Math - Graphics 3D: where is Z?

[joaquim]

ok... the screen have only X,Y... easy working with them.
now imagine that X, Y and Z angles are zero.
the coordinates are (10,20,30).
i know where is (10,20)(X, Y)... but how can i add the Z?
(ok... i'm trying learn 3D coordinates on hard way... but it's for learn)

[Guest]

I'm not sure I understand your question correctly, but if X is left/right, Y is up/down, then Z is in/out. So if 3D screens existed, the Z axis would point out of the screen into your face. (Whether positive values point toward or away from you depends on the graphics framework used)

Since screens are 2D, the third dimension has to be faked by adjusting the X/Y dimensions. This is usually done using a projection transform. A good analogy are railroad tracks. The real tracks remain the same distance apart, but in a 2D photograph they converge into a point in the distance. So the X/Y axes are used to give the impression of the missing Z axis (distance).

[joaquim]

i'm sorry Adrian, but by some reason i don't receive a mail notification
thanks for correct me