Making diagonal textures?

[MushyMushy 3,617]

I've been messing around with making some path-type textures, and all has gone well with making the ortho pieces and the curves (thanks to the Texture Bender rivit made), but I haven't been able to make diagonal (or FA) straight pieces at all. They never seem to line up properly when I put multiple ones I made next to each other. I'm trying to make them the same way all of the Maxis and NAM diagonal transit textures are made - in a sort of stair step fashion. Is there some simple way to make a diagonal version of a texture like this? A program or just a technique in a photo editor? I have a old Photoshop which I'm pretty familiar with and I just downloaded GIMP yesterday, so I have those to work with.

[Tarkus 6,931]

A little trigonometry can be used to your advantage for diagonals and FA. 

The following formula can help: 100 * (sin(x) + cos(x)), where x is the angle of the network (it'd be 45° for diagonals, 18.4° for FA-3, and 26.6° for FA-2).  That'll give you a scaling adjustment.  The results, just to help you skip along a step, end up being 141.42% for diagonals, 126.45% for FA-3, and 134.19% for FA-2.  Assuming your orthogonal piece is running north-south, you'll want to repeat the orthogonal texture out to a file tiles worth of length, then upscale the width by the scaling factor, then skew the texture by the negative version of the angle (i.e. -45° for diagonal), and it'll end up about what a normal Maxis or NAM diagonal would look like.  You'll probably have to do some horizontal manipulation as well to get it to align properly.  I'll post some more details on that in a bit, but that should (hopefully) get you started.

-Tarkus