

macOS​

Point CMake at Homebrew so it finds GLEW and wxWidgets:

cmake -S . -B build \
  -DTILE57_DIR=/path/to/tile57 \
  -DCMAKE_PREFIX_PATH="$(brew --prefix)"
cmake --build build -j

A macOS plugin must use the same wxWidgets as OpenCPN.app, or a second wxWidgets loads and OpenCPN silently drops the plugin. The build compiles against your (Homebrew) wx, then a post-build step (cmake/fix-macos-libs.sh) repoints the plugin's wx references to the app's bundled copy and re-signs the binary ad-hoc (the install_name_tool retarget invalidates the code signature; an unsigned plugin is SIGKILLed at load). It looks for the app at OCPN_APP, default /Applications/OpenCPN.app:

cmake -S . -B build -DOCPN_APP=/path/to/OpenCPN.app ...

Continuous integration​

.github/workflows/ci.yml builds the plugin for Linux and Windows on every push. It builds tile57 with Zig first, then configures and builds the plugin, and uploads the resulting module as a workflow artifact.

Next​

Once you have a built module, see Getting Started to install it into OpenCPN and load a chart.