OpenVDB: openvdb/points/PointScatter.h Source File

OpenVDB 10.0.1

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PointScatter.h
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1// Copyright Contributors to the OpenVDB Project
2// SPDX-License-Identifier: MPL-2.0
3
4/// @author Nick Avramoussis
5///
6/// @file points/PointScatter.h
7///
8/// @brief Various point scattering methods for generating VDB Points.
9///
10/// All random number calls are made to the same generator to produce
11/// temporarily consistent results in relation to the provided seed. This
12/// comes with some multi-threaded performance trade-offs.
13
14#ifndef OPENVDB_POINTS_POINT_SCATTER_HAS_BEEN_INCLUDED
15#define OPENVDB_POINTS_POINT_SCATTER_HAS_BEEN_INCLUDED
16
17#include <type_traits>
18#include <algorithm>
19#include <thread>
20#include <random>
21
22#include <openvdb/openvdb.h>
23#include <openvdb/Types.h>
24#include <openvdb/tree/LeafManager.h>
25#include <openvdb/tools/Prune.h>
26#include <openvdb/util/NullInterrupter.h>
27
28#include "AttributeArray.h"
29#include "PointCount.h"
30#include "PointDataGrid.h"
31
32#include <tbb/parallel_sort.h>
33#include <tbb/parallel_for.h>
34
35namespace openvdb {
36 OPENVDB_USE_VERSION_NAMESPACE
37namespace OPENVDB_VERSION_NAME {
38namespace points {
39
40/// @brief The free functions depend on the following class:
41///
42/// The @c InterrupterT template argument below refers to any class
43/// with the following interface:
44/// @code
45/// class Interrupter {
46/// ...
47/// public:
48/// void start(const char* name = nullptr) // called when computations begin
49/// void end() // called when computations end
50/// bool wasInterrupted(int percent=-1) // return true to break computation
51///};
52/// @endcode
53///
54/// @note If no template argument is provided for this InterrupterT
55/// the util::NullInterrupter is used which implies that all
56/// interrupter calls are no-ops (i.e. incurs no computational overhead).
57
58
59/// @brief Uniformly scatter a total amount of points in active regions
60///
61/// @param grid A source grid. The resulting PointDataGrid will copy this grids
62/// transform and scatter in its active voxelized topology.
63/// @param count The total number of points to scatter
64/// @param seed A seed for the RandGenT
65/// @param spread The spread of points as a scale from each voxels center. A value of
66/// 1.0f indicates points can be placed anywhere within the voxel, where
67/// as a value of 0.0f will force all points to be created exactly at the
68/// centers of each voxel.
69/// @param interrupter An optional interrupter
70/// @note returns the scattered PointDataGrid
71template<
72 typename GridT,
73 typename RandGenT = std::mt19937,
74 typename PositionArrayT = TypedAttributeArray<Vec3f, NullCodec>,
75 typename PointDataGridT = Grid<
76 typename points::TreeConverter<typename GridT::TreeType>::Type>,
77 typename InterrupterT = util::NullInterrupter>
78inline typename PointDataGridT::Ptr
79 uniformPointScatter(const GridT& grid,
80 const Index64 count,
81 const unsigned int seed = 0,
82 const float spread = 1.0f,
83 InterrupterT* interrupter = nullptr);
84
85/// @brief Uniformly scatter a fixed number of points per active voxel. If the pointsPerVoxel
86/// value provided is a fractional value, each voxel calculates a delta value of
87/// how likely it is to contain an extra point.
88///
89/// @param grid A source grid. The resulting PointDataGrid will copy this grids
90/// transform and scatter in its active voxelized topology.
91/// @param pointsPerVoxel The number of points to scatter per voxel
92/// @param seed A seed for the RandGenT
93/// @param spread The spread of points as a scale from each voxels center. A value of
94/// 1.0f indicates points can be placed anywhere within the voxel, where
95/// as a value of 0.0f will force all points to be created exactly at the
96/// centers of each voxel.
