imageData = new double*[imageHeight];
for(int i = 0; i < imageHeight; i++) {
imageData[i] = new double[imageWidth];
for(int j = 0; j < imageWidth; j++) {
// compute the distance and angle from the swirl center:
double pixelX = (double)i - swirlCenterX;
double pixelY = (double)j - swirlCenterY;
double pixelDistance = pow(pow(pixelX, 2) + pow(pixelY, 2), 0.5);
double pixelAngle = atan2(pixelX, pixelY);
// double swirlAmount = 1.0 - (pixelDistance/swirlRadius);
// if(swirlAmount > 0.0) {
// double twistAngle = swirlTwists * swirlAmount * PI * 2.0;
double twistAngle = swirlTwists * pixelDistance * PI * 2.0;
// adjust the pixel angle and compute the adjusted pixel co-ordinates:
pixelAngle += twistAngle;
pixelX = cos(pixelAngle) * pixelDistance;
pixelY = sin(pixelAngle) * pixelDistance;
// }
(this)->setPixel(i, j, tempMatrix[(int)(swirlCenterX + pixelX)][(int)(swirlCenterY + pixelY)]);
}
}
I am trying to implement a c++ function (code above) based on the following pseudo-code which is supposed to create a swirl on an image, but I have some continuity problems on the borders.
The function I have for the moment is able to apply the swirl on a disk of a given size and to deform it almost as I whished but its influence doesn't decrease as we get close to the borders. I tried to multiply the angle of rotation by a 1 - (r/R) factor (with r the distance between the current pixel in the function and the center of the swirl, and R the radius of the swirl), but this doesn't give the effect I hoped for.
Moreover, I noticed that at some parts of the border, a thin white line appears (which means that the values of the pixels there is equal to 1) and I can't exactly explain why.
Maybe some of the problems I have are linked to the atan2 C++ standard function.
