Question on D in plane equation

[YanhaoZhang]

Hi, Thanks a lot for this interesting work. I am reading the code and have a quick question about the calculation of D in $Ax+By+Cz+D=0$. From the equation, $n_r=[A,B,C]$ and $D=d_r n_r \cdot v$

However, from the code

A = nm[:,0].unsqueeze(-1)
B = nm[:,1].unsqueeze(-1)
C = nm[:,2].unsqueeze(-1)
C = -torch.sigmoid(C)
z_vals_p0 = dm[:,0].unsqueeze(-1)
D = -z_vals_p0*C

It seems to be $D=-d_r \sigma(C)$. May I ask for some explanation? Thanks a lot.