void Alaska::calculate_ho()
{
double horizontal[2];
double root_of_phillips;
double gauss_value[2];// this is where gauss generator returns two random values
for (int i=0;i<NX;i++)
{
for (int j=0;j<NY;j++)
{
// hold_horizontal saves these fixed calculations for later use:k[2],klen,klen*klen
horizontal[0]=hold_horizontal[i][j][0]=2.0*PI*((double)i-.5*NX)/MAX_WORLD_X;// center the origin
horizontal[1]=hold_horizontal[i][j][1]=2.0*PI*((double)j-.5*NX)/MAX_WORLD_Y;// center the origin
hold_horizontal[i][j][3]=hold_horizontal[i][j][0]*hold_horizontal[i][j][0]+hold_horizontal[i][j][1]*hold_horizontal[i][j][1];
hold_horizontal[i][j][2]=sqrt(hold_horizontal[i][j][3]);
// horizontal[0]=hold_horizontal[i][j][0]=2.0*PI*((float)i-.5*NX)/MAX_WORLD_X;
// horizontal[1]=hold_horizontal[i][j][1]=2.0*PI*((float)j-.5*NX)/MAX_WORLD_Y;
gauss(gauss_value);
root_of_phillips=sqrt(phillips(a_global,horizontal,wind_global));
mH0[i][j].real=INV_SQRT_TWO*gauss_value[0]*root_of_phillips;
mH0[i][j].imag=INV_SQRT_TWO*gauss_value[1]*root_of_phillips;
}
}
}
// Generate base heightfield in frequency space
void generate_h0()
{
for (unsigned int y = 0; y<fftInputH; y++) {
for (unsigned int x = 0; x<fftInputW; x++) {
float kx = CUDART_PI_F * x / (float) patchSize;
float ky = 2.0f * CUDART_PI_F * y / (float) patchSize;
// note - these random numbers should be from a Gaussian distribution really
float Er = 2.0f * rand() / (float) RAND_MAX - 1.0f;
float Ei = 2.0f * rand() / (float) RAND_MAX - 1.0f;
float P = sqrt(phillips(kx, ky, windDir, windSpeed, A));
float h0_re = 1.0f / sqrtf(2.0f) * Er * P;
float h0_im = 1.0f / sqrtf(2.0f) * Ei * P;
int i = y*fftInputW+x;
h_h0[i].x = h0_re;
h_h0[i].y = h0_im;
}
}
}
GLFFTWater::GLFFTWater(GLFFTWaterParams ¶ms) {
#ifdef _WIN32
m_h = (float *)__mingw_aligned_malloc((sizeof(float)*(params.N+2)*(params.N)), 4);
m_dx = (float *)__mingw_aligned_malloc((sizeof(float)*(params.N+2)*(params.N)), 4);
m_dz = (float *)__mingw_aligned_malloc((sizeof(float)*(params.N+2)*(params.N)), 4);
m_w = (float *)__mingw_aligned_malloc((sizeof(float)*(params.N)*(params.N)), 4);
#else
posix_memalign((void **)&m_h,4,sizeof(float)*(params.N+2)*(params.N));
posix_memalign((void **)&m_dx,4,sizeof(float)*(params.N+2)*(params.N));
posix_memalign((void **)&m_dz,4,sizeof(float)*(params.N+2)*(params.N));
posix_memalign((void **)&m_w,4,sizeof(float)*(params.N)*(params.N));
#endif
m_htilde0 = (fftwf_complex *)fftwf_malloc(sizeof(fftwf_complex)*(params.N)*(params.N));
m_heightmap = new float3[(params.N)*(params.N)];
m_params = params;
std::tr1::mt19937 prng(1337);
std::tr1::normal_distribution<float> normal;
std::tr1::uniform_real<float> uniform;
std::tr1::variate_generator<std::tr1::mt19937, std::tr1::normal_distribution<float> > randn(prng,normal);
std::tr1::variate_generator<std::tr1::mt19937, std::tr1::uniform_real<float> > randu(prng,uniform);
for(int i=0, k=0; i<params.N; i++) {
float k_x = (-(params.N-1)*0.5f+i)*(2.f*3.141592654f / params.L);
for(int j=0; j<params.N; j++, k++) {
float k_y = (-(params.N-1)*0.5f+j)*(2.f*3.141592654f / params.L);
float A = randn();
float theta = randu()*2.f*3.141592654f;
float P = (k_x==0.f && k_y==0.0f) ? 0.f : sqrtf(phillips(k_x,k_y,m_w[k]));
m_htilde0[k][0] = m_htilde0[k][1] = P*A*sinf(theta);
}
}
m_kz = new float[params.N*(params.N / 2 + 1)];
m_kx = new float[params.N*(params.N / 2 + 1)];
const int hN = m_params.N / 2;
for(int y=0; y<m_params.N; y++) {
float kz = (float) (y - hN);
for(int x=0; x<=hN; x++) {
float kx = (float) (x - hN);
float k = 1.f/sqrtf(kx*kx+kz*kz);
m_kz[y*(hN+1)+x] = kz*k;
m_kx[y*(hN+1)+x] = kx*k;
}
}
if(!fftwf_init_threads()) {
cerr << "Error initializing multithreaded fft." << endl;
} else {
fftwf_plan_with_nthreads(2);
}
m_fftplan = fftwf_plan_dft_c2r_2d(m_params.N, m_params.N, (fftwf_complex *)m_h, m_h,
FFTW_ESTIMATE);
glGenTextures(1, &m_texId);
glBindTexture(GL_TEXTURE_2D, m_texId);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, params.N, params.N, 0, GL_RGB, GL_FLOAT, 0);
glBindTexture(GL_TEXTURE_2D, 0);
}