Finally got around to adding those few lines of code to add textured walls to the ray caster.
A few details:
The texture isn't mine, I merely found it via Google Images with the term "wall texture" and it has the filename
There's still a problem with the corners of the grids having a weird fringe. It's better than it was, but still not right. Haven't tracked that down yet, but have some ideas
The somewhat hybrid mix (Courtesy of XNA) of performing the ray casting algorithm and then using the hardware to render (i.e. the column strips as Lines, plus using the hardware to render the correct strip of texture, which is all nice and filtered) is arguably making using the ray caster seem futile. Depends on how you look at that one I suppose. I think it's neat
A bit of "FYI". John Carmack's article on how he wrote the iPhone version of Wolfenstein 3D is what really got me wanting to do this. Many thanks to him for the unrelenting inspiration!