OpenVDB 12.1.0

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DDA.h
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1// Copyright Contributors to the OpenVDB Project
2// SPDX-License-Identifier: Apache-2.0
3//
4/// @file DDA.h
5///
6/// @author Ken Museth
7///
8/// @brief Digital Differential Analyzers specialized for VDB.
9
10#ifndef OPENVDB_MATH_DDA_HAS_BEEN_INCLUDED
11#define OPENVDB_MATH_DDA_HAS_BEEN_INCLUDED
12
13#include "Coord.h"
14#include "Math.h"
15#include "Vec3.h"
16#include <openvdb/Types.h>
17#include <openvdb/util/Assert.h>
18#include <iostream> // for std::ostream
19#include <limits> // for std::numeric_limits<Type>::max()
20
21 namespace openvdb {
22 OPENVDB_USE_VERSION_NAMESPACE
23 namespace OPENVDB_VERSION_NAME {
24 namespace math {
25
26/// @brief A Digital Differential Analyzer specialized for OpenVDB grids
27/// @note Conceptually similar to Bresenham's line algorithm applied
28/// to a 3D Ray intersecting OpenVDB nodes or voxels. Log2Dim = 0
29/// corresponds to a voxel and Log2Dim a tree node of size 2^Log2Dim.
30///
31/// @note The Ray template class is expected to have the following
32/// methods: test(time), t0(), t1(), invDir(), and operator()(time).
33/// See the example Ray class above for their definition.
34 template<typename RayT, Index Log2Dim = 0>
35 class DDA
36{
37 public:
38 using RealType = typename RayT::RealType;
39 using RealT = RealType;
40 using Vec3Type = typename RayT::Vec3Type;
41 using Vec3T = Vec3Type;
42
43 /// @brief uninitialized constructor
44 DDA() {}
45
46 DDA(const RayT& ray) { this->init(ray); }
47
48 DDA(const RayT& ray, RealT startTime) { this->init(ray, startTime); }
49
50 DDA(const RayT& ray, RealT startTime, RealT maxTime) { this->init(ray, startTime, maxTime); }
51
52 inline void init(const RayT& ray, RealT startTime, RealT maxTime)
53 {
54 OPENVDB_ASSERT(startTime <= maxTime);
55 static const int DIM = 1 << Log2Dim;
56 mT0 = startTime;
57 mT1 = maxTime;
58 const Vec3T &pos = ray(mT0), &dir = ray.dir(), &inv = ray.invDir();
59 mVoxel = Coord::floor(pos) & (~(DIM-1));
60 for (int axis = 0; axis < 3; ++axis) {
61 if (math::isZero(dir[axis])) {//handles dir = +/- 0
62 mStep[axis] = 0;//dummy value
63 mNext[axis] = std::numeric_limits<RealT>::max();//i.e. disabled!
64 mDelta[axis] = std::numeric_limits<RealT>::max();//dummy value
65 } else if (inv[axis] > 0) {
66 mStep[axis] = DIM;
67 mNext[axis] = mT0 + (mVoxel[axis] + DIM - pos[axis]) * inv[axis];
68 mDelta[axis] = mStep[axis] * inv[axis];
69 } else {
70 mStep[axis] = -DIM;
71 mNext[axis] = mT0 + (mVoxel[axis] - pos[axis]) * inv[axis];
72 mDelta[axis] = mStep[axis] * inv[axis];
73 }
74 }
75 }
76
77 inline void init(const RayT& ray) { this->init(ray, ray.t0(), ray.t1()); }
78
79 inline void init(const RayT& ray, RealT startTime) { this->init(ray, startTime, ray.t1()); }
80
81 /// @brief Increment the voxel index to next intersected voxel or node
82 /// and returns true if the step in time does not exceed maxTime.
83 inline bool step()
84 {
85 const int stepAxis = static_cast<int>(math::MinIndex(mNext));
86 mT0 = mNext[stepAxis];
87 mNext[stepAxis] += mDelta[stepAxis];
88 mVoxel[stepAxis] += mStep[stepAxis];
89 return mT0 <= mT1;
90 }
91
92 /// @brief Return the index coordinates of the next node or voxel
93 /// intersected by the ray. If Log2Dim = 0 the return value is the
94 /// actual signed coordinate of the voxel, else it is the origin
95 /// of the corresponding VDB tree node or tile.
