seamless cubemap filtering.
parent
2ec37026be
commit
d11d7a5f38
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// This code is in the public domain -- castanyo@yahoo.es
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#include <nvmath/SphericalHarmonic.h>
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using namespace nv;
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namespace
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{
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// Basic integer factorial.
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inline static int factorial( int v )
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{
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const static int fac_table[] = { 1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800 };
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if(v <= 11){
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return fac_table[v];
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}
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int result = v;
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while (--v > 0) {
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result *= v;
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}
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return result;
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}
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// Double factorial.
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// Defined as: n!! = n*(n - 2)*(n - 4)..., n!!(0,-1) = 1.
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inline static int doubleFactorial( int x )
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{
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if (x == 0 || x == -1) {
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return 1;
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}
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int result = x;
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while ((x -= 2) > 0) {
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result *= x;
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}
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return result;
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}
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/// Normalization constant for spherical harmonic.
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/// @param l is the band.
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/// @param m is the argument, in the range [0, m]
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inline static float K( int l, int m )
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{
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nvDebugCheck( m >= 0 );
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return sqrtf(((2 * l + 1) * factorial(l - m)) / (4 * PI * factorial(l + m)));
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}
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/// Normalization constant for hemispherical harmonic.
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inline static float HK( int l, int m )
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{
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nvDebugCheck( m >= 0 );
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return sqrtf(((2 * l + 1) * factorial(l - m)) / (2 * PI * factorial(l + m)));
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}
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/// Evaluate Legendre polynomial. */
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static float legendre( int l, int m, float x )
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{
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// piDebugCheck( m >= 0 );
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// piDebugCheck( m <= l );
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// piDebugCheck( fabs(x) <= 1 );
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// Rule 2 needs no previous results
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if (l == m) {
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return powf(-1.0f, float(m)) * doubleFactorial(2 * m - 1) * powf(1 - x*x, 0.5f * m);
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}
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// Rule 3 requires the result for the same argument of the previous band
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if (l == m + 1) {
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return x * (2 * m + 1) * legendrePolynomial(m, m, x);
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}
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// Main reccurence used by rule 1 that uses result of the same argument from
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// the previous two bands
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return (x * (2 * l - 1) * legendrePolynomial(l - 1, m, x) - (l + m - 1) * legendrePolynomial(l - 2, m, x)) / (l - m);
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}
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template <int l, int m> float legendre(float x);
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template <> float legendre<0, 0>(float ) {
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return 1;
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}
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template <> float legendre<1, 0>(float x) {
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return x;
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}
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template <> float legendre<1, 1>(float x) {
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return -sqrtf(1 - x * x);
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}
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template <> float legendre<2, 0>(float x) {
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return -0.5f + (3 * x * x) / 2;
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}
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template <> float legendre<2, 1>(float x) {
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return -3 * x * sqrtf(1 - x * x);
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}
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template <> float legendre<2, 2>(float x) {
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return -3 * (-1 + x * x);
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}
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template <> float legendre<3, 0>(float x) {
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return -(3 * x) / 2 + (5 * x * x * x) / 2;
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}
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template <> float legendre<3, 1>(float x) {
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return -3 * sqrtf(1 - x * x) / 2 * (-1 + 5 * x * x);
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}
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template <> float legendre<3, 2>(float x) {
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return -15 * (-x + x * x * x);
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}
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template <> float legendre<3, 3>(float x) {
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return -15 * powf(1 - x * x, 1.5f);
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}
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template <> float legendre<4, 0>(float x) {
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return 0.125f * (3.0f - 30.0f * x * x + 35.0f * x * x * x * x);
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}
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template <> float legendre<4, 1>(float x) {
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return -2.5f * x * sqrtf(1.0f - x * x) * (7.0f * x * x - 3.0f);
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}
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template <> float legendre<4, 2>(float x) {
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return -7.5f * (1.0f - 8.0f * x * x + 7.0f * x * x * x * x);
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}
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template <> float legendre<4, 3>(float x) {
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return -105.0f * x * powf(1 - x * x, 1.5f);
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}
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template <> float legendre<4, 4>(float x) {
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return 105.0f * (x * x - 1.0f) * (x * x - 1.0f);
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}
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} // namespace
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float nv::legendrePolynomial(int l, int m, float x)
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{
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switch(l)
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{
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case 0:
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return legendre<0, 0>(x);
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case 1:
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if(m == 0) return legendre<1, 0>(x);
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return legendre<1, 1>(x);
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case 2:
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if(m == 0) return legendre<2, 0>(x);
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else if(m == 1) return legendre<2, 1>(x);
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return legendre<2, 2>(x);
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case 3:
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if(m == 0) return legendre<3, 0>(x);
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else if(m == 1) return legendre<3, 1>(x);
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else if(m == 2) return legendre<3, 2>(x);
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return legendre<3, 3>(x);
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case 4:
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if(m == 0) return legendre<4, 0>(x);
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else if(m == 1) return legendre<4, 1>(x);
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else if(m == 2) return legendre<4, 2>(x);
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else if(m == 3) return legendre<4, 3>(x);
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else return legendre<4, 4>(x);
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}
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// Fallback to the expensive version.
