##Repository Purpose##

To create a prototype and minimal-viable-product for the next generation of virtual instruments. This repository specifically looks at novel approaches to virtual instrument representations for high-throughput data reduction from neutron scattering experiments. A major requirement is the ability to rapidly extract key detector information required for data reduction. See requirements for more context.

This repository is designed to host several prototypes aiming for the same purposes.

##What we expect the prototypes to do##

A distilled version of the requirements that the prototypes should address:

• Changing some part of the instrument geometry should not result in a deep copy.
• Allow each component to have a "shape" where each the shape can be shared across possibly 100,000's pixels but interrogating the location of the shape produces its "real" position
• Store key/value pairs (limited allowed types is fine) against a component. We need to handle cases where a parameter value is set across either a composite component or the whole instrument, e.g. He3 pressure in a tube. The lookup in this cases would still be through the leaf component so the client is unaware that it is shared but we don't create potentially a great many entries that are the same. The lookup for this still needs to be reasonably quick, e.g. accessing efixed for a given component in Indirect mode during ConvertUnits.
• Fast access to frequently-queried geometry quantities such as l1, l2, theta, phi (essentially what would be in a .dat file)

##Building the prototype##

CMake is required to configure the prototype.

GoogleTest is required to build the prototype, and must be downloaded and built separately:

$ git clone https://github.com/google/googletest.git
$ cd googletest
$ cmake .
$ cmake --build

GoogleBench is required, and should be built in a similar way to googletest:

$ git clone https://github.com/google/benchmark.git
$ cd benchmark
$ cmake .
$ cmake --build

Eigen is required, but is header only, so no build is necessary.

$ hg clone http://bitbucket.org/eigen/eigen

There are several variables that may need to be set when configuring the prototype: GTEST_SOURCE_DIR, GTEST_BUILD_DIR, GBENCH_BUILD_DIR, GBENCH_SOURCE_DIR, EIGEN_ADDITIONAL_SEARCH_PATHS.

GTEST_SOURCE_DIR should be the path to the googletest topmost directory. GTEST_BUILD_DIR should be the path to the googletest build directory (will be the same as GTEST_SOURCE_DIR in case of in-source builds). GBENCH_SOURCE_DIR should be the path to the googlebenchmark topmost directory containing the toplevel CMakeLists.txt. GBENCH_BUILD_DIR should be the path to the googlebench build directory, containing CMakeCache.txt. EIGEN_ADDITIONAL_SEARCH_PATHS should be the path to the topmost eigen source directory. The respective projects are located here for googletest, here for google benchmark, here for eigen.

GBench and GTest Variables mentioned above have defaults that assume googletest was built in-source (as shown above) and is adjacent to instrument-prototype. For example:

- Dev
|-- googletest
|-- googlebench
|-- instrument-prototype

If this is not how your directories are set up, or if you built googletest or googlebench as an out of source build, you will need to provide those variables to CMake when configuring the prototype. This can be done via the GUI or the commandline, e.g.:

$ git clone https://github.com/DMSC-Instrument-Data/instrument-prototype.git
$ cd instrument-prototype
$ mkdir build
$ cd build
$ cmake -DGTEST_SOURCE_DIR="{path_to_gtest_source}" -DGTEST_BUILD_DIR="{path_to_gtest_build}" -DGBENCH_SOURCE_DIR={path_to_gbench_source} -DGBENCH_BUILD_DIR="{path_to_gbench_build}" -DEIGEN_ADDITIONAL_SEARCH_PATHS="{path_to_eigen_source}"
$ make

CMake will issue an error if the directories are incorrect (if it cannot find the include/library files required).

You may also inspect the .travis.yml file associated with this prototype to see individual steps for the build.

Homebrew

If you are using homebrew on OSX

brew install gcc
brew install boost --with-mpi --without-single --c++11
brew install mpi

prior to running cmake.

Trusty

For required trusty pacakges see *before_install* in [.travis.yml](.travis.yml)