2.3 KiB
Added ArrayHandleSOA
ArrayHandleSOA behaves like a regular ArrayHandle (with a basic
storage) except that if you specify a ValueType of a Vec or a
Vec-like, it will actually store each component in a separate physical
array. When data are retrieved from the array, they are reconstructed into
Vec objects as expected.
The intention of this array type is to help cover the most common ways data
is lain out in memory. Typically, arrays of data are either an "array of
structures" like the basic storage where you have a single array of
structures (like Vec) or a "structure of arrays" where you have an array
of a basic type (like float) for each component of the data being
represented. The ArrayHandleSOA makes it easy to cover this second case
without creating special types.
ArrayHandleSOA can be constructed from a collection of ArrayHandle with
basic storage. This allows you to construct Vec arrays from components
without deep copies.
std::vector<vtkm::Float32> accel0;
std::vector<vtkm::Float32> accel1;
std::vector<vtkm::Float32> accel2;
// Let's say accel arrays are set to some field of acceleration vectors by
// some other software.
vtkm::cont::ArrayHandle<vtkm::Float32> accelHandle0 = vtkm::cont::make_ArrayHandle(accel0);
vtkm::cont::ArrayHandle<vtkm::Float32> accelHandle1 = vtkm::cont::make_ArrayHandle(accel1);
vtkm::cont::ArrayHandle<vtkm::Float32> accelHandle2 = vtkm::cont::make_ArrayHandle(accel2);
vtkm::cont::ArrayHandleSOA<vtkm::Vec3f_32> accel = { accelHandle0, accelHandle1, accelHandle2 };
Also provided are constructors and versions of make_ArrayHandleSOA that
take std::vector or C arrays as either initializer lists or variable
arguments.
std::vector<vtkm::Float32> accel0;
std::vector<vtkm::Float32> accel1;
std::vector<vtkm::Float32> accel2;
// Let's say accel arrays are set to some field of acceleration vectors by
// some other software.
vtkm::cont::ArrayHandleSOA<vtkm::Vec3f_32> accel = { accel0, accel1, accel2 };
However, setting arrays is a little awkward because you also have to specify the length. This is done either outside the initializer list or as the first argument.
vtkm::cont::make_ArrayHandleSOA({ array0, array1, array2 }, ARRAY_SIZE);
vtkm::cont::make_ArrayHandleSOA(ARRAY_SIZE, array0, array1, array2);