There seems to be general difficulty in determining when you have a
completely correct perspective result.  I've just added 4 specific cube
views on the web page that you should be able to exactly reproduce if you
have a 100% perfect result.  If you get exactly those results then your
perspective will "almost certainly" (leaving my self a little wiggle room
for some error mode I don't yet imagine) be correct for all other
views and for the different object.

Note the behavior of certain things that I pointed out in class but whose
significance may not have been clear until you actually got into the work.
Assuming a non rotated view...
1. No matter where you drag the cursor the green mid layer and the P
remain fixed on the screen.
2. Similarly as you move in and out with the 'i' and 'o' keys the green
band and P remain stationary.
3. If you move the cursor left, the front of the cube goes right.
  (same idea up and down etc.)
4. If you move in to eyez == 6 then no matter where you drag the cursor
the back face of the cube will always be half as wide and tall as the front.
5. If you look down along a corner or edge then all the points at that
3D edge will pile up (ie. foreshorten) into a 2D edge.

These are the most important cases I use to quickly test your programs.
These are what the 4 new web page cube views show.

-Art