Bullet Collision Detection & Physics Library
btSparseSDF.h
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1/*
2Bullet Continuous Collision Detection and Physics Library
3Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
4
5This software is provided 'as-is', without any express or implied warranty.
6In no event will the authors be held liable for any damages arising from the use of this software.
7Permission is granted to anyone to use this software for any purpose,
8including commercial applications, and to alter it and redistribute it freely,
9subject to the following restrictions:
10
111. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
122. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
133. This notice may not be removed or altered from any source distribution.
14*/
16
17#ifndef BT_SPARSE_SDF_H
18#define BT_SPARSE_SDF_H
19
22
23// Modified Paul Hsieh hash
24template <const int DWORDLEN>
25unsigned int HsiehHash(const void* pdata)
26{
27 const unsigned short* data=(const unsigned short*)pdata;
28 unsigned hash=DWORDLEN<<2,tmp;
29 for(int i=0;i<DWORDLEN;++i)
30 {
31 hash += data[0];
32 tmp = (data[1]<<11)^hash;
33 hash = (hash<<16)^tmp;
34 data += 2;
35 hash += hash>>11;
36 }
37 hash^=hash<<3;hash+=hash>>5;
38 hash^=hash<<4;hash+=hash>>17;
39 hash^=hash<<25;hash+=hash>>6;
40 return(hash);
41}
42
43template <const int CELLSIZE>
45{
46 //
47 // Inner types
48 //
49 struct IntFrac
50 {
51 int b;
52 int i;
54 };
55 struct Cell
56 {
57 btScalar d[CELLSIZE+1][CELLSIZE+1][CELLSIZE+1];
58 int c[3];
59 int puid;
60 unsigned hash;
63 };
64 //
65 // Fields
66 //
67
70 int puid;
71 int ncells;
75
76 //
77 // Methods
78 //
79
80 //
81 void Initialize(int hashsize=2383, int clampCells = 256*1024)
82 {
83 //avoid a crash due to running out of memory, so clamp the maximum number of cells allocated
84 //if this limit is reached, the SDF is reset (at the cost of some performance during the reset)
85 m_clampCells = clampCells;
86 cells.resize(hashsize,0);
87 Reset();
88 }
89 //
90 void Reset()
91 {
92 for(int i=0,ni=cells.size();i<ni;++i)
93 {
94 Cell* pc=cells[i];
95 cells[i]=0;
96 while(pc)
97 {
98 Cell* pn=pc->next;
99 delete pc;
100 pc=pn;
101 }
102 }
103 voxelsz =0.25;
104 puid =0;
105 ncells =0;
106 nprobes =1;
107 nqueries =1;
108 }
109 //
110 void GarbageCollect(int lifetime=256)
111 {
112 const int life=puid-lifetime;
113 for(int i=0;i<cells.size();++i)
114 {
115 Cell*& root=cells[i];
116 Cell* pp=0;
117 Cell* pc=root;
118 while(pc)
119 {
120 Cell* pn=pc->next;
121 if(pc->puid<life)
122 {
123 if(pp) pp->next=pn; else root=pn;
124 delete pc;pc=pp;--ncells;
125 }
126 pp=pc;pc=pn;
127 }
128 }
129 //printf("GC[%d]: %d cells, PpQ: %f\r\n",puid,ncells,nprobes/(btScalar)nqueries);
130 nqueries=1;
131 nprobes=1;
132 ++puid;
133 /* else setup a priority list... */
134 }
135 //
137 {
138 int refcount=0;
139 for(int i=0;i<cells.size();++i)
140 {
141 Cell*& root=cells[i];
142 Cell* pp=0;
143 Cell* pc=root;
144 while(pc)
145 {
146 Cell* pn=pc->next;
147 if(pc->pclient==pcs)
148 {
149 if(pp) pp->next=pn; else root=pn;
150 delete pc;pc=pp;++refcount;
151 }
152 pp=pc;pc=pn;
153 }
154 }
