mirror of
https://github.com/godotengine/godot.git
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320 lines
7.2 KiB
C++
320 lines
7.2 KiB
C++
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/*
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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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// Modified Paul Hsieh hash
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template <const int DWORDLEN>
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unsigned int HsiehHash(const void* pdata)
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{
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const unsigned short* data=(const unsigned short*)pdata;
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unsigned hash=DWORDLEN<<2,tmp;
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for(int i=0;i<DWORDLEN;++i)
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{
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hash += data[0];
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tmp = (data[1]<<11)^hash;
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hash = (hash<<16)^tmp;
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data += 2;
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hash += hash>>11;
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}
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hash^=hash<<3;hash+=hash>>5;
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hash^=hash<<4;hash+=hash>>17;
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hash^=hash<<25;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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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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//
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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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Reset();
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}
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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 =0.25;
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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) pp->next=pn; else root=pn;
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delete pc;pc=pp;--ncells;
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}
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pp=pc;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) pp->next=pn; else root=pn;
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delete pc;pc=pp;++refcount;
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}
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pp=pc;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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{ break; }
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else
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{ c=c->next; }
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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;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;c->c[1]=iy.b;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 = normal.normalized();
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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;r.b=(int)x;
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const btScalar k=(x-r.b)*CELLSIZE;
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r.i=(int)k;r.f=k-r.i;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;
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void* p;
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};
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btS myset;
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myset.x=x;myset.y=y;myset.z=z;myset.p=(void*)shape;
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const void* ptr = &myset;
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unsigned int result = HsiehHash<sizeof(btS)/4> (ptr);
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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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