96 /// @note Incurs no computational overhead.
97 inline const Coord& voxel() const { return mVoxel; }
98
99 /// @brief Return the time (parameterized along the Ray) of the
100 /// first hit of a tree node of size 2^Log2Dim.
101 /// @details This value is initialized to startTime or ray.t0()
102 /// depending on the constructor used.
103 /// @note Incurs no computational overhead.
104 inline RealType time() const { return mT0; }
105
106 /// @brief Return the maximum time (parameterized along the Ray).
107 inline RealType maxTime() const { return mT1; }
108
109 /// @brief Return the time (parameterized along the Ray) of the
110 /// second (i.e. next) hit of a tree node of size 2^Log2Dim.
111 /// @note Incurs a (small) computational overhead.
112 inline RealType next() const { return math::Min(mT1, mNext[0], mNext[1], mNext[2]); }
113
114 /// @brief Print information about this DDA for debugging.
115 /// @param os a stream to which to write textual information.
116 void print(std::ostream& os = std::cout) const
117 {
118 os << "Dim=" << (1<<Log2Dim) << " time=" << mT0 << " next()="
119 << this->next() << " voxel=" << mVoxel << " next=" << mNext
120 << " delta=" << mDelta << " step=" << mStep << std::endl;
121 }
122
123 private:
124 RealT mT0, mT1;
125 Coord mVoxel, mStep;
126 Vec3T mDelta, mNext;
127}; // class DDA
128
129/// @brief Output streaming of the Ray class.
130/// @note Primarily intended for debugging.
131 template<typename RayT, Index Log2Dim>
132 inline std::ostream& operator<<(std::ostream& os, const DDA<RayT, Log2Dim>& dda)
133{
134 os << "Dim=" << (1<<Log2Dim) << " time=" << dda.time()
135 << " next()=" << dda.next() << " voxel=" << dda.voxel();
136 return os;
137}
138
139/////////////////////////////////////////// LevelSetHDDA ////////////////////////////////////////////
140
141
142/// @brief Helper class that implements Hierarchical Digital Differential Analyzers
143/// and is specialized for ray intersections with level sets
144 template<typename TreeT, int NodeLevel>
145 struct LevelSetHDDA
146{
147 using ChainT = typename TreeT::RootNodeType::NodeChainType;
148 using NodeT = typename ChainT::template Get<NodeLevel>;
149
150 template <typename TesterT>
151 static bool test(TesterT& tester)
152 {
153 math::DDA<typename TesterT::RayT, NodeT::TOTAL> dda(tester.ray());
154 do {
155 if (tester.template hasNode<NodeT>(dda.voxel())) {
156 tester.setRange(dda.time(), dda.next());
157 if (LevelSetHDDA<TreeT, NodeLevel-1>::test(tester)) return true;
158 }
159 } while(dda.step());
160 return false;
161 }
162};
163
164/// @brief Specialization of Hierarchical Digital Differential Analyzer
165/// class that intersects a ray against the voxels of a level set
166 template<typename TreeT>
167 struct LevelSetHDDA<TreeT, -1>
168{
169 template <typename TesterT>
170 static bool test(TesterT& tester)
171 {
172 math::DDA<typename TesterT::RayT, 0> dda(tester.ray());
173 tester.init(dda.time());
174 do { if (tester(dda.voxel(), dda.next())) return true; } while(dda.step());
175 return false;
176 }
177};
178
179//////////////////////////////////////////// VolumeHDDA /////////////////////////////////////////////
180
181/// @brief Helper class that implements Hierarchical Digital Differential Analyzers
182/// for ray intersections against a generic volume.
183///
184/// @details The template argument ChildNodeLevel specifies the entry
185/// upper node level used for the hierarchical ray-marching. The final
186/// lowest level is always the leaf node level, i.e. not the voxel level!