97/// @param interrupter An optional interrupter
98/// @note returns the scattered PointDataGrid
99
100template<
101 typename GridT,
102 typename RandGenT = std::mt19937,
103 typename PositionArrayT = TypedAttributeArray<Vec3f, NullCodec>,
104 typename PointDataGridT = Grid<
105 typename points::TreeConverter<typename GridT::TreeType>::Type>,
106 typename InterrupterT = util::NullInterrupter>
107inline typename PointDataGridT::Ptr
108 denseUniformPointScatter(const GridT& grid,
109 const float pointsPerVoxel,
110 const unsigned int seed = 0,
111 const float spread = 1.0f,
112 InterrupterT* interrupter = nullptr);
113
114/// @brief Non uniformly scatter points per active voxel. The pointsPerVoxel value is used
115/// to weight each grids cell value to compute a fixed number of points for every
116/// active voxel. If the computed result is a fractional value, each voxel calculates
117/// a delta value of how likely it is to contain an extra point.
118///
119/// @param grid A source grid. The resulting PointDataGrid will copy this grids
120/// transform, voxelized topology and use its values to compute a
121/// target points per voxel. The grids ValueType must be convertible
122/// to a scalar value. Only active and larger than zero values will
123/// contain points.
124/// @param pointsPerVoxel The number of points to scatter per voxel
125/// @param seed A seed for the RandGenT
126/// @param spread The spread of points as a scale from each voxels center. A value of
127/// 1.0f indicates points can be placed anywhere within the voxel, where
128/// as a value of 0.0f will force all points to be created exactly at the
129/// centers of each voxel.
130/// @param interrupter An optional interrupter
131/// @note returns the scattered PointDataGrid
132template<
133 typename GridT,
134 typename RandGenT = std::mt19937,
135 typename PositionArrayT = TypedAttributeArray<Vec3f, NullCodec>,
136 typename PointDataGridT = Grid<
137 typename points::TreeConverter<typename GridT::TreeType>::Type>,
138 typename InterrupterT = util::NullInterrupter>
139inline typename PointDataGridT::Ptr
140 nonUniformPointScatter(const GridT& grid,
141 const float pointsPerVoxel,
142 const unsigned int seed = 0,
143 const float spread = 1.0f,
144 InterrupterT* interrupter = nullptr);
145
146
147////////////////////////////////////////
148
149/// @cond OPENVDB_DOCS_INTERNAL
150
151namespace point_scatter_internal
152{
153
154/// @brief initialise the topology of a PointDataGrid and ensure
155/// everything is voxelized
156/// @param grid The source grid from which to base the topology generation
157template<typename PointDataGridT, typename GridT>
158inline typename PointDataGridT::Ptr
159initialisePointTopology(const GridT& grid)
160{
161 typename PointDataGridT::Ptr points(new PointDataGridT);
162 points->setTransform(grid.transform().copy());
163 points->topologyUnion(grid);
164 if (points->tree().hasActiveTiles()) {
165 points->tree().voxelizeActiveTiles();
166 }
167
168 return points;
169}
170
171/// @brief Generate random point positions for a leaf node
172/// @param leaf The leaf node to initialize
173/// @param descriptor The descriptor containing the position type
174/// @param count The number of points to generate
175/// @param spread The spread of points from the voxel center
176/// @param rand01 The random number generator, expected to produce floating point
177/// values between 0 and 1.
