# Calculate equivalent (X,Y) given (X,Y,Z)

I'm working on generating a 3D-looking application (in 2D) and am having difficulty generating my graphing points equally. I can only graph in 2D, but want to have a 3D look to it (similar to a FPS-style game).

My question: If I have a 3-dimension point $(X, Y, Z)$, what formula should I use to calculate the adjusted $(X, Y)$ points given my current point of view?

Example: Say I have a point $(-5, 5, 5)$. This would lie in the second quadrant of a standard graph, but if my view is at $(0, 0, 0)$, the point should not appear right at $(-5, 5)$ [in 2D], but slightly lower, and to the right a bit. How do I calculate where this point is located at in terms of $(X, Y)$?

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There are, of course, libraries that do the work for you.... – Hurkyl Apr 9 '12 at 3:05