187 template <typename TreeT, typename RayT, int ChildNodeLevel>
188 class VolumeHDDA
189{
190 public:
191
192 using ChainT = typename TreeT::RootNodeType::NodeChainType;
193 using NodeT = typename ChainT::template Get<ChildNodeLevel>;
194 using TimeSpanT = typename RayT::TimeSpan;
195
196 VolumeHDDA() {}
197
198 template <typename AccessorT>
199 TimeSpanT march(RayT& ray, AccessorT &acc)
200 {
201 TimeSpanT t(-1, -1);
202 if (ray.valid()) this->march(ray, acc, t);
203 return t;
204 }
205
206 /// ListType is a list of RayType::TimeSpan and is required to
207 /// have the two methods: clear() and push_back(). Thus, it could
208 /// be std::vector<typename RayType::TimeSpan> or
209 /// std::deque<typename RayType::TimeSpan>.
210 template <typename AccessorT, typename ListT>
211 void hits(RayT& ray, AccessorT &acc, ListT& times)
212 {
213 TimeSpanT t(-1,-1);
214 times.clear();
215 this->hits(ray, acc, times, t);
216 if (t.valid()) times.push_back(t);
217 }
218
219 private:
220
221 friend class VolumeHDDA<TreeT, RayT, ChildNodeLevel+1>;
222
223 template <typename AccessorT>
224 bool march(RayT& ray, AccessorT &acc, TimeSpanT& t)
225 {
226 mDDA.init(ray);
227 do {
228 if (acc.template probeConstNode<NodeT>(mDDA.voxel()) != nullptr) {//child node
229 ray.setTimes(mDDA.time(), mDDA.next());
230 if (mHDDA.march(ray, acc, t)) return true;//terminate
231 } else if (acc.isValueOn(mDDA.voxel())) {//hit an active tile
232 if (t.t0<0) t.t0 = mDDA.time();//this is the first hit so set t0
233 } else if (t.t0>=0) {//hit an inactive tile after hitting active values
234 t.t1 = mDDA.time();//set end of active ray segment
235 if (t.valid()) return true;//terminate
236 t.set(-1, -1);//reset to an empty and invalid time-span
237 }
238 } while (mDDA.step());
239 if (t.t0>=0) t.t1 = mDDA.maxTime();
240 return false;
241 }
242
243 /// ListType is a list of RayType::TimeSpan and is required to
244 /// have the two methods: clear() and push_back(). Thus, it could
245 /// be std::vector<typename RayType::TimeSpan> or
246 /// std::deque<typename RayType::TimeSpan>.
247 template <typename AccessorT, typename ListT>
248 void hits(RayT& ray, AccessorT &acc, ListT& times, TimeSpanT& t)
249 {
250 mDDA.init(ray);
251 do {
252 if (acc.template probeConstNode<NodeT>(mDDA.voxel()) != nullptr) {//child node
253 ray.setTimes(mDDA.time(), mDDA.next());
254 mHDDA.hits(ray, acc, times, t);
255 } else if (acc.isValueOn(mDDA.voxel())) {//hit an active tile
256 if (t.t0<0) t.t0 = mDDA.time();//this is the first hit so set t0
257 } else if (t.t0>=0) {//hit an inactive tile after hitting active values
258 t.t1 = mDDA.time();//set end of active ray segment
259 if (t.valid()) times.push_back(t);
260 t.set(-1,-1);//reset to an empty and invalid time-span
261 }
262 } while (mDDA.step());
263 if (t.t0>=0) t.t1 = mDDA.maxTime();
264 }
265
266 math::DDA<RayT, NodeT::TOTAL> mDDA;
267 VolumeHDDA<TreeT, RayT, ChildNodeLevel-1> mHDDA;
268};
269
270/// @brief Specialization of Hierarchical Digital Differential Analyzer
271/// class that intersects against the leafs or tiles of a generic volume.