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return legendre(l, m, x);
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}
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/**
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* Evaluate the spherical harmonic function for the given angles.
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* @param l is the band.
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* @param m is the argument, in the range [-l,l]
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* @param theta is the altitude, in the range [0, PI]
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* @param phi is the azimuth, in the range [0, 2*PI]
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*/
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float nv::shBasis( int l, int m, float theta, float phi )
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{
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if( m == 0 ) {
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// K(l, 0) = sqrt((2*l+1)/(4*PI))
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return sqrtf((2 * l + 1) / (4 * PI)) * legendrePolynomial(l, 0, cosf(theta));
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}
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else if( m > 0 ) {
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return sqrtf(2.0f) * K(l, m) * cosf(m * phi) * legendrePolynomial(l, m, cosf(theta));
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}
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else {
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return sqrtf(2.0f) * K(l, -m) * sinf(-m * phi) * legendrePolynomial(l, -m, cosf(theta));
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}
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}
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/**
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* Real spherical harmonic function of an unit vector. Uses the following
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* equalities to call the angular function:
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* x = sin(theta)*cos(phi)
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* y = sin(theta)*sin(phi)
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* z = cos(theta)
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*/
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float nv::shBasis( int l, int m, Vector3::Arg v )
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{
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float theta = acosf(v.z);
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float phi = atan2f(v.y, v.x);
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return shBasis( l, m, theta, phi );
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}
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/**
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* Evaluate the hemispherical harmonic function for the given angles.
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* @param l is the band.
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* @param m is the argument, in the range [-l,l]
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* @param theta is the altitude, in the range [0, PI/2]
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* @param phi is the azimuth, in the range [0, 2*PI]
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*/
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float nv::hshBasis( int l, int m, float theta, float phi )
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{
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if( m == 0 ) {
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// HK(l, 0) = sqrt((2*l+1)/(2*PI))
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return sqrtf((2 * l + 1) / (2 * PI)) * legendrePolynomial(l, 0, 2*cosf(theta)-1);
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}
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else if( m > 0 ) {
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return sqrtf(2.0f) * HK(l, m) * cosf(m * phi) * legendrePolynomial(l, m, 2*cosf(theta)-1);
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}
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else {
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return sqrtf(2.0f) * HK(l, -m) * sinf(-m * phi) * legendrePolynomial(l, -m, 2*cosf(theta)-1);
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}
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}
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/**
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* Real hemispherical harmonic function of an unit vector. Uses the following
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* equalities to call the angular function:
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* x = sin(theta)*cos(phi)
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* y = sin(theta)*sin(phi)
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* z = cos(theta)
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*/
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float nv::hshBasis( int l, int m, Vector3::Arg v )
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{
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float theta = acosf(v.z);
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float phi = atan2f(v.y, v.x);
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return hshBasis( l, m, theta, phi );
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}
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@ -0,0 +1,418 @@
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// This code is in the public domain -- castanyo@yahoo.es
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#ifndef NV_MATH_SPHERICALHARMONIC_H
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#define NV_MATH_SPHERICALHARMONIC_H
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#include "Vector.h"
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#include <string.h> // memcpy
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namespace nv
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{
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class Matrix;
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NVMATH_API float legendrePolynomial( int l, int m, float x ) NV_CONST;
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NVMATH_API float shBasis( int l, int m, float theta, float phi ) NV_CONST;
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NVMATH_API float shBasis( int l, int m, Vector3::Arg v ) NV_CONST;
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NVMATH_API float hshBasis( int l, int m, float theta, float phi ) NV_CONST;
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NVMATH_API float hshBasis( int l, int m, Vector3::Arg v ) NV_CONST;
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class Sh;
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float dot(const Sh & a, const Sh & b) NV_CONST;
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/// Spherical harmonic class.
