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Spherical Harmonics are templatized on the number of coefficients

This commit is contained in:
Paolo Cignoni 2008-10-08 14:01:34 +00:00
parent 2da37bd5f7
commit 39e2cf2b3e
1 changed files with 27 additions and 30 deletions
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57
vcg/math/spherical_harmonics.h
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@ -35,12 +35,12 @@ namespace vcg{
namespace math{
/**
* Although the Real Spherical Harmonic Function is correctly defined over any
* Although the Real Spherical Harmonic Function is correctly defined over any
* positive l and any -l <= m <= l, the two internal functions computing the
* imaginary and real parts of the Complex Spherical Harmonic Functions are defined
* for positive m only.
*/
template <typename ScalarType>
template <typename ScalarType, int MAX_BAND>
class SphericalHarmonics{
private :
@ -48,25 +48,25 @@ private :
{
return Sqrt( ( (2.0*l + 1.0) * Factorial<ScalarType>(l-m) ) / (4.0 * M_PI * Factorial<ScalarType>(l + m)) );;
}
inline static ScalarType complex_spherical_harmonic_re(unsigned l, unsigned m, ScalarType theta, ScalarType phi)
{
return scaling_factor(l, m) * Legendre<ScalarType>::AssociatedPolynomial(l, m, Cos(theta), Sin(theta)) * Cos(m * phi);
}
inline static ScalarType complex_spherical_harmonic_im(unsigned l, unsigned m, ScalarType theta, ScalarType phi)
{
return scaling_factor(l, m) * Legendre<ScalarType>::AssociatedPolynomial(l, m, Cos(theta), Sin(theta)) * Sin(m * phi);
}
ScalarType * coefficients;
int max_band;
ScalarType coefficients[MAX_BAND * MAX_BAND];
static const int max_band = MAX_BAND;
public :
/**
* Returns the Real Spherical Harmonic Function
*
*
* l is any positive integer,
* m is such that -l <= m <= l
* theta is inside [0, PI]
@ -75,46 +75,43 @@ public :
static ScalarType Real(unsigned l, int m, ScalarType theta, ScalarType phi)
{
assert((int)-l <= m && m <= (int)l && theta >= 0 && theta <= M_PI && phi >= 0 && phi <= 2 * M_PI);
if (m > 0) return SQRT_TWO * complex_spherical_harmonic_re(l, m, theta, phi);
else if (m == 0) return scaling_factor(l, 0) * Legendre<ScalarType>::Polynomial(l, Cos(theta));
else return SQRT_TWO * complex_spherical_harmonic_im(l, -m, theta, phi);
}
typedef ScalarType (*PolarFunction) (ScalarType theta, ScalarType phi);
static SphericalHarmonics Project(PolarFunction fun, unsigned max_band, unsigned n_samples)
static SphericalHarmonics Project(PolarFunction fun, unsigned n_samples)
{
const ScalarType weight = 4 * M_PI;
unsigned sqrt_n_samples = (unsigned int) Sqrt((int)n_samples);
unsigned actual_n_samples = sqrt_n_samples * sqrt_n_samples;
unsigned n_coeff = max_band * max_band;
unsigned n_coeff = MAX_BAND * MAX_BAND;
ScalarType one_over_n = 1.0/(ScalarType)sqrt_n_samples;
RandomGenerator rand;
SphericalHarmonics sph;
sph.coefficients = new ScalarType[n_coeff];
sph.max_band = max_band;
int i = 0;
for (unsigned k = 0; k < n_coeff; k++ ) sph.coefficients[k] = 0;
for (unsigned a = 0; a < sqrt_n_samples; ++a )
{
for (unsigned b = 0; b < sqrt_n_samples; ++b)
{
ScalarType x = (a + rand(INT_MAX)/(ScalarType)INT_MAX) * one_over_n;
ScalarType y = (b + rand(INT_MAX)/(ScalarType)INT_MAX) * one_over_n;
ScalarType theta = 2.0 * Acos(Sqrt(1.0 - x));
ScalarType phi = 2.0 * M_PI * y;
for (int l = 0; l < (int)max_band; ++l)
{
for (int m = -l; m <= l; ++m)
@ -126,20 +123,20 @@ public :
i++;
}
}
ScalarType factor = weight / actual_n_samples;
for(i = 0; i < (int)n_coeff; ++i)
{
sph.coefficients[i] *= factor;
}
return sph;
}
ScalarType operator()(ScalarType theta, ScalarType phi)
{
ScalarType f = 0;
for (int l = 0; l < max_band; ++l)
{
for (int m = -l; m <= l; ++m)
@ -148,7 +145,7 @@ public :
f += (coefficients[index] * Real(l, m, theta, phi));
}
}
return f;
}
};