Define up to nine lines of expressions at the Script panel. Verify that you compute the ox and oy variables at least once, they contain the coordinates of the new pixel. The coordinates of the calculated pixel is stored in the x and y values.

For example the script
ox=x*2
oy=y*2
makes the texture tile 2x2 on its old surface.

You can limit the function's effect to horizontal and vertical direction only.

Utilize the direction vector in the script, which is stored in the DirAngle and DirRadius variables.

The Amplify value can be used as variable amp in the script.