372 lines
8.6 KiB
C++
372 lines
8.6 KiB
C++
/*
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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1. 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.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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///btSparseSdf implementation by Nathanael Presson
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#ifndef BT_SPARSE_SDF_H
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#define BT_SPARSE_SDF_H
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#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
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#include "BulletCollision/NarrowPhaseCollision/btGjkEpa2.h"
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// Fast Hash
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#if !defined (get16bits)
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#define get16bits(d) ((((unsigned int)(((const unsigned char *)(d))[1])) << 8)\
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+(unsigned int)(((const unsigned char *)(d))[0]) )
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#endif
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//
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// super hash function by Paul Hsieh
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//
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inline unsigned int HsiehHash (const char * data, int len) {
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unsigned int hash = len, tmp;
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len>>=2;
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/* Main loop */
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for (;len > 0; len--) {
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hash += get16bits (data);
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tmp = (get16bits (data+2) << 11) ^ hash;
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hash = (hash << 16) ^ tmp;
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data += 2*sizeof (unsigned short);
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hash += hash >> 11;
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}
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/* Force "avalanching" of final 127 bits */
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hash ^= hash << 3;
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hash += hash >> 5;
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hash ^= hash << 4;
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hash += hash >> 17;
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hash ^= hash << 25;
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hash += hash >> 6;
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return hash;
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}
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template <const int CELLSIZE>
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struct btSparseSdf
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{
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//
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// Inner types
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//
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struct IntFrac
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{
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int b;
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int i;
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btScalar f;
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};
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struct Cell
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{
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btScalar d[CELLSIZE + 1][CELLSIZE + 1][CELLSIZE + 1];
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int c[3];
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int puid;
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unsigned hash;
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const btCollisionShape* pclient;
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Cell* next;
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};
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//
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// Fields
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//
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btAlignedObjectArray<Cell*> cells;
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btScalar voxelsz;
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btScalar m_defaultVoxelsz;
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int puid;
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int ncells;
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int m_clampCells;
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int nprobes;
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int nqueries;
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~btSparseSdf()
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{
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Reset();
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}
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//
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// Methods
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//
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//
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void Initialize(int hashsize = 2383, int clampCells = 256 * 1024)
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{
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//avoid a crash due to running out of memory, so clamp the maximum number of cells allocated
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//if this limit is reached, the SDF is reset (at the cost of some performance during the reset)
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m_clampCells = clampCells;
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cells.resize(hashsize, 0);
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m_defaultVoxelsz = 0.25;
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Reset();
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}
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//
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void setDefaultVoxelsz(btScalar sz)
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{
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m_defaultVoxelsz = sz;
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}
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void Reset()
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{
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for (int i = 0, ni = cells.size(); i < ni; ++i)
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{
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Cell* pc = cells[i];
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cells[i] = 0;
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while (pc)
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{
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Cell* pn = pc->next;
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delete pc;
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pc = pn;
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}
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}
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voxelsz = m_defaultVoxelsz;
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puid = 0;
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ncells = 0;
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nprobes = 1;
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nqueries = 1;
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}
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//
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void GarbageCollect(int lifetime = 256)
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{
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const int life = puid - lifetime;
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for (int i = 0; i < cells.size(); ++i)
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{
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Cell*& root = cells[i];
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Cell* pp = 0;
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Cell* pc = root;
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while (pc)
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{
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Cell* pn = pc->next;
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if (pc->puid < life)
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{
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if (pp)
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pp->next = pn;
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else
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root = pn;
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delete pc;
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pc = pp;
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--ncells;
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}
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pp = pc;
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pc = pn;
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}
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}
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//printf("GC[%d]: %d cells, PpQ: %f\r\n",puid,ncells,nprobes/(btScalar)nqueries);
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nqueries = 1;
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nprobes = 1;
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++puid; ///@todo: Reset puid's when int range limit is reached */
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/* else setup a priority list... */
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}
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//
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int RemoveReferences(btCollisionShape* pcs)
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{
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int refcount = 0;
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for (int i = 0; i < cells.size(); ++i)
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{
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Cell*& root = cells[i];
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Cell* pp = 0;
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Cell* pc = root;
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while (pc)
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{
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Cell* pn = pc->next;
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if (pc->pclient == pcs)
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{
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if (pp)
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pp->next = pn;
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else
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root = pn;
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delete pc;
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pc = pp;
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++refcount;
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}
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pp = pc;
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pc = pn;
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}
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}
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return (refcount);
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}
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//
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btScalar Evaluate(const btVector3& x,
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const btCollisionShape* shape,
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btVector3& normal,
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btScalar margin)
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{
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/* Lookup cell */
