Pixel Bender Toolkit:Polar filter
From Adobe Labs
(Redirected from AIF Toolkit:Polar filter)
// Image Dimension Requirement: 256x256 kernel Polar {
parameter bool cartesian_to_polar;
parameter float radius
<
minValue: float(0.0);
maxValue: float(256.0);
defaultValue: float(128.0);
>;
parameter float2 center
<
minValue: float2(0.0, 0.0);
maxValue: float2(256.0, 256.0);
defaultValue: float2(128.0, 128.0);
>;
void evaluatePixel(in image4 src, out pixel4 dst)
{
float2 coord = outCoord();
float2 p = coord-center; // point
float d = length(p); // length
float w = radius*2.0; // width
float h = radius*2.0; // height
if(!cartesian_to_polar){
float theta = atan(p.y/p.x); // angle
if(coord.x < radius) theta += 3.14;
float degrees = degrees(theta) + 90.0;
float dx = w - (degrees*w/360.0);
float dy = (d*h/radius);
coord.x = (dx>=w) ? w-1.0:dx;
coord.y = (dy>=h) ? h-1.0:dy;
}else{
float polardegrees = 90.0 - (coord.x + w)/w*360.0;
float polard = coord.y*radius/h;
float polartheta = radians(polardegrees);
float polarx = center.x - polard*cos(polartheta);
float polary = center.y - polard*sin(polartheta);
coord.x = polarx;
coord.y = polary;
}
dst = sampleNearest(src, coord);
}
}
