assimp/code/ImproveCacheLocality.cpp

384 lines
12 KiB
C++

/*
---------------------------------------------------------------------------
Open Asset Import Library (ASSIMP)
---------------------------------------------------------------------------
Copyright (c) 2006-2008, ASSIMP Development Team
All rights reserved.
Redistribution and use of this software in source and binary forms,
with or without modification, are permitted provided that the following
conditions are met:
* Redistributions of source code must retain the above
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following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the
following disclaimer in the documentation and/or other
materials provided with the distribution.
* Neither the name of the ASSIMP team, nor the names of its
contributors may be used to endorse or promote products
derived from this software without specific prior
written permission of the ASSIMP Development Team.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
---------------------------------------------------------------------------
*/
/** @file Implementation of the post processing to improve the
* cache locality of a mesh.
* <br>
* The algorithm is roughly basing on this paper:
* http://www.cs.princeton.edu/gfx/pubs/Sander_2007_%3ETR/tipsy.pdf
*/
// STL headers
#include <vector>
#include <stack>
#include <queue>
// public ASSIMP headers
#include "../include/DefaultLogger.h"
#include "../include/aiPostProcess.h"
#include "../include/aiMesh.h"
#include "../include/aiScene.h"
// internal headers
#include "ImproveCacheLocality.h"
#include "VertexTriangleAdjacency.h"
using namespace Assimp;
#if _MSC_VER >= 1400
# define sprintf sprintf_s
#endif
// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
ImproveCacheLocalityProcess::ImproveCacheLocalityProcess()
{
// nothing to do here
configCacheDepth = 12; // hardcoded to 12 at the moment
}
// ------------------------------------------------------------------------------------------------
// Destructor, private as well
ImproveCacheLocalityProcess::~ImproveCacheLocalityProcess()
{
// nothing to do here
}
// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool ImproveCacheLocalityProcess::IsActive( unsigned int pFlags) const
{
return (pFlags & aiProcess_ImproveCacheLocality) != 0;
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void ImproveCacheLocalityProcess::Execute( aiScene* pScene)
{
DefaultLogger::get()->debug("ImproveCacheLocalityProcess begin");
for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
{
this->ProcessMesh( pScene->mMeshes[a],a);
}
DefaultLogger::get()->debug("ImproveCacheLocalityProcess finished. ");
}
// ------------------------------------------------------------------------------------------------
// Improves the cache coherency of a specific mesh
void ImproveCacheLocalityProcess::ProcessMesh( aiMesh* pMesh, unsigned int meshNum)
{
ai_assert(NULL != pMesh);
// check whether the input data is valid ->
// - there must be vertices and faces (haha)
// - all faces must be triangulated
if (!pMesh->HasFaces() || !pMesh->HasPositions())return;
// find the input ACMR ...
unsigned int* piFIFOStack = new unsigned int[this->configCacheDepth];
::memset(piFIFOStack,0xff,this->configCacheDepth*sizeof(unsigned int));
unsigned int* piCur = piFIFOStack;
const unsigned int* const piCurEnd = piFIFOStack + this->configCacheDepth;
// count the number of cache misses
unsigned int iCacheMisses = 0;
const aiFace* const pcEnd = pMesh->mFaces+pMesh->mNumFaces;
for (const aiFace* pcFace = pMesh->mFaces;pcFace != pcEnd;++pcFace)
{
if (3 != pcFace->mNumIndices)
{
DefaultLogger::get()->error("Unable to improve cache locality of non-triangulated faces");
delete[] piFIFOStack;
return;
}
// although it has not been tested, I'm quite sure degenerated triangles
// would crash if the algorithm was applied to them
#if (defined _DEBUG)
if (pcFace->mIndices[0] == pcFace->mIndices[1] ||
pcFace->mIndices[2] == pcFace->mIndices[1] ||
pcFace->mIndices[2] == pcFace->mIndices[0])
{
DefaultLogger::get()->error("ImproveCacheLocalityProcess: There may be no degenerated triangles ");
return;
}
#endif
for (unsigned int qq = 0; qq < 3;++qq)
{
bool bInCache = false;
for (unsigned int* pp = piFIFOStack;pp < piCurEnd;++pp)
{
if (*pp == pcFace->mIndices[qq])
{
// the vertex is in cache
bInCache = true;
break;
}
}
if (!bInCache)
{
++iCacheMisses;
if (piCurEnd == piCur)piCur = piFIFOStack;
*piCur++ = pcFace->mIndices[qq];
}
}
}
delete[] piFIFOStack;
float fACMR = (float)iCacheMisses / pMesh->mNumFaces;
if (3.0 == fACMR)
{
char szBuff[128]; // should be sufficiently large in every case
// the JoinIdenticalVertices process has not been executed on this
// mesh, otherwise this value would normally be at least minimally#
// smaller than 3.0 ...