272 template <typename TreeT, typename RayT>
273 class VolumeHDDA<TreeT, RayT, 0>
274{
275 public:
276
277 using LeafT = typename TreeT::LeafNodeType;
278 using TimeSpanT = typename RayT::TimeSpan;
279
280 VolumeHDDA() {}
281
282 template <typename AccessorT>
283 TimeSpanT march(RayT& ray, AccessorT &acc)
284 {
285 TimeSpanT t(-1, -1);
286 if (ray.valid()) this->march(ray, acc, t);
287 return t;
288 }
289
290 template <typename AccessorT, typename ListT>
291 void hits(RayT& ray, AccessorT &acc, ListT& times)
292 {
293 TimeSpanT t(-1,-1);
294 times.clear();
295 this->hits(ray, acc, times, t);
296 if (t.valid()) times.push_back(t);
297 }
298
299 private:
300
301 friend class VolumeHDDA<TreeT, RayT, 1>;
302
303 template <typename AccessorT>
304 bool march(RayT& ray, AccessorT &acc, TimeSpanT& t)
305 {
306 mDDA.init(ray);
307 do {
308 if (acc.template probeConstNode<LeafT>(mDDA.voxel()) ||
309 acc.isValueOn(mDDA.voxel())) {//hit a leaf or an active tile
310 if (t.t0<0) t.t0 = mDDA.time();//this is the first hit
311 } else if (t.t0>=0) {//hit an inactive tile after hitting active values
312 t.t1 = mDDA.time();//set end of active ray segment
313 if (t.valid()) return true;//terminate
314 t.set(-1, -1);//reset to an empty and invalid time-span
315 }
316 } while (mDDA.step());
317 if (t.t0>=0) t.t1 = mDDA.maxTime();
318 return false;
319 }
320
321 template <typename AccessorT, typename ListT>
322 void hits(RayT& ray, AccessorT &acc, ListT& times, TimeSpanT& t)
323 {
324 mDDA.init(ray);
325 do {
326 if (acc.template probeConstNode<LeafT>(mDDA.voxel()) ||
327 acc.isValueOn(mDDA.voxel())) {//hit a leaf or an active tile
328 if (t.t0<0) t.t0 = mDDA.time();//this is the first hit
329 } else if (t.t0>=0) {//hit an inactive tile after hitting active values
330 t.t1 = mDDA.time();//set end of active ray segment
331 if (t.valid()) times.push_back(t);
332 t.set(-1, -1);//reset to an empty and invalid time-span
333 }
334 } while (mDDA.step());
335 if (t.t0>=0) t.t1 = mDDA.maxTime();
336 }
337 math::DDA<RayT, LeafT::TOTAL> mDDA;
338};
339
340} // namespace math
341} // namespace OPENVDB_VERSION_NAME
342} // namespace openvdb
343
344#endif // OPENVDB_MATH_DDA_HAS_BEEN_INCLUDED
Assert.h
OPENVDB_ASSERT
#define OPENVDB_ASSERT(X)
Definition Assert.h:41
Coord.h
operator<<
OPENVDB_API std::ostream & operator<<(std::ostream &os, half h)
Output h to os, formatted as a float.
Math.h
General-purpose arithmetic and comparison routines, most of which accept arbitrary value types (or at...
Vec3.h
openvdb::v12_1::math::Coord
Signed (x, y, z) 32-bit integer coordinates.
Definition Coord.h:26
openvdb::v12_1::math::Coord::floor
static Coord floor(const Vec3< T > &xyz)
Return the largest integer coordinates that are not greater than xyz (node centered conversion).
Definition Coord.h:57
openvdb::v12_1::math::DDA
A Digital Differential Analyzer specialized for OpenVDB grids.
Definition DDA.h:36
openvdb::v12_1::math::DDA::step
bool step()
Increment the voxel index to next intersected voxel or node and returns true if the step in time does...
Definition DDA.h:83
openvdb::v12_1::math::DDA::voxel
const Coord & voxel() const
Return the index coordinates of the next node or voxel intersected by the ray. If Log2Dim = 0 the ret...
Definition DDA.h:97
openvdb::v12_1::math::DDA::DDA
DDA(const RayT &ray)
Definition DDA.h:46
openvdb::v12_1::math::DDA::DDA
DDA(const RayT &ray, RealT startTime)
Definition DDA.h:48
openvdb::v12_1::math::DDA::DDA
DDA(const RayT &ray, RealT startTime, RealT maxTime)
Definition DDA.h:50
openvdb::v12_1::math::DDA::RealT
RealType RealT
Definition DDA.h:39
openvdb::v12_1::math::DDA::next
RealType next() const
Return the time (parameterized along the Ray) of the second (i.e. next) hit of a tree node of size 2^...
Definition DDA.h:112
openvdb::v12_1::math::DDA::maxTime
RealType maxTime() const
Return the maximum time (parameterized along the Ray).