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class Sh
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{
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friend class Sh2;
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friend class ShMatrix;
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public:
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/// Construct a spherical harmonic of the given order.
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Sh(int o) : m_order(o)
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{
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m_elemArray = new float[basisNum()];
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}
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/// Copy constructor.
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Sh(const Sh & sh) : m_order(sh.order())
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{
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m_elemArray = new float[basisNum()];
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memcpy(m_elemArray, sh.m_elemArray, sizeof(float) * basisNum());
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}
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/// Destructor.
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~Sh()
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{
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delete [] m_elemArray;
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m_elemArray = NULL;
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}
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/// Get number of bands.
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static int bandNum(int m_order) {
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return m_order + 1;
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}
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/// Get number of sh basis.
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static int basisNum(int m_order) {
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return (m_order + 1) * (m_order + 1);
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}
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/// Get the index for the given coefficients.
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static int index( int l, int m ) {
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return l * l + l + m;
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}
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/// Get sh order.
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int order() const
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{
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return m_order;
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}
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/// Get sh order.
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int bandNum() const
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{
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return bandNum(m_order);
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}
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/// Get sh order.
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int basisNum() const
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{
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return basisNum(m_order);
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}
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/// Get sh coefficient indexed by l,m.
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float elem( int l, int m ) const
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{
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return m_elemArray[index(l, m)];
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}
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/// Get sh coefficient indexed by l,m.
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float & elem( int l, int m )
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{
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return m_elemArray[index(l, m)];
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}
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/// Get sh coefficient indexed by i.
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float elemAt( int i ) const {
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return m_elemArray[i];
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}
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/// Get sh coefficient indexed by i.
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float & elemAt( int i )
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{
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return m_elemArray[i];
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}
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/// Reset the sh coefficients.
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void reset()
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{
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for( int i = 0; i < basisNum(); i++ ) {
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m_elemArray[i] = 0.0f;
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}
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}
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/// Copy spherical harmonic.
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void operator= ( const Sh & sh )
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{
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nvDebugCheck(order() <= sh.order());
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for(int i = 0; i < basisNum(); i++) {
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m_elemArray[i] = sh.m_elemArray[i];
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}
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}
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/// Add spherical harmonics.
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void operator+= ( const Sh & sh )
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{
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nvDebugCheck(order() == sh.order());
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for(int i = 0; i < basisNum(); i++) {
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m_elemArray[i] += sh.m_elemArray[i];
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}
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}
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/// Substract spherical harmonics.
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void operator-= ( const Sh & sh )
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{
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nvDebugCheck(order() == sh.order());
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for(int i = 0; i < basisNum(); i++) {
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m_elemArray[i] -= sh.m_elemArray[i];
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}
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}
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// Not exactly convolution, nor product.
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void operator*= ( const Sh & sh )
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{
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nvDebugCheck(order() == sh.order());
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for(int i = 0; i < basisNum(); i++) {
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m_elemArray[i] *= sh.m_elemArray[i];
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}
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}
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/// Scale spherical harmonics.
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void operator*= ( float f )
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{
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for(int i = 0; i < basisNum(); i++) {
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m_elemArray[i] *= f;
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}
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}
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/// Add scaled spherical harmonics.
