The Swirlomatic is a pixelwise kernel which does random access on its single input. It warps a circular area of the input image around in a swirl.
Change the Amount parameter to vary the tightness of the swirl. You can also change the Size of the swirl and the position of its Centre.
// Copyright (c) 2012 The Foundry Visionmongers Ltd. All Rights Reserved.
// Example RIP Kernel
/// SwirlomaticKernel: does a nice swirl. Amount is in degrees.
kernel Swirlomatic : ImageComputationKernel<ePixelWise> {
Image<eRead, eAccessRandom, eEdgeClamped> src;
Image<eWrite, eAccessPoint> dst;
param:
float amount;
int size;
float2 centre;
local:
float _sizeInv;
float _cs, _sn;
void define() {
defineParam(amount, "Amount", 180.0f);
defineParam(size, "Size", 640);
defineParam(centre, "Centre", float2(640.0f, 360.0f));
}
void init() {
_sizeInv = size <= 0 ? 0 : 1.0f/size;
_sizeInv *= _sizeInv;
}
void process(int2 pos) {
float dx = float(pos.x) - centre.x;
float dy = float(pos.y) - centre.y;
float delta = 1.0f - ((dx*dx + dy*dy) * _sizeInv);
if (delta < 0) delta = 0;
float cs = cos(delta * amount * 3.1415926535f/180.0f);
float sn = sin(delta * amount * 3.1415926535f/180.0f);
float x = centre.x + dx * cs + dy * sn;
float y = centre.y - dx * sn + dy * cs;
for (int c = 0; c < dst.kComps; c++)
dst(c) = bilinear(src, x, y, c);
}
};