# What is the near plane equation in NDC?

I'm trying to compute the line intersecting my plane (transformed to NDC) and the near plane.
I have troubles to get a correct result and I think it is coming from the near plane equation.

I suppose that the equation in normalized device coordinates is $N=(0,0,1)$ and $O=(0,0,near)$.
But what is the value of $near$? Is it constant or it depends on the frustum?

• doesn't it go from -1 to 1? I thought NDC is a box that goes from -1 to 1 on all axis – Sidar Jan 23 '18 at 14:08
• @Sidar, yes you're right. I managed to fix my issue, thanks. The equation of near plane in NDC is $z+1=0$ – Michael M. Jan 23 '18 at 15:44
• might want to post the answer then =P – Sidar Jan 23 '18 at 15:59

Near plane equation is therefore $Z+1=0$ and far plane $Z-1=0$