OpenVDB: MapsUtil.h Source File

OpenVDB 5.1.0

MapsUtil.h
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1 //
3 // Copyright (c) 2012-2018 DreamWorks Animation LLC
4 //
5 // All rights reserved. This software is distributed under the
6 // Mozilla Public License 2.0 ( http://www.mozilla.org/MPL/2.0/ )
7 //
8 // Redistributions of source code must retain the above copyright
9 // and license notice and the following restrictions and disclaimer.
10 //
11 // * Neither the name of DreamWorks Animation nor the names of
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28 //
30 //
32
33 #ifndef OPENVDB_UTIL_MAPSUTIL_HAS_BEEN_INCLUDED
34 #define OPENVDB_UTIL_MAPSUTIL_HAS_BEEN_INCLUDED
35
36 #include <openvdb/math/Maps.h>
37 #include <algorithm> // for std::min(), std::max()
38 #include <cmath>
39 #include <vector>
40
41
42 namespace openvdb {
43 OPENVDB_USE_VERSION_NAMESPACE
44 namespace OPENVDB_VERSION_NAME {
45 namespace util {
46
47 // Utility methods for calculating bounding boxes
48
52 template<typename MapType>
53 inline void
54 calculateBounds(const MapType& map, const BBoxd& in, BBoxd& out)
55 {
56 const Vec3d& min = in.min();
57 const Vec3d& max = in.max();
58
59 // the pre-image of the 8 corners of the box
60 Vec3d corners[8];
61 corners[0] = in.min();;
62 corners[1] = Vec3d(min(0), min(1), min(2));
63 corners[2] = Vec3d(max(0), max(1), min(2));
64 corners[3] = Vec3d(min(0), max(1), min(2));
65 corners[4] = Vec3d(min(0), min(1), max(2));
66 corners[5] = Vec3d(max(0), min(1), max(2));
67 corners[6] = max;
68 corners[7] = Vec3d(min(0), max(1), max(2));
69
70 Vec3d pre_image;
71 Vec3d& out_min = out.min();
72 Vec3d& out_max = out.max();
73 out_min = map.applyInverseMap(corners[0]);
74 out_max = min;
75 for (int i = 1; i < 8; ++i) {
76 pre_image = map.applyInverseMap(corners[i]);
77 for (int j = 0; j < 3; ++j) {
78 out_min(j) = std::min( out_min(j), pre_image(j));
79 out_max(j) = std::max( out_max(j), pre_image(j));
80 }
81 }
82 }
83
84
87 template<typename MapType>
88 inline void
89 calculateBounds(const MapType& map, const Vec3d& center, const Real radius, BBoxd& out)
90 {
91 // On return, out gives a bounding box in continuous index space
92 // that encloses the sphere.
93 //
94 // the image of a sphere under the inverse of the linearMap will be an ellipsoid.
95
96 if (math::is_linear<MapType>::value) {
97 // I want to find extrema for three functions f(x', y', z') = x', or = y', or = z'
98 // with the constraint that g = (x-xo)^2 + (y-yo)^2 + (z-zo)^2 = r^2.
99 // Where the point x,y,z is the image of x',y',z'
100 // Solve: \lambda Grad(g) = Grad(f) and g = r^2.
101 // Note: here (x,y,z) is the image of (x',y',z'), and the gradient
102 // is w.r.t the (') space.
103 //
104 // This can be solved exactly: e_a^T (x' -xo') =\pm r\sqrt(e_a^T J^(-1)J^(-T)e_a)
105 // where e_a is one of the three unit vectors. - djh.
106
108 Vec3d center_pre_image = map.applyInverseMap(center);
109
110 std::vector<Vec3d> coordinate_units;
111 coordinate_units.push_back(Vec3d(1,0,0));
112 coordinate_units.push_back(Vec3d(0,1,0));
113 coordinate_units.push_back(Vec3d(0,0,1));
114
115 Vec3d& out_min = out.min();
116 Vec3d& out_max = out.max();
117 for (int direction = 0; direction < 3; ++direction) {
118 Vec3d temp = map.applyIJT(coordinate_units[direction]);
119 double offset =
120 radius * sqrt(temp.x()*temp.x() + temp.y()*temp.y() + temp.z()*temp.z());
121 out_min(direction) = center_pre_image(direction) - offset;
122 out_max(direction) = center_pre_image(direction) + offset;
123 }
124
125 } else {
126 // This is some unknown map type. In this case, we form an axis-aligned
127 // bounding box for the sphere in world space and find the pre-images of
128 // the corners in index space. From these corners we compute an axis-aligned
129 // bounding box in index space.