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void addScaled( const Sh & sh, float f )
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{
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nvDebugCheck(order() == sh.order());
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for(int i = 0; i < basisNum(); i++) {
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m_elemArray[i] += sh.m_elemArray[i] * f;
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}
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}
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/*/// Add a weighted sample to the sh coefficients.
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void AddSample( const Vec3 & dir, const Color3f & color, float w=1.0f ) {
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for(int l = 0; l <= order; l++) {
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for(int m = -l; m <= l; m++) {
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Color3f & elem = GetElem(l, m);
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elem.Mad( elem, color, w * shBasis(l, m, dir) );
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}
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}
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}*/
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/// Evaluate
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void eval(Vector3::Arg dir)
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{
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for(int l = 0; l <= m_order; l++) {
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for(int m = -l; m <= l; m++) {
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elem(l, m) = shBasis(l, m, dir);
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}
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}
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}
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/// Evaluate the spherical harmonic function.
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float sample(Vector3::Arg dir) const
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{
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Sh sh(order());
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sh.eval(dir);
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return dot(sh, *this);
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}
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protected:
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const int m_order;
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float * m_elemArray;
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};
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/// Compute dot product of the spherical harmonics.
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inline float dot(const Sh & a, const Sh & b)
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{
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nvDebugCheck(a.order() == b.order());
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float sum = 0;
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for( int i = 0; i < Sh::basisNum(a.order()); i++ ) {
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sum += a.elemAt(i) * b.elemAt(i);
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}
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return sum;
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}
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/// Second order spherical harmonic.
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class Sh2 : public Sh
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{
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public:
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/// Constructor.
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Sh2() : Sh(2) {}
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/// Copy constructor.
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Sh2(const Sh2 & sh) : Sh(sh) {}
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/// Spherical harmonic resulting from projecting the clamped cosine transfer function to the SH basis.
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void cosineTransfer()
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{
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const float c1 = 0.282095f; // K(0, 0)
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const float c2 = 0.488603f; // K(1, 0)
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const float c3 = 1.092548f; // sqrt(15.0f / PI) / 2.0f = K(2, -2)
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const float c4 = 0.315392f; // sqrt(5.0f / PI) / 4.0f) = K(2, 0)
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const float c5 = 0.546274f; // sqrt(15.0f / PI) / 4.0f) = K(2, 2)
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const float normalization = PI * 16.0f / 17.0f;
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const float const1 = c1 * normalization * 1.0f;
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const float const2 = c2 * normalization * (2.0f / 3.0f);
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const float const3 = c3 * normalization * (1.0f / 4.0f);
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const float const4 = c4 * normalization * (1.0f / 4.0f);
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const float const5 = c5 * normalization * (1.0f / 4.0f);
|
||||
|
||||
m_elemArray[0] = const1;
|
||||
|
||||
m_elemArray[1] = -const2;
|
||||
m_elemArray[2] = const2;
|
||||
m_elemArray[3] = -const2;
|
||||
|
||||
m_elemArray[4] = const3;
|
||||
m_elemArray[5] = -const3;
|
||||
m_elemArray[6] = const4;
|
||||
m_elemArray[7] = -const3;
|
||||
m_elemArray[8] = const5;
|
||||
}
|
||||
};
|
||||
|
||||
|
||||
|
||||
/// Spherical harmonic matrix.
|
||||
class ShMatrix
|
||||
{
|
||||
public:
|
||||
|
||||
/// Create an identity matrix of the given order.
|
||||
ShMatrix(int o = 2) : m_order(o), m_identity(true)
|
||||
{
|
||||
nvCheck(m_order > 0);
|
||||
m_e = new float[size()];
|
||||
m_band = new float *[bandNum()];
|
||||
setupBands();
|
||||
}
|
||||
|
||||
/// Destroy and free matrix elements.
|
||||
~ShMatrix()
|
||||
{
|
||||
delete m_e;
|
||||
delete m_band;
|
||||
}
|
||||
|
||||
/// Set identity matrix.
|
||||
void setIdentity()
|
||||
{
|
||||
m_identity = true;
|
||||
}
|
||||
|
||||
/// Return true if this is an identity matrix, false in other case.
