I am learning the basics of geometry shaders and I came across references to the "Z plane." It's pretty easy to visualize the X and Y planes, but where does the Z plane reside in Cartesian space? Wikipedia says

it can be thought of as a modified Cartesian plane

So how exactly am I going to visualize it? Looking at google images doesn't help either. I am not a math savvy person so can someone help me understand the Z plane better?


1 Answer 1


You can think that z-plane is like a book glued to your monitor screen . You look at it, and each z-coord represents a page ( which then, have their x,y-coords ).

Also, maybe those three images will help you a little:

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  • \$\begingroup\$ I must be overthinking this a bit. Such a simple matter confuses me a lot. Thanks. \$\endgroup\$
    – thenewbie
    Commented Jan 13, 2016 at 14:23
  • 1
    \$\begingroup\$ @thenewbie Z is effectively the axis that runs perpendicular to the screen, which actually explains why X/Z is typically the ground in 3D engines, with Y being up. This tends to cause some confusion as we more natively think about the ground itself being X and Y (e.g. longitude and latitude). Additionally, there are also some other uses of "Z" in 3D programming, such as depth sorting. It's still a Z-axis, but its one that is always perpendicular to the physical screen, irrespective of the 3D environment's Z-axis, which is where the term Z-Fighting comes from. \$\endgroup\$ Commented Jan 13, 2016 at 15:25
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    \$\begingroup\$ Um the right hand thing depends on the coordinate system. Might be left handed. \$\endgroup\$
    – Almo
    Commented Jan 19, 2016 at 16:46

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