130 BBoxd bounding_box(center - radius*Vec3d(1,1,1), center + radius*Vec3d(1,1,1));
131 calculateBounds<MapType>(map, bounding_box, out);
132 }
133 }
134
135
136 namespace { // anonymous namespace for this helper function
137
144 inline int
145 findTangentPoints(const double g, const double xo, const double zo,
146 const double r, double& xp, double& zp, double& xm, double& zm)
147 {
148 double x2 = xo * xo;
149 double r2 = r * r;
150 double xd = g * xo;
151 double xd2 = xd*xd;
152 double zd = g * zo + 1.;
153 double zd2 = zd*zd;
154 double rd2 = r2*g*g;
155
156 double distA = xd2 + zd2;
157 double distB = distA - rd2;
158
159 if (distB > 0) {
160 double discriminate = sqrt(distB);
161
162 xp = xo - xo*rd2/distA + r * zd *discriminate / distA;
163 xm = xo - xo*rd2/distA - r * zd *discriminate / distA;
164
165 zp = (zo*zd2 + zd*g*(x2 - r2) - xo*xo*g - r*xd*discriminate) / distA;
166 zm = (zo*zd2 + zd*g*(x2 - r2) - xo*xo*g + r*xd*discriminate) / distA;
167
168 return 2;
169
170 } if (0 >= distB && distB >= -1e-9) {
171 // the circle touches the focal point (x=0, z = -1/g)
172 xp = 0; xm = 0;
173 zp = -1/g; zm = -1/g;
174
175 return 1;
176 }
177
178 return 0;
179 }
180
181 } // end anonymous namespace
182
183
187 template<>
188 inline void
189 calculateBounds<math::NonlinearFrustumMap>(const math::NonlinearFrustumMap& frustum,
190 const Vec3d& center, const Real radius, BBoxd& out)
191 {
192 // The frustum is a nonlinear map followed by a uniform scale, rotation, translation.
193 // First we invert the translation, rotation and scale to find the spherical pre-image
194 // of the sphere in "local" coordinates where the frustum is aligned with the near plane
195 // on the z=0 plane and the "camera" is located at (x=0, y=0, z=-1/g).
196
197 // check that the internal map has no shear.
198 const math::AffineMap& secondMap = frustum.secondMap();
199 // test if the linear part has shear or non-uniform scaling
200 if (!frustum.hasSimpleAffine()) {
201
202 // In this case, we form an axis-aligned bounding box for sphere in world space
203 // and find the pre_images of the corners in voxel space. From these corners we
204 // compute an axis-algined bounding box in voxel-spae
205 BBoxd bounding_box(center - radius*Vec3d(1,1,1), center + radius*Vec3d(1,1,1));
206 calculateBounds<math::NonlinearFrustumMap>(frustum, bounding_box, out);
207 return;
208 }
209
210 // for convenience
211 Vec3d& out_min = out.min();
212 Vec3d& out_max = out.max();
213
214 Vec3d centerLS = secondMap.applyInverseMap(center);
215 Vec3d voxelSize = secondMap.voxelSize();
216
217 // all the voxels have the same size since we know this is a simple affine map
218 double radiusLS = radius / voxelSize(0);
219
220 double gamma = frustum.getGamma();
221 double xp;
222 double zp;
223 double xm;
224 double zm;
225 int soln_number;
226
227 // the bounding box in index space for the points in the frustum
228 const BBoxd& bbox = frustum.getBBox();
229 // initialize min and max
230 const double x_min = bbox.min().x();
231 const double y_min = bbox.min().y();
232 const double z_min = bbox.min().z();
233
234 const double x_max = bbox.max().x();
235 const double y_max = bbox.max().y();
236 const double z_max = bbox.max().z();
237
238 out_min.x() = x_min;
239 out_max.x() = x_max;
240 out_min.y() = y_min;
241 out_max.y() = y_max;
242
243 Vec3d extreme;
244 Vec3d extreme2;
245 Vec3d pre_image;
246 // find the x-range
247 soln_number = findTangentPoints(gamma, centerLS.x(), centerLS.z(), radiusLS, xp, zp, xm, zm);
248 if (soln_number == 2) {
249 extreme.x() = xp;
250 extreme.y() = centerLS.y();
251 extreme.z() = zp;
252
253 // location in world space of the tangent point
254 extreme2 = secondMap.applyMap(extreme);
255 // convert back to voxel space
256 pre_image = frustum.applyInverseMap(extreme2);
257 out_max.x() = std::max(x_min, std::min(x_max, pre_image.x()));
258
259 extreme.x() = xm;
260 extreme.y() = centerLS.y();
261 extreme.z() = zm;
262 // location in world space of the tangent point
263 extreme2 = secondMap.applyMap(extreme);
264
265 // convert back to voxel space
266 pre_image = frustum.applyInverseMap(extreme2);
267 out_min.x() = std::max(x_min, std::min(x_max, pre_image.x()));
268
269 } else if (soln_number == 1) {
270 // the circle was tangent at the focal point
271 } else if (soln_number == 0) {