178template<typename PositionType,
179 typename CodecT,
180 typename RandGenT,
181 typename LeafNodeT>
182inline void
183generatePositions(LeafNodeT& leaf,
184 const AttributeSet::Descriptor::Ptr& descriptor,
185 const Index64& count,
186 const float spread,
187 RandGenT& rand01)
188{
189 using PositionTraits = VecTraits<PositionType>;
190 using ValueType = typename PositionTraits::ElementType;
191 using PositionWriteHandle = AttributeWriteHandle<PositionType, CodecT>;
192
193 leaf.initializeAttributes(descriptor, static_cast<Index>(count));
194
195 // directly expand to avoid needlessly setting uniform values in the
196 // write handle
197 auto& array = leaf.attributeArray(0);
198 array.expand(/*fill*/false);
199
200 PositionWriteHandle pHandle(array, /*expand*/false);
201 PositionType P;
202 for (Index64 index = 0; index < count; ++index) {
203 P[0] = (spread * (rand01() - ValueType(0.5)));
204 P[1] = (spread * (rand01() - ValueType(0.5)));
205 P[2] = (spread * (rand01() - ValueType(0.5)));
206 pHandle.set(static_cast<Index>(index), P);
207 }
208}
209
210} // namespace point_scatter_internal
211
212/// @endcond
213
214////////////////////////////////////////
215
216
217template<
218 typename GridT,
219 typename RandGenT,
220 typename PositionArrayT,
221 typename PointDataGridT,
222 typename InterrupterT>
223inline typename PointDataGridT::Ptr
224uniformPointScatter(const GridT& grid,
225 const Index64 count,
226 const unsigned int seed,
227 const float spread,
228 InterrupterT* interrupter)
229{
230 using PositionType = typename PositionArrayT::ValueType;
231 using PositionTraits = VecTraits<PositionType>;
232 using ValueType = typename PositionTraits::ElementType;
233 using CodecType = typename PositionArrayT::Codec;
234
235 using RandomGenerator = math::Rand01<ValueType, RandGenT>;
236
237 using TreeType = typename PointDataGridT::TreeType;
238 using LeafNodeType = typename TreeType::LeafNodeType;
239 using LeafManagerT = tree::LeafManager<TreeType>;
240
241 struct Local
242 {
243 /// @brief Get the prefixed voxel counts for each leaf node with an
244 /// additional value to represent the end voxel count.
245 /// See also LeafManager::getPrefixSum()
246 static void getPrefixSum(LeafManagerT& leafManager,
247 std::vector<Index64>& offsets)
248 {
249 Index64 offset = 0;
250 offsets.reserve(leafManager.leafCount() + 1);
251 offsets.push_back(0);
252 const auto leafRange = leafManager.leafRange();
253 for (auto leaf = leafRange.begin(); leaf; ++leaf) {
254 offset += leaf->onVoxelCount();
255 offsets.push_back(offset);
256 }
257 }
258 };
259
260 static_assert(PositionTraits::IsVec && PositionTraits::Size == 3,
261 "Invalid Position Array type.");
262
263 if (spread < 0.0f || spread > 1.0f) {
264 OPENVDB_THROW(ValueError, "Spread must be between 0 and 1.");
265 }
266
267 if (interrupter) interrupter->start("Uniform scattering with fixed point count");
268
269 typename PointDataGridT::Ptr points =
270 point_scatter_internal::initialisePointTopology<PointDataGridT>(grid);
271 TreeType& tree = points->tree();
272 if (!tree.cbeginLeaf()) return points;
273
274 LeafManagerT leafManager(tree);
275 const Index64 voxelCount = leafManager.activeLeafVoxelCount();
276 assert(voxelCount != 0);
277
278 const double pointsPerVolume = double(count) / double(voxelCount);
279 const Index32 pointsPerVoxel = static_cast<Index32>(math::RoundDown(pointsPerVolume));
280 const Index64 remainder = count - (pointsPerVoxel * voxelCount);
281
282 if (remainder == 0) {
283 return denseUniformPointScatter<
284 GridT, RandGenT, PositionArrayT, PointDataGridT, InterrupterT>(
285 grid, float(pointsPerVoxel), seed, spread, interrupter);
286 }
287
288 std::vector<Index64> voxelOffsets, values;
289 std::thread worker(&Local::getPrefixSum, std::ref(leafManager), std::ref(voxelOffsets));
290
291 {
292 math::RandInt<Index64, RandGenT> gen(seed, 0, voxelCount-1);
293 values.reserve(remainder);
294 for (Index64 i = 0; i < remainder; ++i) values.emplace_back(gen());
295 }
296
297 worker.join();
298
299 if (util::wasInterrupted<InterrupterT>(interrupter)) {
300 tree.clear();
301 return points;
302 }
303
