Mailing Lists: Apple Mailing Lists
Image of Mac OS face in stamp
 
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Linear image

Hi,

note that the kernel code below has a bug, in that the sampler transform is applied twice. This will fail in interesting ways if the sampler transform is not identity (when Core Image tiles the evaluation for example).

A different implementation could look like this:

kernel vec4 linearImage(sampler image, float y)
{
     vec2 xy = vec2(destCoord().x, y);

     return sample(image, samplerTransform(image, xy));
}

- Ralph


--- Sam Kass <email@hidden> wrote: 
Core Image kernel functions are called once for each
output pixel.
If I understand LinearImage, it's picking one raster
(y value) out of
the image and displaying that for the whole image?
If so, then for
each output pixel, you want to return the pixel that
is in the same
column, but a specified row.  To duplicate what's on
the web site,
try something like the following, and hook it up to
a mouse input
(I'm coding in my email client, so there may be
bugs):

kernel vec4 linearImage(sampler image, float ycoord)
{
     // get xy value
     vec2 xy = samplerCoord(image);
     // return image pixels for our column,
specified row
     return sample(image, samplerTransform(image,
vec2(xy.x, ycoord)));
}

_______________________________________________
Do not post admin requests to the list. They will be ignored.
Quartzcomposer-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quartzcomposer-dev/email@hidden

This email sent to email@hidden


Visit the Apple Store online or at retail locations.
1-800-MY-APPLE

Contact Apple | Terms of Use | Privacy Policy

Copyright © 2007 Apple Inc. All rights reserved.