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const btVector3 scx = x / voxelsz;
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const IntFrac ix = Decompose(scx.x());
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const IntFrac iy = Decompose(scx.y());
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const IntFrac iz = Decompose(scx.z());
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const unsigned h = Hash(ix.b, iy.b, iz.b, shape);
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Cell*& root = cells[static_cast<int>(h % cells.size())];
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Cell* c = root;
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++nqueries;
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while (c)
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{
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++nprobes;
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if ((c->hash == h) &&
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(c->c[0] == ix.b) &&
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(c->c[1] == iy.b) &&
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(c->c[2] == iz.b) &&
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(c->pclient == shape))
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{
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break;
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}
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else
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{
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// printf("c->hash/c[0][1][2]=%d,%d,%d,%d\n", c->hash, c->c[0], c->c[1],c->c[2]);
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//printf("h,ixb,iyb,izb=%d,%d,%d,%d\n", h,ix.b, iy.b, iz.b);
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c = c->next;
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}
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}
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if (!c)
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{
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++nprobes;
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++ncells;
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//int sz = sizeof(Cell);
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if (ncells > m_clampCells)
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{
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static int numResets = 0;
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numResets++;
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// printf("numResets=%d\n",numResets);
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Reset();
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}
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c = new Cell();
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c->next = root;
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root = c;
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c->pclient = shape;
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c->hash = h;
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c->c[0] = ix.b;
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c->c[1] = iy.b;
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c->c[2] = iz.b;
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BuildCell(*c);
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}
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c->puid = puid;
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/* Extract infos */
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const int o[] = {ix.i, iy.i, iz.i};
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const btScalar d[] = {c->d[o[0] + 0][o[1] + 0][o[2] + 0],
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c->d[o[0] + 1][o[1] + 0][o[2] + 0],
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c->d[o[0] + 1][o[1] + 1][o[2] + 0],
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c->d[o[0] + 0][o[1] + 1][o[2] + 0],
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c->d[o[0] + 0][o[1] + 0][o[2] + 1],
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c->d[o[0] + 1][o[1] + 0][o[2] + 1],
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c->d[o[0] + 1][o[1] + 1][o[2] + 1],
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c->d[o[0] + 0][o[1] + 1][o[2] + 1]};
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/* Normal */
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#if 1
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const btScalar gx[] = {d[1] - d[0], d[2] - d[3],
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d[5] - d[4], d[6] - d[7]};
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const btScalar gy[] = {d[3] - d[0], d[2] - d[1],
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d[7] - d[4], d[6] - d[5]};
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const btScalar gz[] = {d[4] - d[0], d[5] - d[1],
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d[7] - d[3], d[6] - d[2]};
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normal.setX(Lerp(Lerp(gx[0], gx[1], iy.f),
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Lerp(gx[2], gx[3], iy.f), iz.f));
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normal.setY(Lerp(Lerp(gy[0], gy[1], ix.f),
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Lerp(gy[2], gy[3], ix.f), iz.f));
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normal.setZ(Lerp(Lerp(gz[0], gz[1], ix.f),
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Lerp(gz[2], gz[3], ix.f), iy.f));
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normal.safeNormalize();
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#else
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normal = btVector3(d[1] - d[0], d[3] - d[0], d[4] - d[0]).normalized();
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#endif
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/* Distance */
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const btScalar d0 = Lerp(Lerp(d[0], d[1], ix.f),
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Lerp(d[3], d[2], ix.f), iy.f);
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const btScalar d1 = Lerp(Lerp(d[4], d[5], ix.f),
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Lerp(d[7], d[6], ix.f), iy.f);
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return (Lerp(d0, d1, iz.f) - margin);
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}
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//
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void BuildCell(Cell& c)
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{
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const btVector3 org = btVector3((btScalar)c.c[0],
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(btScalar)c.c[1],
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(btScalar)c.c[2]) *
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CELLSIZE * voxelsz;
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for (int k = 0; k <= CELLSIZE; ++k)
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{
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const btScalar z = voxelsz * k + org.z();
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for (int j = 0; j <= CELLSIZE; ++j)
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{
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const btScalar y = voxelsz * j + org.y();
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for (int i = 0; i <= CELLSIZE; ++i)
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{
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const btScalar x = voxelsz * i + org.x();
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c.d[i][j][k] = DistanceToShape(btVector3(x, y, z),
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c.pclient);
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}
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}
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}
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}
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//
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static inline btScalar DistanceToShape(const btVector3& x,
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const btCollisionShape* shape)
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{
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btTransform unit;
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unit.setIdentity();
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if (shape->isConvex())
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{
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btGjkEpaSolver2::sResults res;
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const btConvexShape* csh = static_cast<const btConvexShape*>(shape);
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return (btGjkEpaSolver2::SignedDistance(x, 0, csh, unit, res));
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}
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return (0);
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}
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//
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static inline IntFrac Decompose(btScalar x)
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{
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/* That one need a lot of improvements... */
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/* Remove test, faster floor... */
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IntFrac r;
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x /= CELLSIZE;
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const int o = x < 0 ? (int)(-x + 1) : 0;
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x += o;
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r.b = (int)x;
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const btScalar k = (x - r.b) * CELLSIZE;
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r.i = (int)k;
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r.f = k - r.i;
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r.b -= o;
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return (r);
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}
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//
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static inline btScalar Lerp(btScalar a, btScalar b, btScalar t)
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{
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return (a + (b - a) * t);
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}
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//
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static inline unsigned int Hash(int x, int y, int z, const btCollisionShape* shape)
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{
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struct btS
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{
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int x, y, z, w;
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void* p;
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};
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btS myset;
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//memset may be needed in case of additional (uninitialized) padding!
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//memset(&myset, 0, sizeof(btS));
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myset.x = x;
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myset.y = y;
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myset.z = z;
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myset.w = 0;
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myset.p = (void*)shape;
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const char* ptr = (const char*)&myset;
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unsigned int result = HsiehHash(ptr, sizeof(btS) );
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return result;
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}
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};
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#endif //BT_SPARSE_SDF_H
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