[Liboil] 2D convolution with Orc

[jcupitt at gmail.com]

Hi all,

I've been tinkering with Orc trying to make a 2D convolution. It seems
to me that I'll need to use loadoffb to get the scattered pixel values
from my source array, but the 'off' part needs to be a parameter or
constant. This means (I think) that I need to pass in the offset for
every array element as a separate parameter.

This wouldn't be too bad for a 3x3 I guess, but for larger matrices I
wonder if this will start to be rather slow. Is there a way to
calculate the offset in my Orc code instead? Or perhaps I'm missing a
much better way to do this.

John