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replace rand() with MarsenneTwister generator

This commit is contained in:
Massimiliano Corsini 2009-01-09 14:35:46 +00:00
parent 51e1718626
commit 3586a13438
1 changed files with 48 additions and 30 deletions
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78
vcg/complex/trimesh/point_sampling.h
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@ -89,25 +89,43 @@ class SurfaceSampling
typedef typename MetroMesh::FaceContainer FaceContainer;
public:
static math::SubtractiveRingRNG &SamplingRandomGenerator()
static math::MarsenneTwisterRNG &SamplingRandomGenerator()
{
static math::SubtractiveRingRNG rnd;
static math::MarsenneTwisterRNG rnd;
return rnd;
}
static unsigned int RandomInt(unsigned int i) { return SamplingRandomGenerator().generate(i); }
// Returns an integer random number in the [0,i-1] interval using the improve Marsenne-Twister method.
static unsigned int RandomInt(unsigned int i)
{
return (SamplingRandomGenerator().generate(0) % i);
}
// Returns a random number in the [0,1) real interval using the improved Marsenne-Twister method.
static double RandomDouble01()
{
return SamplingRandomGenerator().generate01();
}
// Returns a random number in the [0,1] real interval using the improved Marsenne-Twister.
static double RandomDouble01closed()
{
return SamplingRandomGenerator().generate01closed();
}
static void AllVertex(MetroMesh & m, VertexSampler &ps)
{
VertexIterator vi;
for(vi=m.vert.begin();vi!=m.vert.end();++vi)
if(!(*vi).IsD())
{
ps.AddVert(*vi);
}
VertexIterator vi;
for(vi=m.vert.begin();vi!=m.vert.end();++vi)
{
if(!(*vi).IsD())
{
ps.AddVert(*vi);
}
}
}
/// Sample the vertices in a weighted way. Each vertex has a probabiltiy of being chosen
/// Sample the vertices in a weighted way. Each vertex has a probability of being chosen
/// that is proportional to its quality.
/// It assumes that you are asking a number of vertices smaller than nv;
/// Algorithm:
@ -278,23 +296,23 @@ static void AllEdge(MetroMesh & m, VertexSampler &ps)
}
*/
// Generate the baricentric coords of a random point over a single face, with a uniform distribution over the triangle.
// It uses the parallelgoram folding trick.
// Generate the barycentric coords of a random point over a single face,
// with a uniform distribution over the triangle.
// It uses the parallelogram folding trick.
static CoordType RandomBaricentric()
{
CoordType interp;
interp[1] = (double)rand() / (double)RAND_MAX;
interp[2] = (double)rand() / (double)RAND_MAX;
if(interp[1] + interp[2] > 1.0)
{
interp[1] = 1.0 - interp[1];
interp[2] = 1.0 - interp[2];
}
assert(interp[1] + interp[2] <= 1.0);
interp[0]=1.0-(interp[1] + interp[2]);
return interp;
CoordType interp;
interp[1] = RandomDouble01();
interp[2] = RandomDouble01();
if(interp[1] + interp[2] > 1.0)
{
interp[1] = 1.0 - interp[1];
interp[2] = 1.0 - interp[2];
}
assert(interp[1] + interp[2] <= 1.0);
interp[0]=1.0-(interp[1] + interp[2]);
return interp;
}
static void StratifiedMontecarlo(MetroMesh & m, VertexSampler &ps,int sampleNum)
@ -308,7 +326,7 @@ static void StratifiedMontecarlo(MetroMesh & m, VertexSampler &ps,int sampleNum)
FaceIterator fi;
for(fi=m.face.begin(); fi != m.face.end(); fi++)
if(!(*fi).IsD())
{
{
// compute # samples in the current face (taking into account of the remainders)
floatSampleNum += 0.5*DoubleArea(*fi) * samplePerAreaUnit;
int faceSampleNum = (int) floatSampleNum;
@ -317,7 +335,7 @@ static void StratifiedMontecarlo(MetroMesh & m, VertexSampler &ps,int sampleNum)
for(int i=0; i < faceSampleNum; i++)
ps.AddFace(*fi,RandomBaricentric());
floatSampleNum -= (double) faceSampleNum;
}
}
}
static void Montecarlo(MetroMesh & m, VertexSampler &ps,int sampleNum)
{
@ -326,17 +344,17 @@ static void Montecarlo(MetroMesh & m, VertexSampler &ps,int sampleNum)
FaceIterator fi;
int i=0;
intervals[i]=std::make_pair(0,FacePointer(0));
// First loop: build a sequence of consective segments proportional to the triangle areas.
// First loop: build a sequence of consecutive segments proportional to the triangle areas.
for(fi=m.face.begin(); fi != m.face.end(); fi++)
if(!(*fi).IsD())
{
{
intervals[i+1]=std::make_pair(intervals[i].first+0.5*DoubleArea(*fi), &*fi);
++i;
}
ScalarType meshArea = intervals.back().first;
for(i=0;i<sampleNum;++i)
{
ScalarType val = meshArea * (double)rand() / (double)RAND_MAX;
ScalarType val = meshArea * RandomDouble01();
// lower_bound returns the furthermost iterator i in [first, last) such that, for every iterator j in [first, i), *j < value.
// E.g. An iterator pointing to the first element "not less than" val, or end() if every element is less than val.
typename std::vector<IntervalType>::iterator it = lower_bound(intervals.begin(),intervals.end(),std::make_pair(val,FacePointer(0)) );