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Update assign_particles_to_cells to also assign cells to particles

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This commit is contained in:
Alex Selimov 2025-09-26 15:37:43 -04:00
parent ca852c8a51
commit 0eeb9d305e
Signed by: aselimov
GPG key ID: 3DDB9C3E023F1F31
1 changed files with 26 additions and 4 deletions
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30
kernels/neighbor_list.cuh
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@ -6,6 +6,8 @@
#include "utils.cuh"
#include <cuda_runtime.h>
#include <thrust/device_vector.h>
#include <thrust/iterator/constant_iterator.h>
#include <thrust/iterator/discard_iterator.h>
#include <thrust/pair.h>
#include <thrust/sequence.h>
#include <thrust/sort.h>
@ -76,20 +78,40 @@ struct CellList {
return std::make_pair(grid_size, cell_size);
}
__device__ int3 get_cell_coords_from_position(float3 pos) const {
__host__ __device__ int3 get_cell_coords_from_position(float3 pos) const {
return make_int3((int)((pos.x - box_min.x) / cell_size.x),
(int)((pos.y - box_min.y) / cell_size.y),
(int)((pos.z - box_min.z) / cell_size.z));
}
__device__ int get_cell_index_from_position(float3 pos) const {
__host__ __device__ int get_cell_index_from_position(float3 pos) const {
return get_cell_index_from_cell_coords(get_cell_coords_from_position(pos));
}
__device__ void assign_particles_to_cells(float3 *positions) {
for (int i = 0; i < this->n_particles; i++) {
void assign_particles_to_cells(float3 *positions) {
thrust::device_ptr<int> particle_cells_ptr(particle_cells);
thrust::device_ptr<int> sorted_particles_ptr(sorted_particles);
thrust::device_ptr<int> cell_starts_ptr(cell_starts);
thrust::device_ptr<int> cell_count_ptr(cell_count);
thrust::sequence(sorted_particles_ptr, sorted_particles_ptr + n_particles);
for (size_t i = 0; i < n_particles; i++) {
particle_cells[i] = get_cell_index_from_position(positions[i]);
}
thrust::sort_by_key(particle_cells_ptr, particle_cells_ptr + n_particles,
sorted_particles_ptr);
thrust::fill(cell_starts_ptr, cell_starts_ptr + total_cells, 0);
thrust::fill(cell_count_ptr, cell_count_ptr + total_cells, 0);
thrust::reduce_by_key(particle_cells_ptr, particle_cells_ptr + n_particles,
thrust::constant_iterator<int>(1),
thrust::discard_iterator(), cell_count_ptr);
thrust::exclusive_scan(cell_count_ptr, cell_count_ptr + total_cells,
cell_starts_ptr);
}
};