155 return(refcount);
156 }
157 //
159 const btCollisionShape* shape,
160 btVector3& normal,
161 btScalar margin)
162 {
163 /* Lookup cell */
164 const btVector3 scx=x/voxelsz;
165 const IntFrac ix=Decompose(scx.x());
166 const IntFrac iy=Decompose(scx.y());
167 const IntFrac iz=Decompose(scx.z());
168 const unsigned h=Hash(ix.b,iy.b,iz.b,shape);
169 Cell*& root=cells[static_cast<int>(h%cells.size())];
170 Cell* c=root;
171 ++nqueries;
172 while(c)
173 {
174 ++nprobes;
175 if( (c->hash==h) &&
176 (c->c[0]==ix.b) &&
177 (c->c[1]==iy.b) &&
178 (c->c[2]==iz.b) &&
179 (c->pclient==shape))
180 { break; }
181 else
182 { c=c->next; }
183 }
184 if(!c)
185 {
186 ++nprobes;
187 ++ncells;
188 //int sz = sizeof(Cell);
190 {
191 static int numResets=0;
192 numResets++;
193// printf("numResets=%d\n",numResets);
194 Reset();
195 }
196
197 c=new Cell();
198 c->next=root;root=c;
199 c->pclient=shape;
200 c->hash=h;
201 c->c[0]=ix.b;c->c[1]=iy.b;c->c[2]=iz.b;
202 BuildCell(*c);
203 }
204 c->puid=puid;
205 /* Extract infos */
206 const int o[]={ ix.i,iy.i,iz.i};
207 const btScalar d[]={ c->d[o[0]+0][o[1]+0][o[2]+0],
208 c->d[o[0]+1][o[1]+0][o[2]+0],
209 c->d[o[0]+1][o[1]+1][o[2]+0],
210 c->d[o[0]+0][o[1]+1][o[2]+0],
211 c->d[o[0]+0][o[1]+0][o[2]+1],
212 c->d[o[0]+1][o[1]+0][o[2]+1],
213 c->d[o[0]+1][o[1]+1][o[2]+1],
214 c->d[o[0]+0][o[1]+1][o[2]+1]};
215 /* Normal */
216#if 1
217 const btScalar gx[]={ d[1]-d[0],d[2]-d[3],
218 d[5]-d[4],d[6]-d[7]};
219 const btScalar gy[]={ d[3]-d[0],d[2]-d[1],
220 d[7]-d[4],d[6]-d[5]};
221 const btScalar gz[]={ d[4]-d[0],d[5]-d[1],
222 d[7]-d[3],d[6]-d[2]};
223 normal.setX(Lerp( Lerp(gx[0],gx[1],iy.f),
224 Lerp(gx[2],gx[3],iy.f),iz.f));
225 normal.setY(Lerp( Lerp(gy[0],gy[1],ix.f),
226 Lerp(gy[2],gy[3],ix.f),iz.f));
227 normal.setZ(Lerp( Lerp(gz[0],gz[1],ix.f),
228 Lerp(gz[2],gz[3],ix.f),iy.f));
229 normal = normal.normalized();
230#else
231 normal = btVector3(d[1]-d[0],d[3]-d[0],d[4]-d[0]).normalized();
232#endif
233 /* Distance */
234 const btScalar d0=Lerp(Lerp(d[0],d[1],ix.f),
235 Lerp(d[3],d[2],ix.f),iy.f);
236 const btScalar d1=Lerp(Lerp(d[4],d[5],ix.f),
237 Lerp(d[7],d[6],ix.f),iy.f);
238 return(Lerp(d0,d1,iz.f)-margin);
239 }
240 //
242 {
243 const btVector3 org=btVector3( (btScalar)c.c[0],
244 (btScalar)c.c[1],
245 (btScalar)c.c[2]) *
246 CELLSIZE*voxelsz;
247 for(int k=0;k<=CELLSIZE;++k)
248 {
249 const btScalar z=voxelsz*k+org.z();
250 for(int j=0;j<=CELLSIZE;++j)
251 {
252 const btScalar y=voxelsz*j+org.y();
253 for(int i=0;i<=CELLSIZE;++i)
254 {
255 const btScalar x=voxelsz*i+org.x();
256 c.d[i][j][k]=DistanceToShape( btVector3(x,y,z),
257 c.pclient);
258 }
259 }
260 }
261 }
262 //
263 static inline btScalar DistanceToShape(const btVector3& x,
264 const btCollisionShape* shape)
265 {
266 btTransform unit;
267 unit.setIdentity();
268 if(shape->isConvex())
269 {
271 const btConvexShape* csh=static_cast<const btConvexShape*>(shape);
272 return(btGjkEpaSolver2::SignedDistance(x,0,csh,unit,res));
273 }
274 return(0);
275 }
276 //
277 static inline IntFrac Decompose(btScalar x)
278 {
279 /* That one need a lot of improvements... */
280 /* Remove test, faster floor... */