304 tbb::parallel_sort(values.begin(), values.end());
305 const bool fractionalOnly(pointsPerVoxel == 0);
306
307 leafManager.foreach([&voxelOffsets, &values, fractionalOnly]
308 (LeafNodeType& leaf, const size_t idx)
309 {
310 const Index64 lowerOffset = voxelOffsets[idx]; // inclusive
311 const Index64 upperOffset = voxelOffsets[idx + 1]; // exclusive
312 assert(upperOffset > lowerOffset);
313
314 const auto valuesEnd = values.end();
315 auto lower = std::lower_bound(values.begin(), valuesEnd, lowerOffset);
316
317 auto* const data = leaf.buffer().data();
318 auto iter = leaf.beginValueOn();
319
320 Index32 currentOffset(0);
321 bool addedPoints(!fractionalOnly);
322 while (lower != valuesEnd) {
323 const Index64 vId = *lower;
324 if (vId >= upperOffset) break;
325
326 const Index32 nextOffset = Index32(vId - lowerOffset);
327 iter.increment(nextOffset - currentOffset);
328 currentOffset = nextOffset;
329 assert(iter);
330
331 auto& value = data[iter.pos()];
332 value = value + 1; // no += operator support
333 addedPoints = true;
334 ++lower;
335 }
336
337 // deactivate this leaf if no points were added. This will speed up
338 // the unthreaded rng
339 if (!addedPoints) leaf.setValuesOff();
340 });
341
342 voxelOffsets.clear();
343 values.clear();
344
345 if (fractionalOnly) {
346 tools::pruneInactive(tree);
347 leafManager.rebuild();
348 }
349
350 const AttributeSet::Descriptor::Ptr descriptor =
351 AttributeSet::Descriptor::create(PositionArrayT::attributeType());
352 RandomGenerator rand01(seed);
353
354 const auto leafRange = leafManager.leafRange();
355 auto leaf = leafRange.begin();
356 for (; leaf; ++leaf) {
357 if (util::wasInterrupted<InterrupterT>(interrupter)) break;
358 Index32 offset(0);
359 for (auto iter = leaf->beginValueAll(); iter; ++iter) {
360 if (iter.isValueOn()) {
361 const Index32 value = Index32(pointsPerVolume + Index32(*iter));
362 if (value == 0) leaf->setValueOff(iter.pos());
363 else offset += value;
364 }
365 // @note can't use iter.setValue(offset) on point grids
366 leaf->setOffsetOnly(iter.pos(), offset);
367 }
368
369 // offset should always be non zero
370 assert(offset != 0);
371 point_scatter_internal::generatePositions<PositionType, CodecType>
372 (*leaf, descriptor, offset, spread, rand01);
373 }
374
375 // if interrupted, remove remaining leaf nodes
376 if (leaf) {
377 for (; leaf; ++leaf) leaf->setValuesOff();
378 tools::pruneInactive(tree);
379 }
380
381 if (interrupter) interrupter->end();
382 return points;
383}
384
385
386////////////////////////////////////////
387
388
389template<
390 typename GridT,
391 typename RandGenT,
392 typename PositionArrayT,
393 typename PointDataGridT,
394 typename InterrupterT>
395inline typename PointDataGridT::Ptr
396denseUniformPointScatter(const GridT& grid,
397 const float pointsPerVoxel,
398 const unsigned int seed,
399 const float spread,
400 InterrupterT* interrupter)
401{
402 using PositionType = typename PositionArrayT::ValueType;
403 using PositionTraits = VecTraits<PositionType>;
404 using ValueType = typename PositionTraits::ElementType;
405 using CodecType = typename PositionArrayT::Codec;
406
407 using RandomGenerator = math::Rand01<ValueType, RandGenT>;
408
409 using TreeType = typename PointDataGridT::TreeType;
410
411 static_assert(PositionTraits::IsVec && PositionTraits::Size == 3,
412 "Invalid Position Array type.");
413
414 if (pointsPerVoxel < 0.0f) {
415 OPENVDB_THROW(ValueError, "Points per voxel must not be less than zero.");
416 }
417
418 if (spread < 0.0f || spread > 1.0f) {
419 OPENVDB_THROW(ValueError, "Spread must be between 0 and 1.");
420 }
421
422 if (interrupter) interrupter->start("Dense uniform scattering with fixed point count");
423
424 typename PointDataGridT::Ptr points =
425 point_scatter_internal::initialisePointTopology<PointDataGridT>(grid);
426 TreeType& tree = points->tree();
427 auto leafIter = tree.beginLeaf();
428 if (!leafIter) return points;
429
430 const Index32 pointsPerVoxelInt = math::Floor(pointsPerVoxel);
431 const double delta = pointsPerVoxel - float(pointsPerVoxelInt);
432 const bool fractional = !math::isApproxZero(delta, 1.0e-6);
433 const bool fractionalOnly = pointsPerVoxelInt == 0;
