GeometryLib

GeometryLib is a C++20 3D geometry library built with CMake. It provides analytic geometry primitives — points, vectors, lines, rays, and planes — a bounded shapes layer — segments, triangles, circles, and axis-aligned bounding boxes — and a spatial query layer covering intersection, parallelism, projection, and distance operations. The API is clean, well-tested, and uses scale-independent floating-point comparisons throughout.

The project exports an installable library target (GeometryLib::Geometry), ships CMake package configuration files for downstream find_package consumers, and uses GoogleTest for unit testing.

Project layout

Geometry/
├── CMakeLists.txt
├── CMakePresets.json
├── cmake/
│   ├── GeometryLibConfig.cmake.in
│   ├── GeometrySources.cmake        # lists all library source files
│   └── GeometryTestSources.cmake   # lists all test source files
├── include/Geometry/
│   ├── Primitives/   # point, vector, line, ray, plane
│   ├── Shapes/       # segment, triangle, circle, bounding_box
│   └── Queries/      # intersect, parallel, project, distance
├── src/              # mirrors include/ layout; also contains utils/
└── tests/            # mirrors include/ layout

API documentation

The documentation is published automatically at: https://psiridis.github.io/GeometryLib/

It is regenerated on every push to main via the GitHub Actions workflow in .github/workflows/docs.yml.

To build the docs locally:

doxygen Doxyfile
open docs/html/index.html

Requirements

• CMake 3.20 or newer
• A C++20-capable compiler
• Ninja
• Git when configuring a build with tests enabled, because GoogleTest is fetched at configure time
• Doxygen (optional — only required to build the documentation locally)

Notes:

• The provided presets use the Ninja generator explicitly.
• ctest is bundled with CMake and is used to run the test suite.

Configure and build

The recommended workflow is to use the presets defined in CMakePresets.json.

Debug build

The debug preset configures the project in build-debug, enables tests, and sets the install prefix to install/ in the source tree.

cmake --preset debug
cmake --build --preset debug

Release build

The release preset configures the project in build-release and disables tests.

cmake --preset release
cmake --build --preset release

AddressSanitizer build

The asan preset configures the project in build-asan, enables tests, and adds AddressSanitizer flags.

cmake --preset asan
cmake --build --preset asan

Reconfigure after CMake changes

If you change CMakeLists.txt, presets, or files included from CMake, rerun the configure step before building:

cmake --preset debug
cmake --build --preset debug

Install the library

The install rules export the library target, public headers, and package configuration files.

Install with a build preset

cmake --preset debug
cmake --build --preset install-debug

For release:

cmake --preset release
cmake --build --preset install-release

Install from an existing build directory

cmake --install build-debug

By default, the presets install into:

<project-root>/install

Installed package files are placed under:

install/
├── include/
└── lib/cmake/GeometryLib/

Run tests

Tests are enabled in the debug and asan presets and are built into a single executable named geometry_tests.

Run tests with CTest

cmake --preset debug
cmake --build --preset debug --target geometry_tests
ctest --preset debug

The debug test preset already enables output on failure.

Run the test executable directly

./build-debug/geometry_tests

If CTest reports geometry_tests_NOT_BUILT, reconfigure and rebuild the target:

cmake --preset debug
cmake --build --preset debug --target geometry_tests
ctest --preset debug

Use the library from another CMake project

After installation, consumers can use the exported package configuration.

find_package(GeometryLib CONFIG REQUIRED)

add_executable(myapp main.cpp)
target_link_libraries(myapp PRIVATE GeometryLib::Geometry)

If GeometryLib is installed in a non-standard location, point CMake at the install prefix:

cmake -S . -B build -DCMAKE_PREFIX_PATH=/path/to/Geometry/install

Development notes

• Library implementation files are listed in cmake/GeometrySources.cmake.
• Test source files are listed in cmake/GeometryTestSources.cmake.
• GoogleTest is fetched only when BUILD_TESTING is enabled.
• The exported target name for consumers is GeometryLib::Geometry.
• GEOM_ASSERT(condition) fires before every throw in debug builds, providing an early abort with file and line info. Both mechanisms remain active — the assert for development, the throw for release-time error handling by callers.
• Floating-point comparisons use almost_equal(a, b) from src/utils/numerical_utils.hpp. Shared tolerance constants k_abs_eps (1e-12) and k_rel_eps (1e-9) are defined there and used consistently across all modules. All threshold checks in the query layer are scale-independent (squared ratios, no raw absolute distances). safe_acos(x) clamps its argument to [-1, 1] before calling std::acos to prevent NaN from floating-point rounding.