getIFFT

//This algorithm includes auto shift so that the input data is gathered on center 

float getIFFT(float2 UV, float targetTextureSize)

{

float targetTexSize = targetTextureSize;

float2 Tex_xy = floor(UV * (targetTexSize - 1)); //transform to integer. 

float M = 13; //Only right square texture, preserved data size

float result = 0;

for (float u = 0; u < 13; ++u)

{

for (float v = 0; v < 13; ++v)

{

//float4 tx = microTX.SampleLevel(g_samLinear, float2(u / M, v / M), 0);

float a = MICRO_REAL[u][v];

float b = MICRO_IMAG[u][v];

//float u_ = (((targetTextureSize - 1.0f) / 2.0f - (M - 1.0f) / 2.0f) + u + (targetTextureSize + 1.0f) / 2.0f) % targetTextureSize;

//float v_ = (((targetTextureSize - 1.0f) / 2.0f - (M - 1.0f) / 2.0f) + v + (targetTextureSize + 1.0f) / 2.0f) % targetTextureSize;

float u_ = (507 + u) % 513;

float v_ = (507 + v) % 513;

float theta = 2 * IAN_PI *(Tex_xy.x * u_ / targetTexSize + Tex_xy.y * v_ / targetTexSize);

result += (a*cos(theta) - b*sin(theta));

}

}

result = result / targetTexSize / targetTexSize;

return result;

}