434
435 const AttributeSet::Descriptor::Ptr descriptor =
436 AttributeSet::Descriptor::create(PositionArrayT::attributeType());
437 RandomGenerator rand01(seed);
438
439 for (; leafIter; ++leafIter) {
440 if (util::wasInterrupted<InterrupterT>(interrupter)) break;
441 Index32 offset(0);
442 for (auto iter = leafIter->beginValueAll(); iter; ++iter) {
443 if (iter.isValueOn()) {
444 offset += pointsPerVoxelInt;
445 if (fractional && rand01() < delta) ++offset;
446 else if (fractionalOnly) leafIter->setValueOff(iter.pos());
447 }
448 // @note can't use iter.setValue(offset) on point grids
449 leafIter->setOffsetOnly(iter.pos(), offset);
450 }
451
452 if (offset != 0) {
453 point_scatter_internal::generatePositions<PositionType, CodecType>
454 (*leafIter, descriptor, offset, spread, rand01);
455 }
456 }
457
458 // if interrupted, remove remaining leaf nodes
459 const bool prune(leafIter || fractionalOnly);
460 for (; leafIter; ++leafIter) leafIter->setValuesOff();
461
462 if (prune) tools::pruneInactive(tree);
463 if (interrupter) interrupter->end();
464 return points;
465}
466
467
468////////////////////////////////////////
469
470
471template<
472 typename GridT,
473 typename RandGenT,
474 typename PositionArrayT,
475 typename PointDataGridT,
476 typename InterrupterT>
477inline typename PointDataGridT::Ptr
478nonUniformPointScatter(const GridT& grid,
479 const float pointsPerVoxel,
480 const unsigned int seed,
481 const float spread,
482 InterrupterT* interrupter)
483{
484 using PositionType = typename PositionArrayT::ValueType;
485 using PositionTraits = VecTraits<PositionType>;
486 using ValueType = typename PositionTraits::ElementType;
487 using CodecType = typename PositionArrayT::Codec;
488
489 using RandomGenerator = math::Rand01<ValueType, RandGenT>;
490
491 using TreeType = typename PointDataGridT::TreeType;
492
493 static_assert(PositionTraits::IsVec && PositionTraits::Size == 3,
494 "Invalid Position Array type.");
495 static_assert(std::is_arithmetic<typename GridT::ValueType>::value,
496 "Scalar grid type required for weighted voxel scattering.");
497
498 if (pointsPerVoxel < 0.0f) {
499 OPENVDB_THROW(ValueError, "Points per voxel must not be less than zero.");
500 }
501
502 if (spread < 0.0f || spread > 1.0f) {
503 OPENVDB_THROW(ValueError, "Spread must be between 0 and 1.");
504 }
505
506 if (interrupter) interrupter->start("Non-uniform scattering with local point density");
507
508 typename PointDataGridT::Ptr points =
509 point_scatter_internal::initialisePointTopology<PointDataGridT>(grid);
510 TreeType& tree = points->tree();
511 auto leafIter = tree.beginLeaf();
512 if (!leafIter) return points;
513
514 const AttributeSet::Descriptor::Ptr descriptor =
515 AttributeSet::Descriptor::create(PositionArrayT::attributeType());
516 RandomGenerator rand01(seed);
517 const auto accessor = grid.getConstAccessor();
518
519 for (; leafIter; ++leafIter) {
520 if (util::wasInterrupted<InterrupterT>(interrupter)) break;
521 Index32 offset(0);
522 for (auto iter = leafIter->beginValueAll(); iter; ++iter) {
523 if (iter.isValueOn()) {
524 double fractional =
525 double(accessor.getValue(iter.getCoord())) * pointsPerVoxel;
526 fractional = std::max(0.0, fractional);
527 int count = int(fractional);
528 if (rand01() < (fractional - double(count))) ++count;
529 else if (count == 0) leafIter->setValueOff(iter.pos());
530 offset += count;
531 }
532 // @note can't use iter.setValue(offset) on point grids
533 leafIter->setOffsetOnly(iter.pos(), offset);
534 }
535
536 if (offset != 0) {
537 point_scatter_internal::generatePositions<PositionType, CodecType>
538 (*leafIter, descriptor, offset, spread, rand01);
539 }
540 }
541
542 // if interrupted, remove remaining leaf nodes
543 for (; leafIter; ++leafIter) leafIter->setValuesOff();
544
545 tools::pruneInactive(points->tree());
546 if (interrupter) interrupter->end();
547 return points;
548}
549
550
551} // namespace points
552} // namespace OPENVDB_VERSION_NAME
553} // namespace openvdb
554
555
556#endif // OPENVDB_POINTS_POINT_SCATTER_HAS_BEEN_INCLUDED
AttributeArray.h
Attribute Array storage templated on type and compression codec.
