When Enoki extracts packets or slices through custom data structures, it also
handles STL data structures including std::array, and std::pair, and
std::tuple. Please review the section on dynamic arrays
for general details on vectorizing over dynamic arrays and working with slices.
To use this feature, include the following header file:
#include <enoki/stl.h>
Consider the following example, where a function returns a std::tuple
containing a 3D position and a mask specifying whether the computation was
successful. When the enoki/stl.h header file is included, Enoki’s
dynamic vectorization machinery can be applied to vectorize such functions over
arbitrarily large inputs.
/// Return value of 'my_function'
template <typename T>
using Return = std::tuple<
Array<T, 3>,
mask_t<T>
>;
template <typename T> Return<T> my_function(T theta, T phi) {
/* Turn spherical -> cartesian coordinates */
Array<T, 3> pos(
sin(theta) * cos(phi),
sin(theta) * sin(phi),
cos(theta)
);
/* Only points on the top hemisphere are 'valid' */
return std::make_pair(pos, pos.z() > 0);
}
/// Packet of floats
using FloatP = Packet<float>;
/// Arbitrarily large sequence of floats
using FloatX = DynamicArray<FloatP>;
/// Tuple containing a packet of results
using ReturnP = Return<FloatP>;
/// Tuple containing dynamic arrays with arbitrarily many results
using ReturnX = Return<FloatX>;
int main(int argc, char *argv[]) {
FloatX theta = linspace<FloatX>(-10.f, 10.f, 10);
FloatX phi = linspace<FloatX>(0.f, 60.f, 10);
ReturnX result = vectorize(my_function<FloatP>, theta, phi);
/* Prints:
[[0.544021, 0, -0.839072],
[-0.924676, -0.373065, 0.0761302],
[0.478888, 0.461548, 0.746753],
[0.0777672, 0.173978, -0.981674],
[-0.0330365, -0.895583, 0.443666],
[-0.304446, 0.842896, 0.443666],
[0.127097, -0.141995, -0.981674],
[0.596782, -0.293616, 0.746753],
[-0.994388, 0.0734624, 0.0761293],
[0.518133, 0.165823, -0.839072]]
*/
std::cout << std::get<0>(result) << std::endl;
/* Prints:
[0, 0, 0, 0, 0, 1, 1, 1, 1, 1]
*/
std::cout << std::get<1>(result) << std::endl;
}