Importing predefined CAD models into GEANT4 is not always possible or requires intermediate file format conversion to Geometry Description Markup Language (GDML) using commercial or third party software. CADMesh is a direct CAD model import interface for GEANT4 leveraging ASSIMP for reading the CAD files. Currently it supports the import of triangular facet surface meshes defined in formats such as STL and PLY. A G4TessellatedSolid is returned and can be included in a standard user detector constructor. You can find the project page and a git repository here. The old Google Code page for CADMesh is still kept up-to-date, however future developments occur here on GitHub.
Additional functionality is included for the fast navigation of tessellated solids by automatically creating equivalent tetrahedral meshes thereby making smart voxelisation available for the solid.
CADMesh is described in a technical paper, available here. If you would like the cite the article, you may wish use the following bibtex entry:
@article{poole2012acad,
author = {Poole, C. M. and Cornelius, I. and Trapp, J. V. and Langton, C. M.},
title = {{A CAD Interface for GEANT4}},
journal={Australasian Physical & Engineering Science in Medicine},
year = 2012,
month = September,
doi = {10.1007/s13246-012-0159-8},
url = {http://www.springerlink.com/content/u563877422284578}
}
The fast tessellated solid navigation technique included in CADMesh is described here:
@article{poole2012fast,
title={Fast Tessellated Solid Navigation in GEANT4},
author={Poole, C. and Cornelius, I. and Trapp, J. and Langton, C.M.},
journal={IEEE Transactions on Nuclear Science},
volume={99},
pages={1--7},
year={2012},
publisher={Institute of Electrical and Electronics Engineers}
}
#Example Usage The following shows basic default usage for cadmesh in a UserDetectorConstruction:
// User Detector Constructor
#include "CADMesh.hh"
...
G4ThreeVector offset;
G4VSolid * cad_solid;
G4LogicalVolume * cad_logical;
G4VPhysicalVolume * cad_physical;
...
offset = G4ThreeVector(-30*cm, 0, 0);
CADMesh * mesh = new CADMesh("../../models/cone.ply", mm, offset, false);
cad_solid = mesh->TessellatedMesh();
cad_logical = new G4LogicalVolume(cad_solid, water, "cad_logical", 0, 0, 0);
cad_physical = new G4PVPlacement(0, G4ThreeVector(), cad_logical,
"cad_physical", world_logical, false, 0);
...
# CMakeLists.txt
cmake_minimum_required(VERSION 2.6 FATAL_ERROR)
project(cadmesh_example)
# GEANT4 core
find_package(Geant4 REQUIRED ui_all vis_all)
include(${Geant4_USE_FILE})
include_directories(${PROJECT_SOURCE_DIR}/include)
# CADMesh
find_package(cadmesh)
# User code
file(GLOB sources ${PROJECT_SOURCE_DIR}/src/*.cc)
file(GLOB headers ${PROJECT_SOURCE_DIR}/include/*.hh)
add_executable(cadmesh_example cadmesh_example.cc ${sources} ${headers})
target_link_libraries(cadmesh_example ${Geant4_LIBRARIES})
target_link_libraries(cadmesh_example ${cadmesh_LIBRARIES})
A working installation of the following libraries or packages is required:
They are included in the repository as external projects/submodules.
Download the latest release of CADMesh from the Downloads section, and extract the archive, or checkout the development branch from the repository.
# CADMesh latest dev branch
git clone https://github.com/christopherpoole/CADMesh.git
# OR download a release from https://github.com/christopherpoole/CADMesh/releases, and extract the download somewhere.
cd cadmesh/
# Fetch the external dependancies (optional), running
# cmake will result in this happening anyway.
# git submodule update --init --recursive
mkdir build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX:PATH=<optional install location>
sudo make install
Here is a basic example usage. The CMakeLists.txt file illustrates how to link against CADMesh (which requires CADMesh to be installed somewhere).
# Run example (Linux with g++)
cd examples/basic
mkdir build
cd build
cmake .. -Dcadmesh_DIR:PATH=<cadmesh install location>
make
./cadmesh_example <macro> <cad file name> <cad file type, optional>
# Still in the build directory:
./cadmesh_example ../macros/vis.mac ../../../models/cone.ply
Idle> exit
# To use the tetrahedram meshing as well (tetgen needs to know the file type):
./cadmesh_example ../macros/vis.mac ../../../models/cone.ply PLY
If you get an error such as this:
./build/cadmesh_example: error while loading shared libraries: libcadmesh.so: cannot open shared object file: No such file or directory
Make sure the CADMesh library is in your path:
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:<cadmesh install location>/lib
or on a Mac:
export DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:<cadmesh install location>/lib