value
ValueT value
Definition GridBuilder.h:1290
LeafManager.h
A LeafManager manages a linear array of pointers to a given tree's leaf nodes, as well as optional au...
NullInterrupter.h
PointCount.h
Methods for counting points in VDB Point grids.
PointDataGrid.h
Attribute-owned data structure for points. Point attributes are stored in leaf nodes and ordered by v...
Prune.h
Defined various multi-threaded utility functions for trees.
openvdb::v10_0::ValueError
Definition Exceptions.h:65
openvdb::v10_0::math::Rand01
Simple generator of random numbers over the range [0, 1)
Definition Math.h:167
openvdb::v10_0::math::RandInt
Simple random integer generator.
Definition Math.h:203
openvdb::v10_0::tree::LeafManager
This class manages a linear array of pointers to a given tree's leaf nodes, as well as optional auxil...
Definition LeafManager.h:85
openvdb::v10_0::tree::LeafManager::leafRange
LeafRange leafRange(size_t grainsize=1) const
Return a TBB-compatible LeafRange.
Definition LeafManager.h:345
openvdb::v10_0::points::denseUniformPointScatter
PointDataGridT::Ptr denseUniformPointScatter(const GridT &grid, const float pointsPerVoxel, const unsigned int seed=0, const float spread=1.0f, InterrupterT *interrupter=nullptr)
Uniformly scatter a fixed number of points per active voxel. If the pointsPerVoxel value provided is ...
Definition PointScatter.h:396
openvdb::v10_0::points::uniformPointScatter
PointDataGridT::Ptr uniformPointScatter(const GridT &grid, const Index64 count, const unsigned int seed=0, const float spread=1.0f, InterrupterT *interrupter=nullptr)
The free functions depend on the following class:
Definition PointScatter.h:224
openvdb::v10_0::points::nonUniformPointScatter
PointDataGridT::Ptr nonUniformPointScatter(const GridT &grid, const float pointsPerVoxel, const unsigned int seed=0, const float spread=1.0f, InterrupterT *interrupter=nullptr)
Non uniformly scatter points per active voxel. The pointsPerVoxel value is used to weight each grids ...
Definition PointScatter.h:478
openvdb::v10_0::Index
Index32 Index
Definition Types.h:54
openvdb::v10_0::Index32
uint32_t Index32
Definition Types.h:52
openvdb::v10_0::Index64
uint64_t Index64
Definition Types.h:53
openvdb_houdini::Grid
openvdb::GridBase Grid
Definition Utils.h:34
openvdb
Definition Exceptions.h:13
OPENVDB_THROW
#define OPENVDB_THROW(exception, message)
Definition Exceptions.h:74
Types.h
openvdb.h
openvdb::v10_0::VecTraits
Definition Types.h:205
OPENVDB_VERSION_NAME
#define OPENVDB_VERSION_NAME
The version namespace name for this library version.
Definition version.h.in:121
OPENVDB_USE_VERSION_NAMESPACE
#define OPENVDB_USE_VERSION_NAMESPACE
Definition version.h.in:212