|
||||
bool isIdentity() const {
|
||||
return m_identity;
|
||||
}
|
||||
|
||||
/// Get number of bands of this matrix.
|
||||
int bandNum() const
|
||||
{
|
||||
return m_order+1;
|
||||
}
|
||||
|
||||
/// Get total number of elements in the matrix.
|
||||
int size() const
|
||||
{
|
||||
int size = 0;
|
||||
for (int i = 0; i < bandNum(); i++) {
|
||||
size += square(i * 2 + 1);
|
||||
}
|
||||
return size;
|
||||
}
|
||||
|
||||
/// Get element at the given raw index.
|
||||
float element(int idx) const
|
||||
{
|
||||
return m_e[idx];
|
||||
}
|
||||
|
||||
/// Get element at the given with the given indices.
|
||||
float & element(int b, int x, int y)
|
||||
{
|
||||
nvDebugCheck(b >= 0);
|
||||
nvDebugCheck(b < bandNum());
|
||||
return m_band[b][(b + y) * (b * 2 + 1) + (b + x)];
|
||||
}
|
||||
|
||||
/// Get element at the given with the given indices.
|
||||
float element(int b, int x, int y) const
|
||||
{
|
||||
nvDebugCheck(b >= 0);
|
||||
nvDebugCheck(b < bandNum());
|
||||
return m_band[b][(b + y) * (b * 2 + 1) + (b + x)];
|
||||
}
|
||||
|
||||
/// Copy matrix.
|
||||
void copy(const ShMatrix & m)
|
||||
{
|
||||
nvDebugCheck(m_order == m.m_order);
|
||||
memcpy(m_e, m.m_e, size() * sizeof(float));
|
||||
}
|
||||
|
||||
/// Rotate the given coefficients.
|
||||
/*void transform( const Sh & restrict source, Sh * restrict dest ) const {
|
||||
nvCheck( &source != dest ); // Make sure there's no aliasing.
|
||||
nvCheck( dest->m_order <= m_order );
|
||||
nvCheck( m_order <= source.m_order );
|
||||
|
||||
if (m_identity) {
|
||||
*dest = source;
|
||||
return;
|
||||
}
|
||||
|
||||
// Loop through each band.
|
||||
for (int l = 0; l <= dest->m_order; l++) {
|
||||
|
||||
for (int mo = -l; mo <= l; mo++) {
|
||||
|
||||
Color3f rgb = Color3f::Black;
|
||||
|
||||
for( int mi = -l; mi <= l; mi++ ) {
|
||||
rgb.Mad( rgb, source.elem(l, mi), elem(l, mo, mi) );
|
||||
}
|
||||
|
||||
dest->elem(l, mo) = rgb;
|
||||
}
|
||||
}
|
||||
}*/
|
||||
|
||||
|
||||
NVMATH_API void multiply( const ShMatrix &A, const ShMatrix &B );
|
||||
NVMATH_API void rotation( const Matrix & m );
|
||||
NVMATH_API void rotation( int axis, float angles );
|
||||
NVMATH_API void print();
|
||||
|
||||
|
||||
private:
|
||||
|
||||
// @@ These could be static indices precomputed only once.
|
||||
/// Setup the band pointers.
|
||||
void setupBands()
|
||||
{
|
||||
int size = 0;
|
||||
for( int i = 0; i < bandNum(); i++ ) {
|
||||
m_band[i] = &m_e[size];
|
||||
size += square(i * 2 + 1);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
private:
|
||||
|
||||
// Matrix order.
|
||||
const int m_order;
|
||||
|
||||
// Identity flag for quick transform.
|
||||
bool m_identity;
|
||||
|
||||
// Array of elements.
|
||||
float * m_e;
|
||||
|
||||
// Band pointers.
|
||||
float ** m_band;
|
||||
|
||||
};
|
||||
|
||||
|
||||
} // nv namespace
|
||||
|
||||
#endif // NV_MATH_SPHERICALHARMONIC_H
|
Loading…
Reference in New Issue