There was also a little code snippet to handle texture transparency.

			.
			.
			.
	int pix = texture.getPixel(uval, vval);
	if ((pix & 0xff000000) != 0) {
	    raster.pixel[y+x] = pix;
	    raster.zbuff[y+x] = iz;
	}
			.
			.
			.

Now you can all go out and write DOOM!