Point Cloud Library (PCL)  1.12.0
approx_nearest_utils.hpp
1 /*
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Point Cloud Library (PCL) - www.pointclouds.org
5  * Copyright (c) 2020-, Open Perception
6  *
7  * All rights reserved
8  */
9 
10 #pragma once
11 
12 #include "morton.hpp"
13 #include <assert.h>
14 
15 #include <limits>
16 #include <tuple>
17 #include <bitset>
18 
19 namespace pcl {
20 namespace device {
21 
22 __device__ __host__ __forceinline__ unsigned
23 getBitsNum(const unsigned integer)
24 {
25  #ifdef __CUDA_ARCH__
26  return __popc(integer);
27  #else
28  return std::bitset<8*sizeof(integer)> (integer).count();
29  #endif
30 }
31 
32 __host__ __device__ __forceinline__ std::pair<uint3, std::uint8_t>
33 nearestVoxel(const float3 query,
34  const unsigned& level,
35  const std::uint8_t& mask,
36  const float3& minp,
37  const float3& maxp,
38  const uint3& index)
39 {
40  assert(mask != 0);
41  // identify closest voxel
42  float closest_distance = std::numeric_limits<float>::max();
43  unsigned closest_index = 0;
44  uint3 closest = make_uint3(0, 0, 0);
45 
46  for (unsigned i = 0; i < 8; ++i) {
47  if ((mask & (1 << i)) == 0) // no child
48  continue;
49 
50  const uint3 child = make_uint3((index.x << 1) + (i & 1),
51  (index.y << 1) + ((i >> 1) & 1),
52  (index.z << 1) + ((i >> 2) & 1));
53 
54  // find center of child cell
55  const unsigned voxel_width_scale_factor = 1 << (level + 2);
56  const float3 voxel_center =
57  make_float3(minp.x + (maxp.x - minp.x) * (2 * child.x + 1) / voxel_width_scale_factor,
58  minp.y + (maxp.y - minp.y) * (2 * child.y + 1) / voxel_width_scale_factor,
59  minp.z + (maxp.z - minp.z) * (2 * child.z + 1) / voxel_width_scale_factor);
60 
61  // compute distance to centroid
62  const float3 dist = make_float3(
63  voxel_center.x - query.x, voxel_center.y - query.y, voxel_center.z - query.z);
64 
65  const float distance_to_query = dist.x * dist.x + dist.y * dist.y + dist.z * dist.z;
66 
67  // compare distance
68  if (distance_to_query < closest_distance) {
69  closest_distance = distance_to_query;
70  closest_index = i;
71  closest = child;
72  }
73  }
74 
75  return {closest, 1 << closest_index};
76 }
77 
78 #pragma hd_warning_disable
79 template <typename T>
80 __device__ __host__ int
81 findNode(const float3 minp, const float3 maxp, const float3 query, const T nodes)
82 {
83  size_t node_idx = 0;
84  const auto code = CalcMorton(minp, maxp)(query);
85  unsigned level = 0;
86 
87  bool voxel_traversal = false;
88  uint3 index = Morton::decomposeCode(code);
89  std::uint8_t mask_pos;
90 
91  while (true) {
92  const auto node = nodes[node_idx];
93  const std::uint8_t mask = node & 0xFF;
94 
95  if (!mask) // leaf
96  return node_idx;
97 
98  if (voxel_traversal) // empty voxel already encountered, performing nearest-centroid
99  // based traversal
100  {
101  const auto nearest_voxel = nearestVoxel(query, level, mask, minp, maxp, index);
102  index = nearest_voxel.first;
103  mask_pos = nearest_voxel.second;
104  }
105  else {
106  mask_pos = 1 << Morton::extractLevelCode(code, level);
107 
108  if (!(mask & mask_pos)) // child doesn't exist
109  {
110  const auto remaining_depth = Morton::levels - level;
111  index.x >>= remaining_depth;
112  index.y >>= remaining_depth;
113  index.z >>= remaining_depth;
114 
115  voxel_traversal = true;
116  const auto nearest_voxel = nearestVoxel(query, level, mask, minp, maxp, index);
117  index = nearest_voxel.first;
118  mask_pos = nearest_voxel.second;
119  }
120  }
121  node_idx = (node >> 8) + getBitsNum(mask & (mask_pos - 1));
122  ++level;
123  }
124 }
125 } // namespace device
126 } // namespace pcl
__device__ __host__ int findNode(const float3 minp, const float3 maxp, const float3 query, const T nodes)
__device__ __host__ __forceinline__ unsigned getBitsNum(const unsigned integer)
__host__ __device__ __forceinline__ std::pair< uint3, std::uint8_t > nearestVoxel(const float3 query, const unsigned &level, const std::uint8_t &mask, const float3 &minp, const float3 &maxp, const uint3 &index)
__device__ __host__ static __forceinline__ void decomposeCode(code_t code, int &cell_x, int &cell_y, int &cell_z)
Definition: morton.hpp:84
__host__ __device__ static __forceinline__ code_t extractLevelCode(code_t code, int level)
Definition: morton.hpp:98
static const int levels
Definition: morton.hpp:47