::sprintf(szBuff,"Mesh %i: JIV-Step has not been executed properly (precondition)",meshNum);
DefaultLogger::get()->warn(szBuff);
return;
}
// first we need to build a vertex-triangle adjacency list
VertexTriangleAdjacency adj(pMesh->mFaces,pMesh->mNumFaces, pMesh->mNumVertices,true);
// build a list to store per-vertex caching time stamps
unsigned int* const piCachingStamps = new unsigned int[pMesh->mNumVertices];
::memset(piCachingStamps,0x0,pMesh->mNumVertices*sizeof(unsigned int));
// allocate an empty output index buffer. We store the output
// indices in one large array. Since the number of triangles
// won't change the input faces can be reused. This is how we save
// thousands of redundant mini allocations for aiFace::mIndices
const unsigned int iIdxCnt = pMesh->mNumFaces*3;
unsigned int* const piIBOutput = new unsigned int[iIdxCnt];
unsigned int* piCSIter = piIBOutput;
// allocate the flag array to hold the information
// whether a face has already been emitted or not
std::vector<bool> abEmitted(pMesh->mNumFaces,false);
// dead-end vertex index stack
std::stack<unsigned int> sDeadEndVStack;
// create a copy of the piNumTriPtr buffer
unsigned int* const piNumTriPtr = adj.mLiveTriangles;
const unsigned int* const piNumTriPtrNoModify = new unsigned int[pMesh->mNumVertices];
::memcpy(const_cast<unsigned int* const> (piNumTriPtrNoModify),piNumTriPtr,
pMesh->mNumVertices * sizeof(unsigned int));
// get the largest number of referenced triangles
// and allocate the "candidate buffer"
unsigned int iMaxRefTris = 0;
{
const unsigned int* piCur = adj.mLiveTriangles;
const unsigned int* const piCurEnd = adj.mLiveTriangles+pMesh->mNumVertices;
for (;piCur != piCurEnd;++piCur)
iMaxRefTris = std::max(iMaxRefTris,*piCur);
}
unsigned int* piCandidates = new unsigned int[iMaxRefTris*3];
iCacheMisses = 0;
/** PSEUDOCODE for the algorithm
A = Build-Adjacency(I) Vertex-triangle adjacency
L = Get-Triangle-Counts(A) Per-vertex live triangle counts
C = Zero(Vertex-Count(I)) Per-vertex caching time stamps
D = Empty-Stack() Dead-end vertex stack
E = False(Triangle-Count(I)) Per triangle emitted flag
O = Empty-Index-Buffer() Empty output buffer
f = 0 Arbitrary starting vertex
s = k+1, i = 1 Time stamp and cursor
while f >= 0 For all valid fanning vertices
N = Empty-Set() 1-ring of next candidates
for each Triangle t in Neighbors(A, f)
if !Emitted(E,t)
for each Vertex v in t
Append(O,v) Output vertex
Push(D,v) Add to dead-end stack
Insert(N,v) Register as candidate
L[v] = L[v]-1 Decrease live triangle count
if s-C[v] > k If not in cache
C[v] = s Set time stamp
s = s+1 Increment time stamp
E[t] = true Flag triangle as emitted
Select next fanning vertex
f = Get-Next-Vertex(I,i,k,N,C,s,L,D)
return O
*/
int ivdx = 0;
int ics = 1;
int iStampCnt = this->configCacheDepth+1;
while (ivdx >= 0)
{
unsigned int icnt = piNumTriPtrNoModify[ivdx];
unsigned int* piList = adj.GetAdjacentTriangles(ivdx);
