particleGen.hpp

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// -------------------------------------------------------//
//
// SHAMROCK code for hydrodynamics
// Copyright (c) 2021-2026 Timothée David--Cléris <tim.shamrock@proton.me>
// SPDX-License-Identifier: CeCILL Free Software License Agreement v2.1
// Shamrock is licensed under the CeCILL 2.1 License, see LICENSE for more information
//
// -------------------------------------------------------//
 
#pragma once
 
#include "shambackends/sycl_utils.hpp"
#include "shambackends/vec.hpp"
#include <functional>
#include <vector>
 
namespace shamrock::sph {
 
    template<class flt>
    inline sycl::vec<flt, 3> get_box_dim(flt r_particle, u32 xcnt, u32 ycnt, u32 zcnt) {
 
        using vec3 = sycl::vec<flt, 3>;
 
        u32 im = xcnt;
        u32 jm = ycnt;
        u32 km = zcnt;
 
        auto get_pos = [&](u32 i, u32 j, u32 k) -> vec3 {
            vec3 r_a
                = {2 * i + ((j + k) % 2),
                   sycl::sqrt(3.) * (j + (1. / 3.) * (k % 2)),
                   2 * sycl::sqrt(6.) * k / 3};
 
            r_a *= r_particle;
 
            return r_a;
        };
 
        return get_pos(im, jm, km);
    }
 
    template<class flt>
    inline std::tuple<sycl::vec<flt, 3>, sycl::vec<flt, 3>> get_ideal_fcc_box(
        flt r_particle, std::tuple<sycl::vec<flt, 3>, sycl::vec<flt, 3>> box) {
 
        using vec3 = sycl::vec<flt, 3>;
 
        vec3 box_min = std::get<0>(box);
        vec3 box_max = std::get<1>(box);
 
        vec3 box_dim = box_max - box_min;
 
        vec3 iboc_dim = (box_dim / vec3({2, sycl::sqrt(3.), 2 * sycl::sqrt(6.) / 3})) / r_particle;
 
        u32 i = iboc_dim.x();
        u32 j = iboc_dim.y();
        u32 k = iboc_dim.z();
 
        // std::cout << "get_ideal_box_idim :" << i << " " << j << " " << k << std::endl;
 
        i -= i % 2;
        j -= j % 2;
        k -= k % 2;
 
        vec3 m1 = get_box_dim(r_particle, i, j, k);
 
        return {box_min, box_min + m1};
    }
 
    template<class Tscal>
    inline sycl::vec<Tscal, 3> get_fcc_pos(u32 i, u32 j, u32 k) {
        return {
            2 * i + ((j + k) % 2),
            sycl::sqrt(3.) * (j + (1. / 3.) * (k % 2)),
            2 * sycl::sqrt(6.) * k / 3};
    }
 
} // namespace shamrock::sph