Tilted circle in 3D mesh

I have 3D mesh set and I want to give semicurcular region a differnet value. I have done this for vertical semi circle (as shown in figure) but how to do it for tilted semi circle. the code for generating vertical semi circle is here.

dx=1e-4;
R= 4e-3*dx;
for x = 1:500
    for y=1:500
        for z= 1:500
            model(x,y,z) = 6300;
            if z>=(x-250).^2 + (z-500).^2 - R.^2 && y==250
                model(x,y,z) = 300;
            end
        end
    end
end

Answer 1

[Nikhil Sonavane]

You may to refer an already existing answer in MATLAB Answers in this regard.