unsigned int* piCurCandidate = piCandidates;
// get all triangles in the neighborhood
for (unsigned int tri = 0; tri < icnt;++tri)
{
// if they have not yet been emitted, add them to the output IB
const unsigned int fidx = *piList++;
if (!abEmitted[fidx])
{
// so iterate through all vertices of the current triangle
const aiFace* pcFace = &pMesh->mFaces[ fidx ];
const unsigned int* const p2 = pcFace->mIndices+3;
for (unsigned int* p = pcFace->mIndices;p != p2;++p)
{
const unsigned int dp = *p;
// the current vertex won't have any free triangles after this step
if (ivdx != dp)
{
// append the vertex to the dead-end stack
sDeadEndVStack.push(dp);
// register as candidate for the next step
*piCurCandidate++ = dp;
// decrease the per-vertex triangle counts
piNumTriPtr[dp]--;
}
// append the vertex to the output index buffer
*piCSIter++ = dp;
// if the vertex is not yet in cache, set its cache count
if (iStampCnt-piCachingStamps[dp] > this->configCacheDepth)
{
piCachingStamps[dp] = iStampCnt++;
++iCacheMisses;
}
}
// flag triangle as emitted
abEmitted[fidx] = true;
}
}
// the vertex has now no living adjacent triangles anymore
piNumTriPtr[ivdx] = 0;
// get next fanning vertex
ivdx = -1;
int max_priority = -1;
for (unsigned int* piCur = piCandidates;piCur != piCurCandidate;++piCur)
{
register const unsigned int dp = *piCur;
// must have live triangles
if (piNumTriPtr[dp] > 0)
{
int priority = 0;
// will the vertex be in cache, even after fanning occurs?
unsigned int tmp;
if ((tmp = iStampCnt-piCachingStamps[dp]) + 2*piNumTriPtr[dp] <= this->configCacheDepth)
priority = tmp;
// keep best candidate
if (priority > max_priority)
{
max_priority = priority;
ivdx = dp;
}
}
}
// did we reach a dead end?
if (-1 == ivdx)
{
// need to get a non-local vertex for which we have a good
// chance that it is still in the cache ...
while (!sDeadEndVStack.empty())
{
unsigned int iCachedIdx = sDeadEndVStack.top();
sDeadEndVStack.pop();
if (piNumTriPtr[ iCachedIdx ] > 0)
{
ivdx = iCachedIdx;
break;
}
}
if (-1 == ivdx)
{
// well, there isn't such a vertex. Simply get the next
// vertex in input order and hope it is not too bad ...
while (ics < (int)pMesh->mNumVertices)
{
++ics;
if (piNumTriPtr[ics] > 0)
{
ivdx = ics;
break;
}
}
}
}
}
if (!DefaultLogger::isNullLogger())
{
char szBuff[128]; // should be sufficiently large in every case
float fACMR2 = (float)iCacheMisses / pMesh->mNumFaces;
::sprintf(szBuff,"Mesh %i | ACMR in: %f out: %f | ~%.1f%%",meshNum,fACMR,fACMR2,
((fACMR - fACMR2) / fACMR) * 100.f);
DefaultLogger::get()->info(szBuff);
}
// sort the output index buffer back to the input array
piCSIter = piIBOutput;
for (aiFace* pcFace = pMesh->mFaces; pcFace != pcEnd;++pcFace)
{
pcFace->mIndices[0] = *piCSIter++;
pcFace->mIndices[1] = *piCSIter++;
pcFace->mIndices[2] = *piCSIter++;
}
// delete temporary storage
delete[] piCachingStamps;
delete[] piIBOutput;
delete[] piCandidates;
delete[] piNumTriPtrNoModify;
}