I have followed a tutorial to make a directional kuwahara filter. But rather than the kuwuhara filter to apply as a post process, I want it to apply it specific objects, i.e. apply the filter to 2D textures.
This is the code that I followed:
float3 mean[4] = {
{0,0,0},
{0,0,0},
{0,0,0},
{0,0,0}
};
float3 sigma[4] = {
{0,0,0},
{0,0,0},
{0,0,0},
{0,0,0}
};
float2 offsets[4] = {{-RADIUS.x, -RADIUS.y}, {-RADIUS.x,0}, {0,-RADIUS.y}, {0,0}};
float2 pos;
float3 col;
float gradientX = 0;
float gradientY = 0;
float sobelX[9] = {-1, -2, -1, 0, 0, 0, 1, 2, 1};
float sobelY[9] = {-1, 0, 1, -2, 0, 2, -1, 0, 1};
int index = 0;
float2 texelSize = 1.0/VIEWSIZE;
for(int x = -1; x <= 1; x++)
{
for(int y = -1; y <= 1; y++)
{
if(index == 4)
{
index++;
continue;
}
float2 offset = float2(x, y) * texelSize;
float3 pxCol = (UV + offset, 14, false).xyz;
float pxLum = dot(pxCol, float3(0.2126, 0.7152, 0.0722));
gradientX += pxLum * sobelX[index];
gradientY += pxLum * sobelY[index];
index++;
}
}
float angle = 0;
if(abs(gradientX) > 0.001)
{
angle = atan(gradientY/gradientX);
}
float s = sin(angle);
float c = cos (angle);
for(int i=0; i<4;i++)
{
for(int j=0; j<=RADIUS.x;j++)
{
for(int k=0; k<=RADIUS.y; k++)
{
pos = float2 (j,k) + offsets[i];
float2 offs = pos * texelSize;
offs = float2(offs.x * c - offs.y * s, offs.x * s + offs.y * c);
float2 uvpos = UV + offs;
col = SceneTextureLookup(uvpos, 14, false);
mean[i] += col;
sigma[i] += col * col;
}
}
}
float n = (RADIUS.x+1)*(RADIUS.y+1);
float sigma_f;
float min = 1;
for(int i=0; i<4; i++)
{
mean[i] /= n;
sigma [i] = abs(sigma[i]/n - mean[i] * mean [i]);
sigma_f = sigma[i].r + sigma[i].g + sigma[i].b;
if(sigma_f < min)
{
min = sigma_f;
col = mean[i];
}
}
return col;
