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Refactorized to a uniform naming and parameters the various templated functions for generating random points 

GenerateBarycentricUniform
GeneratePointInBox3Uniform
GeneratePointOnUnitSphereUniform
GeneratePointInUnitBallUniform
This commit is contained in:
Paolo Cignoni 2013-06-24 08:34:53 +00:00
parent 8d9d7b9009
commit 90bb95a971
1 changed files with 46 additions and 6 deletions
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52
vcg/math/random_generator.h
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@ -62,20 +62,42 @@ public:
/// Generates a random number in the (0,1) real interval. /// Generates a random number in the (0,1) real interval.
virtual double generate01open()=0; virtual double generate01open()=0;
virtual double generateRange(double minV, double maxV) { return minV+(maxV-minV)*generate01(); } virtual double generateRange(double minV, double maxV) { return minV+(maxV-minV)*generate01(); }
}; };
/// \brief 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.
template <class ScalarType, class GeneratorType> template <class ScalarType, class GeneratorType>
void GeneratePointInBox3Uniform(GeneratorType &rnd, const Box3<ScalarType> &bb, Point3<ScalarType> &p) vcg::Point3<ScalarType> GenerateBarycentricUniform(GeneratorType &rnd)
{ {
p = Point3<ScalarType>( vcg::Point3<ScalarType> interp;
(ScalarType) rnd.generateRange(double(bb.min[0]),double(bb.max[0])), interp[1] = rnd.generate01();
interp[2] = rnd.generate01();
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;
}
/// \brief Generate a random point insidie a box with uniform distribution
template <class ScalarType, class GeneratorType>
vcg::Point3<ScalarType> GeneratePointInBox3Uniform(GeneratorType &rnd, const Box3<ScalarType> &bb)
{
return Point3<ScalarType>(
(ScalarType) rnd.generateRange(double(bb.min[0]),double(bb.max[0])),
(ScalarType) rnd.generateRange(double(bb.min[1]),double(bb.max[1])), (ScalarType) rnd.generateRange(double(bb.min[1]),double(bb.max[1])),
(ScalarType) rnd.generateRange(double(bb.min[2]),double(bb.max[2])) (ScalarType) rnd.generateRange(double(bb.min[2]),double(bb.max[2]))
); );
} }
/*
/** \brief Generate a point over the surface of a unit sphere with uniform distribution
* This is the algorithm proposed by George Marsaglia [1] * This is the algorithm proposed by George Marsaglia [1]
* to generate a point over a unit sphere * to generate a point over a unit sphere
* Independently generate V1 and V2, taken from a uniform distribution on (-1,1) such that * Independently generate V1 and V2, taken from a uniform distribution on (-1,1) such that
@ -87,8 +109,9 @@ void GeneratePointInBox3Uniform(GeneratorType &rnd, const Box3<ScalarType> &bb,
* Marsaglia, G. "Choosing a Point from the Surface of a Sphere." Ann. Math. Stat. 43, 645-646, 1972. * Marsaglia, G. "Choosing a Point from the Surface of a Sphere." Ann. Math. Stat. 43, 645-646, 1972.
*/ */
template <class ScalarType, class GeneratorType> template <class ScalarType, class GeneratorType>
void GeneratePointOnUnitSphereUniform(GeneratorType &rnd, vcg::Point3<ScalarType> &p) vcg::Point3<ScalarType> GeneratePointOnUnitSphereUniform(GeneratorType &rnd)
{ {
vcg::Point3<ScalarType> p;
double x,y,s; double x,y,s;
do do
{ {
@ -99,8 +122,25 @@ void GeneratePointOnUnitSphereUniform(GeneratorType &rnd, vcg::Point3<ScalarType
p[0]= ScalarType(2 * x * sqrt(1-s)); p[0]= ScalarType(2 * x * sqrt(1-s));
p[1]= ScalarType(2 * y * sqrt(1-s)); p[1]= ScalarType(2 * y * sqrt(1-s));
p[2]= ScalarType(1-2*s); p[2]= ScalarType(1-2*s);
return p;
} }
/// \brief generate a point inside a unit sphere with uniform distribution
template <class ScalarType, class GeneratorType>
vcg::Point3<ScalarType> GeneratePointInUnitBallUniform(GeneratorType &rnd)
{
vcg::Point3<ScalarType> p;
while(1)
{
p.Import(Point3d(0.5-rnd.generate01(),0.5-rnd.generate01(),0.5-rnd.generate01()));
if(SquaredNorm(p)<=0.25){
p*=2;
return p;
}
}
}
/** /**
* Uniform RNG derived from a STL extension of sgi. * Uniform RNG derived from a STL extension of sgi.
* *