281 IntFrac r;
282 x/=CELLSIZE;
283 const int o=x<0?(int)(-x+1):0;
284 x+=o;r.b=(int)x;
285 const btScalar k=(x-r.b)*CELLSIZE;
286 r.i=(int)k;r.f=k-r.i;r.b-=o;
287 return(r);
288 }
289 //
291 {
292 return(a+(b-a)*t);
293 }
294
295
296
297 //
298 static inline unsigned int Hash(int x,int y,int z,const btCollisionShape* shape)
299 {
300 struct btS
301 {
302 int x,y,z;
303 void* p;
304 };
305
306 btS myset;
307
308 myset.x=x;myset.y=y;myset.z=z;myset.p=(void*)shape;
309 const void* ptr = &myset;
310
311 unsigned int result = HsiehHash<sizeof(btS)/4> (ptr);
312
313
314 return result;
315 }
316};
317
318
319#endif //BT_SPARSE_SDF_H
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:292
unsigned int HsiehHash(const void *pdata)
btSparseSdf implementation by Nathanael Presson
Definition: btSparseSDF.h:25
The btAlignedObjectArray template class uses a subset of the stl::vector interface for its methods It...
The btCollisionShape class provides an interface for collision shapes that can be shared among btColl...
bool isConvex() const
The btConvexShape is an abstract shape interface, implemented by all convex shapes such as btBoxShape...
Definition: btConvexShape.h:32
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:172
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:84
void setZ(btScalar _z)
Set the z value.
Definition: btVector3.h:583
const btScalar & z() const
Return the z value.
Definition: btVector3.h:591
btVector3 normalized() const
Return a normalized version of this vector.
Definition: btVector3.h:964
void setY(btScalar _y)
Set the y value.
Definition: btVector3.h:581
void setX(btScalar _x)
Set the x value.
Definition: btVector3.h:579
const btScalar & x() const
Return the x value.
Definition: btVector3.h:587
const btScalar & y() const
Return the y value.
Definition: btVector3.h:589
static btScalar SignedDistance(const btVector3 &position, btScalar margin, const btConvexShape *shape, const btTransform &wtrs, sResults &results)
Definition: btGjkEpa2.cpp:966
const btCollisionShape * pclient
Definition: btSparseSDF.h:61
btScalar d[CELLSIZE+1][CELLSIZE+1][CELLSIZE+1]
Definition: btSparseSDF.h:57
void GarbageCollect(int lifetime=256)
Definition: btSparseSDF.h:110
static IntFrac Decompose(btScalar x)
Definition: btSparseSDF.h:277
void Reset()
Definition: btSparseSDF.h:90
static btScalar DistanceToShape(const btVector3 &x, const btCollisionShape *shape)
Definition: btSparseSDF.h:263
int RemoveReferences(btCollisionShape *pcs)
Definition: btSparseSDF.h:136
int m_clampCells
Definition: btSparseSDF.h:72
btAlignedObjectArray< Cell * > cells
Definition: btSparseSDF.h:68
btScalar Evaluate(const btVector3 &x, const btCollisionShape *shape, btVector3 &normal, btScalar margin)
Definition: btSparseSDF.h:158
void BuildCell(Cell &c)
Definition: btSparseSDF.h:241
static btScalar Lerp(btScalar a, btScalar b, btScalar t)
Definition: btSparseSDF.h:290
static unsigned int Hash(int x, int y, int z, const btCollisionShape *shape)
Definition: btSparseSDF.h:298
btScalar voxelsz
Definition: btSparseSDF.h:69
void Initialize(int hashsize=2383, int clampCells=256 *1024)
Definition: btSparseSDF.h:81