FLAME GPU 2 Template for CUDA C++

This repository can be used as a template for creating your own FLAME GPU 2 simulations or ensembles using the C++ (CUDA) interface.

FLAMEGPU/FLAMEGPU2 is downloaded via CMake and configured as a dependency of the project, as precompiled binary releases are not yet available.

The version of FLAME GPU fetched is pinned to a specific release of FLAME GPU, in case of API breaking changes. This is controlled using the FLAMEGPU_VERSION CMake variable, which can be modified in CMakeLists.txt, or as a configuration argument.

For details on how to develop a model using FLAME GPU 2, refer to the userguide & API documentation.

Python Interface

FLAME GPU 2 also provides a python-based interface for writing models. If you wish to use this instead of the CUDA C++ interface, see FLAMEGPU/FLAMEGPU2-model-template-python.

Requirements

Building FLAME GPU from source has the following requirements. There are also optional dependencies which are required for some components, such as Documentation or Python bindings, however these are not strictly required, and are not required for this standalone example.

Building FLAME GPU has the following requirements. There are also optional dependencies which are required for some components, such as Documentation or Python bindings.

• CMake >= 3.18
  • >= 3.20 if building python bindings using a multi-config generator (Visual Studio, Eclipse or Ninja Multi-Config)
• CUDA >= 11.0 and a Compute Capability >= 3.5 NVIDIA GPU.
• C++17 capable C++ compiler (host), compatible with the installed CUDA version
  • Microsoft Visual Studio 2019 or 2022 (Windows)
    • Note: Visual Studio must be installed before the CUDA toolkit is installed. See the CUDA installation guide for Windows for more information.
  • make and GCC >= 8.1 (Linux)
• git

Optionally:

• cpplint for linting code
• Doxygen to build the documentation
• Python >= 3.7 for python integration
  • With setuptools, wheel, build and optionally venv python packages installed
• swig >= 4.0.2 for python integration
  • Swig 4.x will be automatically downloaded by CMake if not provided (if possible).
• FLAMEGPU2-visualiser dependencies (fetched if possible)
  • SDL
  • GLM (consistent C++/GLSL vector maths functionality)
  • GLEW (GL extension loader)
  • FreeType (font loading)
  • DevIL (image loading)
  • Fontconfig (Linux only, font detection)

Building with CMake

Building via CMake is a three step process, with slight differences depending on your platform.

1. Create a build directory for an out-of tree build
2. Configure CMake into the build directory
   • Using the CMake GUI or CLI tools
   • Specifying build options such as the CUDA Compute Capabilities to target, the inclusion of Visualisation or Python components, or performance impacting features such as FLAMEGPU_SEATBELTS. See CMake Configuration Options for details of the available configuration options
   • CMake will automatically find and select compilers, libraries and python interpreters based on current environmental variables and default locations. See Mastering CMake for more information.
     • Python dependencies must be installed in the selected python environment. If needed you can instruct CMake to use a specific python implementation using the Python_ROOT_DIR and Python_Executable CMake options at configure time.
3. Build compilation targets using the configured build system
   • See Available Targets for a list of available targets.

Linux

To build under Linux using the command line, you can perform the following steps.

For example, to configure CMake for Release builds, for consumer Pascal GPUs (Compute Capability 61), with python bindings enabled, producing the static library and boids_bruteforce example binary.

# Create the build directory and change into it
mkdir -p build && cd build

# Configure CMake from the command line passing configure-time options. 
cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_CUDA_ARCHITECTURES=61 -DFLAMEGPU_BUILD_PYTHON=ON

# Build the required targets. In this case all targets
cmake --build . --target flamegpu boids_bruteforce -j 8

# Alternatively make can be invoked directly
make flamegpu boids_bruteforce -j8

Windows

Under Windows, you must instruct CMake on which Visual Studio and architecture to build for, using the CMake -A and -G options. This can be done through the GUI or the CLI.

I.e. to configure CMake for consumer Pascal GPUs (Compute Capability 61), with python bindings enabled, and build the producing the static library and boids_bruteforce example binary in the Release configuration:

REM Create the build directory 
mkdir build
cd build

REM Configure CMake from the command line, specifying the -A and -G options. Alternatively use the GUI
cmake .. -A x64 -G "Visual Studio 16 2019" -DCMAKE_CUDA_ARCHITECTURES=61 -DFLAMEGPU_BUILD_PYTHON=ON

REM You can then open Visual Studio manually from the .sln file, or via:
cmake --open . 
REM Alternatively, build from the command line specifying the build configuration
cmake --build . --config Release --target flamegpu boids_bruteforce --verbose

