WKDisplacementMapFilter.cikernel [plain text]
/*
* Copyright (C) 2006 Oliver Hunt <ojh16@student.canterbury.ac.nz>. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Performs the transformation:
* P'(x,y) <- P( x + scale * (XC(x,y) - .5), y + scale * (YC(x,y) - .5))
*
* x/ychannel arguments are used to select the appropriate channel for x and
* y displacement. Hence each vector should have only one non-zero element,
* which should have the value 1.0.
*
*/
kernel vec4 displacementMap(sampler image, sampler map, vec4 xchannel, vec4 ychannel, float scale)
{
vec2 samplePos = samplerCoord(image);
vec4 XCYC = sample(map, samplerCoord(map));
float xc = dot(XCYC, xchannel);
float yc = dot(XCYC, ychannel);
samplePos.x += scale*(xc-0.5);
//flip the y-axis
samplePos.y -= scale*(yc-0.5);
return sample(image, samplePos);
}