272 // the focal point was inside the circle
273 }
274
275 // find the y-range
276 soln_number = findTangentPoints(gamma, centerLS.y(), centerLS.z(), radiusLS, xp, zp, xm, zm);
277 if (soln_number == 2) {
278 extreme.x() = centerLS.x();
279 extreme.y() = xp;
280 extreme.z() = zp;
281
282 // location in world space of the tangent point
283 extreme2 = secondMap.applyMap(extreme);
284 // convert back to voxel space
285 pre_image = frustum.applyInverseMap(extreme2);
286 out_max.y() = std::max(y_min, std::min(y_max, pre_image.y()));
287
288 extreme.x() = centerLS.x();
289 extreme.y() = xm;
290 extreme.z() = zm;
291 extreme2 = secondMap.applyMap(extreme);
292
293 // convert back to voxel space
294 pre_image = frustum.applyInverseMap(extreme2);
295 out_min.y() = std::max(y_min, std::min(y_max, pre_image.y()));
296
297 } else if (soln_number == 1) {
298 // the circle was tangent at the focal point
299 } else if (soln_number == 0) {
300 // the focal point was inside the circle
301 }
302
303 // the near and far
304 // the closest point. The front of the frustum is at 0 in index space
305 double near_dist = std::max(centerLS.z() - radiusLS, 0.);
306 // the farthest point. The back of the frustum is at mDepth in index space
307 double far_dist = std::min(centerLS.z() + radiusLS, frustum.getDepth() );
308
309 Vec3d near_point(0.f, 0.f, near_dist);
310 Vec3d far_point(0.f, 0.f, far_dist);
311
312 out_min.z() = std::max(z_min, frustum.applyInverseMap(secondMap.applyMap(near_point)).z());
313 out_max.z() = std::min(z_max, frustum.applyInverseMap(secondMap.applyMap(far_point)).z());
314
315 }
316
317 } // namespace util
318 } // namespace OPENVDB_VERSION_NAME
319 } // namespace openvdb
320
321 #endif // OPENVDB_UTIL_MAPSUTIL_HAS_BEEN_INCLUDED
322
323 // Copyright (c) 2012-2018 DreamWorks Animation LLC
324 // All rights reserved. This software is distributed under the
325 // Mozilla Public License 2.0 ( http://www.mozilla.org/MPL/2.0/ )
openvdb::v5_1::math::BBox::min
const Vec3T & min() const
Return a const reference to the minimum point of this bounding box.
Definition: BBox.h:89
openvdb::v5_1::Real
double Real
Definition: Types.h:67
Maps.h
openvdb::v5_1::math::AffineMap::applyInverseMap
Vec3d applyInverseMap(const Vec3d &in) const override
Return the pre-image of in under the map.
Definition: Maps.h:445
OPENVDB_VERSION_NAME
#define OPENVDB_VERSION_NAME
The version namespace name for this library version.
Definition: version.h:136
openvdb::v5_1::util::calculateBounds
void calculateBounds(const MapType &map, const Vec3d &center, const Real radius, BBoxd &out)
Calculate an axis-aligned bounding box in the given map&#39;s domain from a spherical bounding box in its...
Definition: MapsUtil.h:89
openvdb::v5_1::math::Vec3d
Vec3< double > Vec3d
Definition: Vec3.h:679
openvdb::v5_1::math::Vec3::x
T & x()
Reference to the component, e.g. v.x() = 4.5f;.
Definition: Vec3.h:110
openvdb
Definition: Exceptions.h:40
openvdb::v5_1::math::is_linear
Map traits.
Definition: Maps.h:82
openvdb::v5_1::math::NonlinearFrustumMap
This map is composed of three steps. First it will take a box of size (Lx X Ly X Lz) defined by a mem...
Definition: Maps.h:1905
openvdb::v5_1::math::AffineMap::applyMap
Vec3d applyMap(const Vec3d &in) const override
Return the image of in under the map.
Definition: Maps.h:443
openvdb::v5_1::math::BBox::max
const Vec3T & max() const
Return a const reference to the maximum point of this bounding box.
Definition: BBox.h:91
openvdb::v5_1::tools::composite::min
const std::enable_if<!VecTraits< T >::IsVec, T >::type & min(const T &a, const T &b)
Definition: Composite.h:129
openvdb::v5_1::math::AffineMap
A general linear transform using homogeneous coordinates to perform rotation, scaling, shear and translation.
Definition: Maps.h:327
OPENVDB_USE_VERSION_NAMESPACE
#define OPENVDB_USE_VERSION_NAMESPACE
Definition: version.h:188
openvdb::v5_1::tools::composite::max
const std::enable_if<!VecTraits< T >::IsVec, T >::type & max(const T &a, const T &b)
Definition: Composite.h:133
openvdb::v5_1::math::AffineMap::voxelSize
Vec3d voxelSize() const override
Return the lengths of the images of the segments (0,0,0)-(1,0,0), (0,0,0)-(0,1,0) and (0...
Definition: Maps.h:493
openvdb::v5_1::math::BBox< Vec3d >
openvdb::v5_1::math::Vec3::z
T & z()
Definition: Vec3.h:112
openvdb::v5_1::math::Vec3::y
T & y()
Definition: Vec3.h:111