CMake Configuration Options

Option	Value	Description
CMAKE_BUILD_TYPE	Release / Debug / MinSizeRel / RelWithDebInfo	Select the build configuration for single-target generators such as make
CMAKE_CUDA_ARCHITECTURES	e.g 60, "60;70"	CUDA Compute Capabilities to build/optimise for, as a ; separated list. See CMAKE_CUDA_ARCHITECTURES. Defaults to all-major or equivalent. Alternatively use the CUDAARCHS environment variable.
FLAMEGPU_SEATBELTS	ON/OFF	Enable / Disable additional runtime checks which harm performance but increase usability. Default ON
FLAMEGPU_VISUALISATION	ON/OFF	Enable Visualisation. Default OFF.
FLAMEGPU_VISUALISATION_ROOT	path/to/vis	Provide a path to a local copy of the visualisation repository.
FLAMEGPU_ENABLE_NVTX	ON/OFF	Enable NVTX markers for improved profiling. Default OFF
FLAMEGPU_WARNINGS_AS_ERRORS	ON/OFF	Promote compiler/tool warnings to errors are build time. Default OFF
FLAMEGPU_RTC_EXPORT_SOURCES	ON/OFF	At runtime, export dynamic RTC files to disk. Useful for debugging RTC models. Default OFF
FLAMEGPU_RTC_DISK_CACHE	ON/OFF	Enable/Disable caching of RTC functions to disk. Default ON.
FLAMEGPU_VERBOSE_PTXAS	ON/OFF	Enable verbose PTXAS output during compilation. Default OFF.
FLAMEGPU_CURAND_ENGINE	XORWOW / PHILOX / MRG	Select the CUDA random engine. Default XORWOW
FLAMEGPU_ENABLE_GLM	ON/OFF	Experimental feature for GLM type support in RTC models. Default OFF.
FLAMEGPU_SHARE_USAGE_STATISTICS	ON/OFF	Share usage statistics (telemetry) to support evidencing usage/impact of the software. Default ON.
FLAMEGPU_TELEMETRY_SUPPRESS_NOTICE	ON/OFF	Suppress notice encouraging telemetry to be enabled, which is emitted once per binary execution if telemetry is disabled. Defaults to OFF, or the value of a system environment variable of the same name.

For a list of available CMake configuration options, run the following from the build directory:

cmake -LH ..

Available Targets

Target	Description
all	Linux target containing default set of targets, including everything but the documentation and lint targets
ALL_BUILD	The windows equivalent of all
flamegpu	Build FLAME GPU static library
template	Each individual flamegpu_add_executable has it's own target. I.e. template
all_lint	Run all available Linter targets

For a full list of available targets, run the following after configuring CMake:

cmake --build . --target help

Usage

Once compiled individual models can be executed from the command line, with a range of default command line arguments depending on whether the model implements a single Simulation, or an Ensemble of simulations.

To see the available command line arguments use the -h or --help options, for either C++ or python models.

I.e. for a Release build of the template model, run:

./bin/Release/template --help

Visual Studio

If wishing to run examples within Visual Studio it is necessary to right click the desired example in the Solution Explorer and select Debug > Start New Instance. Alternatively, if Set as StartUp Project is selected, the main debugging menus can be used to initiate execution. To configure command line argument for execution within Visual Studio, right click the desired example in the Solution Explorer and select Properties, in this dialog select Debugging in the left hand menu to display the entry field for command arguments. Note, it may be necessary to change the configuration as the properties dialog may be targeting a different configuration to the current build configuration.

Environment Variables

Several environmental variables are used or required by FLAME GPU 2.

Environment Variable	Description
CUDA_PATH	Required when using RunTime Compilation (RTC), pointing to the root of the CUDA Toolkit where NVRTC resides. i.e. /usr/local/cuda-11.0/ or C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v11.0. Alternatively CUDA_HOME may be used if CUDA_PATH was not set.
FLAMEGPU_INC_DIR	When RTC compilation is required, if the location of the include directory cannot be found it must be specified using the FLAMEGPU_INC_DIR environment variable.
FLAMEGPU_TMP_DIR	FLAME GPU may cache some files to a temporary directory on the system, using the temporary directory returned by std::filesystem::temp_directory_path. The location can optionally be overridden using the FLAMEGPU_TMP_DIR environment variable.
FLAMEGPU_RTC_INCLUDE_DIRS	A list of include directories that should be provided to the RTC compiler, these should be separated using ; (Windows) or : (Linux). If this variable is not found, the working directory will be used as a default.
FLAMEGPU_SHARE_USAGE_STATISTICS	Enable / Disable sending of telemetry data, when set to ON or OFF respectively.
FLAMEGPU_TELEMETRY_SUPPRESS_NOTICE	Enable / Disable a once per execution notice encouraging the use of telemetry, if telemetry is disabled, when set to ON or OFF respectively.

Usage Statistics (Telemetry)

Support for academic software is dependant on evidence of impact. Without evidence it is difficult/impossible to justify investment to add features and provide maintenance. We collect a minimal amount of anonymous usage data so that we can gather usage statistics that enable us to continue to develop the software under a free and permissible licence.

Information is collected when a simulation, ensemble or test suite run have completed.

The TelemetryDeck service is used to store telemetry data. All data is sent to their API endpoint of https://nom.telemetrydeck.com/v1/ via https. For more details please review the TelmetryDeck privacy policy.

We do not collect any personal data such as usernames, email addresses or machine identifiers.

More information can be found in the FLAMEGPU documentation.

Telemetry is enabled by default, but can be opted out by:

• Setting an environment variable FLAMEGPU_SHARE_USAGE_STATISTICS to OFF, false or 0 (case insensitive).
  • If this is set during the first CMake configuration it will be used for all subsequent CMake configurations until the CMake Cache is cleared, or it is manually changed.
  • If this is set during simulation, ensemble or test execution (i.e. runtime) it will also be respected
• Setting the FLAMEGPU_SHARE_USAGE_STATISTICS CMake option to OFF or another false-like CMake value, which will default telemetry to be off for executions.
• Programmatically overriding the default value by:
  • Calling flamegpu::io::Telemetry::disable() or pyflamegpu.Telemetry.disable() prior to the construction of any Simulation, CUDASimulation or CUDAEnsemble objects.
  • Setting the telemetry config property of a Simulation.Config, CUDASimulation.SimulationConfig or CUDAEnsemble.EnsembleConfig to false.

Authors and Acknowledgment

See Contributors for a list of contributors towards this project.

If you use this software in your work, please cite DOI 10.5281/zenodo.5428984. Release specific DOI are also provided via Zenodo.

Alternatively, CITATION.cff provides citation metadata, which can also be accessed from GitHub.

License

FLAME GPU is distributed under the MIT Licence.