Re: Custom Core Image filter help

FROM : Nicko van Someren
DATE : Thu Feb 21 23:08:40 2008

On 20 Feb 2008, at 18:07, Daniel Thorpe wrote:

> Hey Nicko, thanks for getting back to me...


No problem!

> I am having some problems with my kernel code however, which I've 
> changed as you suggested (I had already done this in my Obj-C 
> implementation)...
>
> This is my kernel code:

...
>     const float N = %.1lf;


I'd be inclined to make this an integer, since it will be easier for 
the compiler to deal optimise it out.

>         for(x=0.0; x<N; x++) {

...
>         }


You should be able to replace this with a call to dot(), if you set 
your Tchebichef image up correctly.

> Unfortunately, this doesn't seem to work yet, as it crashed 
> QuartzComposer instantly (as in as soon as I type in the kernel 
> stuff with a suitable N. Which leads me to think, that it's 
> syntactically correct, but essentially wrong....


That's odd, though I've managed to write kernel code that would crash 
my machine in the (distant) past.

> So... have you got any other thoughts?


Making 'N' an integer might help the compiler.  Other than that I 
don't have any ideas just now :-(

   Cheers,
       Nicko