bext - External Dependencies for BRL-CAD

bext builds third-party libraries and helper tools used by BRL-CAD. By default it prefers suitable system packages and builds local copies only when they are needed.

Quick start

Clone the repository, configure with the official auto preset, and build:

git clone https://github.com/BRL-CAD/bext
cd bext
cmake --preset auto
cmake --build build/auto --config Release --parallel 8

Submodules are populated on demand during configure. For checkout and platform setup details, see INSTALL.md.

The preset workflow relies on CMake's newer preset support. If you are using CMake 3.19 or 3.20, use the raw configure equivalents below.

Optional bootstrap

If you want to fetch a given profile's source submodules up front instead of letting configure fetch them on demand:

cmake -DPROFILE=auto -P CMake/BextBootstrap.cmake
cmake --preset auto

Use LIST_ONLY=ON to preview the selected submodules without fetching them, and GIT_SHALLOW_CLONE=ON to specify shallow clones during bootstrap.

How manual selection works

Build selection happens in three layers:

1. USE_* options decide which dependency families are in scope.
2. For in-scope packages, the default behavior is to use a suitable system package if one is found and build a local copy only when needed.
3. ENABLE_<pkg>=ON or OFF overrides one package explicitly.

Default USE_* values:

• USE_BRLCAD=ON
• USE_BRLCAD_EXTRA=ON
• USE_GDAL=ON
• USE_QT=ON
• USE_TCL=ON
• USE_APPLESEED=OFF
• USE_OSPRAY=OFF

ENABLE_ALL=ON changes step 2 by preferring local builds for packages in the active USE_* groups. It does not turn on groups whose USE_* option is OFF.

When bext is driven from a BRL-CAD build, BRLCAD_COMPONENTS can further narrow some BRL-CAD-related packages to only those needed by the requested component set.

Official profiles

The supported configure entry points are:

• auto - standard BRL-CAD-oriented profile using suitable system packages when found
• bundled - standard BRL-CAD-oriented profile with bundled/local builds preferred for all active groups
• minimal - core BRL-CAD profile without extras, GDAL, Qt, Tcl/Tk, Appleseed, or OSPRay
• everything - all current groups enabled with bundled/local builds preferred throughout

Use them like this:

cmake --preset auto
cmake --preset bundled
cmake --preset minimal
cmake --preset everything

Build using the preset's build directory:

cmake --build build/auto --config Release --parallel 8

Raw configure equivalents

auto:

cmake ../bext -DCMAKE_BUILD_TYPE=Release

bundled:

cmake ../bext -DENABLE_ALL=ON -DCMAKE_BUILD_TYPE=Release

minimal:

cmake ../bext \
  -DUSE_BRLCAD_EXTRA=OFF \
  -DUSE_GDAL=OFF \
  -DUSE_QT=OFF \
  -DUSE_TCL=OFF \
  -DCMAKE_BUILD_TYPE=Release

everything:

cmake ../bext \
  -DENABLE_ALL=ON \
  -DUSE_APPLESEED=ON \
  -DUSE_OSPRAY=ON \
  -DCMAKE_BUILD_TYPE=Release

Build outputs

By default, CMAKE_INSTALL_PREFIX is the build directory. bext creates two output trees under that prefix:

• install/ - files intended to be bundled with downstream software
• noinstall/ - build-only tools and compile-time-only assets

When BRL-CAD consumes a bext build, BRLCAD_EXT_DIR should point at the parent directory containing both install/ and noinstall/.

Using the build outputs with BRL-CAD

If you used the auto preset, BRLCAD_EXT_DIR should be ../bext/build/auto. Configure BRL-CAD with:

git clone https://github.com/BRL-CAD/brlcad
mkdir brlcad_build
cd brlcad_build
cmake ../brlcad -DBRLCAD_EXT_DIR=../bext_build -DCMAKE_BUILD_TYPE=Release
cmake --build . --config Release --parallel 8

If you built Qt in bext, also enable Qt in BRL-CAD:

cmake ../brlcad \
  -DBRLCAD_EXT_DIR=../bext_build \
  -DBRLCAD_ENABLE_QT=ON \
  -DCMAKE_BUILD_TYPE=Release

More information

• INSTALL.md - platform prerequisites, checkout options, and setup caveats
• DEPENDENCIES.md - package-to-group reference, output classification, and dependency addition workflow
• NOTES.md - maintainer notes and submodule procedures