Isometric view: Solution?

It occurred to me that, if normally the square on which the texture is drawn can't be transformed properly, why couldn't I simply make a primitive?

So I'll research using primitives for my isometric view now.
Here's what I understand so far:

(Fixed as of May 27.)

Notice the 2 triangles (ABD) and (BCD) the primitive gets split up in.
This way it is easy for the computer to draw the shapes.

Now I can have my texture:

And map the texture to the primitive as follows:
(WA), (XB), (YC), (ZD)

Can you imagine a field full of those?
This is how it looks:

Not bad at all. The texture is a bit blurred, but I will scale it down in the final game instead of making it larger, which will reduce the blur but hopefully retain the feel of the texture.

But all we have now is still a grassy plain, without any hills whatsoever - I'll have to add an extra dimension to my array soon, and recalculate the drawing height. Wish me luck.