Help with a visual effect

[SkripT]

Hi again, I attach the code that I use, trying as wysota comments. The problem is that the rotation is done in 2D, so if I try to rotate an image 90º from the Y axis, the result is not a vertical line or even a null image

#include <QtGui>
#include <math.h>
 
 
int main(int argc, char *argv[])
{
    	QApplication a(argc, argv);
 
	QImage imatge("../test.jpg");
 
        double radians = 90 * 3.14159265 / 180;  //rotation of 90º
 
	imatge = imatge.transformed(QMatrix(cos(radians),-sin(radians),sin(radians),cos(radians),0,0));
        imatge.save("../transformated.jpg", "jpg");
 
	return 0;
}

#include <QtGui>
#include <math.h>
 

int main(int argc, char *argv[])
{
    	QApplication a(argc, argv);

	QImage imatge("../test.jpg");

        double radians = 90 * 3.14159265 / 180;  //rotation of 90º

	imatge = imatge.transformed(QMatrix(cos(radians),-sin(radians),sin(radians),cos(radians),0,0));
        imatge.save("../transformated.jpg", "jpg");

	return 0;
}

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I think that's not as easy as that code