Let's say I have two triangles in a 3D space

The triangles are, of course, made from 3 coordinates (each coordinate an X/Y/Z set)

First Triangle:

X1 = 0, Y1 = 0, Z1 = Dynamic

X2 = 1, Y2 = 0, Z2 = Dynamic

X3 = 1, Y3 = 1, Z3 = Dynamic

Second Triangle:

X1 = 0, Y1 = 0, Z1 = Dynamic

X2 = 1, Y2 = 1, Z2 = Dynamic

X3 = 1, Y3 = 0, Z3 = Dynamic

... So, basically, a square that's cut through the middle (and bends on that cut)

Each Z value for each is known, but varies from instance to instance. And they vary independently.

If I have a position (Say, X=0.13,Y=0.73)

How would I calculcate what the Z of the triangle will be at that position?

(I'm hoping for an equation or pseudocode that will calculate the value without using raytracing or any expensive functions like that)

**Edited by mcmonkey, 20 February 2013 - 06:07 PM.**