ОП уже ответил на этот вопрос самостоятельно.Тем не менее, было бы хорошо сказать, что Thrust уже имеет пример конструкции Bounding Box, хотя ограничен 2D, см. Пример Thrust Bounding Box .
Ниже я предоставляютрехмерное расширение этого примера, в котором используется float3 вместо настроенной в нем point2d структуры.
#include <thrust/transform_reduce.h>
#include <thrust/device_vector.h>
#include <thrust/pair.h>
#include <thrust/random.h>
#include <thrust/extrema.h>
/***********************/
/* BOUNDING BOX STRUCT */
/***********************/
struct bbox
{
float3 lower_left, upper_right;
// --- Empty box constructor
__host__ __device__ bbox() {}
// --- Construct a box from a single point
__host__ __device__ bbox(const float3 &point) : lower_left(point), upper_right(point) {}
// --- Construct a box from a pair of points
__host__ __device__ bbox(const float3 &ll, const float3 &ur) : lower_left(ll), upper_right(ur) {}
};
/*********************************/
/* BOUNDING BOX REDUCTION STRUCT */
/*********************************/
// --- Reduce a pair of bounding boxes (a, b) to a bounding box containing a and b
struct bbox_reduction : public thrust::binary_function<bbox, bbox, bbox>
{
__host__ __device__ bbox operator()(bbox a, bbox b)
{
// --- Lower left corner
float3 ll = make_float3(thrust::min(a.lower_left.x, b.lower_left.x), thrust::min(a.lower_left.y, b.lower_left.y), thrust::min(a.lower_left.z, b.lower_left.z));
// --- Upper right corner
float3 ur = make_float3(thrust::max(a.upper_right.x, b.upper_right.x), thrust::max(a.upper_right.y, b.upper_right.y), thrust::max(a.upper_right.z, b.upper_right.z));
return bbox(ll, ur);
}
};
/********/
/* MAIN */
/********/
int main(void)
{
const size_t N = 40;
thrust::default_random_engine rng;
thrust::uniform_real_distribution<float> u01(0.0f, 1.0f);
// --- Allocate space for 3D points
thrust::device_vector<float3> d_points(N);
// --- Generate random 3D points in the unit cube
for (size_t i = 0; i < N; i++)
{
float x = u01(rng);
float y = u01(rng);
float z = u01(rng);
d_points[i] = make_float3(x, y, z);
}
// --- The initial bounding box contains the first point of the point cloud
bbox init = bbox(d_points[0], d_points[0]);
// --- Binary reduction operation
bbox_reduction binary_op;
// --- Compute the bounding box for the point set
bbox result = thrust::reduce(d_points.begin(), d_points.end(), init, binary_op);
for (int k = 0; k < N; k++) {
float3 temp = d_points[k];
printf("%d %f %f %f\n", k, temp.x, temp.y, temp.z);
}
// --- Print output
std::cout << "bounding box " << std::fixed;
std::cout << "(" << result.lower_left.x << "," << result.lower_left.y << "," << result.lower_left.z << ") ";
std::cout << "(" << result.upper_right.x << "," << result.upper_right.y << "," << result.upper_right.z << ")" << std::endl;
return 0;
}