Definition DDA.h:107
openvdb::v12_1::math::DDA::init
void init(const RayT &ray)
Definition DDA.h:77
openvdb::v12_1::math::DDA::init
void init(const RayT &ray, RealT startTime)
Definition DDA.h:79
openvdb::v12_1::math::DDA::Vec3T
Vec3Type Vec3T
Definition DDA.h:41
openvdb::v12_1::math::DDA::init
void init(const RayT &ray, RealT startTime, RealT maxTime)
Definition DDA.h:52
openvdb::v12_1::math::DDA::DDA
DDA()
uninitialized constructor
Definition DDA.h:44
openvdb::v12_1::math::DDA::Vec3Type
typename RayT::Vec3Type Vec3Type
Definition DDA.h:40
openvdb::v12_1::math::DDA::RealType
typename RayT::RealType RealType
Definition DDA.h:38
openvdb::v12_1::math::DDA::print
void print(std::ostream &os=std::cout) const
Print information about this DDA for debugging.
Definition DDA.h:116
openvdb::v12_1::math::DDA::time
RealType time() const
Return the time (parameterized along the Ray) of the first hit of a tree node of size 2^Log2Dim.
Definition DDA.h:104
openvdb::v12_1::math::VolumeHDDA< TreeT, RayT, 0 >::TimeSpanT
typename RayT::TimeSpan TimeSpanT
Definition DDA.h:278
openvdb::v12_1::math::VolumeHDDA< TreeT, RayT, 0 >::LeafT
typename TreeT::LeafNodeType LeafT
Definition DDA.h:277
openvdb::v12_1::math::VolumeHDDA< TreeT, RayT, 0 >::VolumeHDDA
VolumeHDDA()
Definition DDA.h:280
openvdb::v12_1::math::VolumeHDDA< TreeT, RayT, 0 >::march
TimeSpanT march(RayT &ray, AccessorT &acc)
Definition DDA.h:283
openvdb::v12_1::math::VolumeHDDA< TreeT, RayT, 0 >::hits
void hits(RayT &ray, AccessorT &acc, ListT &times)
Definition DDA.h:291
openvdb::v12_1::math::VolumeHDDA
Helper class that implements Hierarchical Digital Differential Analyzers for ray intersections agains...
Definition DDA.h:189
openvdb::v12_1::math::VolumeHDDA::TimeSpanT
typename RayT::TimeSpan TimeSpanT
Definition DDA.h:194
openvdb::v12_1::math::VolumeHDDA::VolumeHDDA
VolumeHDDA()
Definition DDA.h:196
openvdb::v12_1::math::VolumeHDDA::march
TimeSpanT march(RayT &ray, AccessorT &acc)
Definition DDA.h:199
openvdb::v12_1::math::VolumeHDDA::NodeT
typename ChainT::template Get< ChildNodeLevel > NodeT
Definition DDA.h:193
openvdb::v12_1::math::VolumeHDDA::hits
void hits(RayT &ray, AccessorT &acc, ListT &times)
Definition DDA.h:211
openvdb::v12_1::math::VolumeHDDA::ChainT
typename TreeT::RootNodeType::NodeChainType ChainT
Definition DDA.h:192
openvdb::v12_1::math::MinIndex
size_t MinIndex(const Vec3T &v)
Return the index [0,1,2] of the smallest value in a 3D vector.
Definition Math.h:930
openvdb::v12_1::math::Min
const Type & Min(const Type &a, const Type &b)
Return the minimum of two values.
Definition Math.h:656
openvdb::v12_1::math::isZero
bool isZero(const Type &x)
Return true if x is exactly equal to zero.
Definition Math.h:337
openvdb
Definition Exceptions.h:13
Types.h
openvdb::v12_1::math::LevelSetHDDA< TreeT, -1 >::test
static bool test(TesterT &tester)
Definition DDA.h:170
openvdb::v12_1::math::LevelSetHDDA
Helper class that implements Hierarchical Digital Differential Analyzers and is specialized for ray i...
Definition DDA.h:146
openvdb::v12_1::math::LevelSetHDDA::NodeT
typename ChainT::template Get< NodeLevel > NodeT
Definition DDA.h:148
openvdb::v12_1::math::LevelSetHDDA::test
static bool test(TesterT &tester)
Definition DDA.h:151
openvdb::v12_1::math::LevelSetHDDA::ChainT
typename TreeT::RootNodeType::NodeChainType ChainT
Definition DDA.h:147
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:218