thepowerofswift/cvrotate2d

OpenCV library for rotating a matrix without cropping

cvrotate2D

The library cvrotate2D is an OpenCV library for rotating a matrix without cropping.

How to use

void rotate2D(InputArray src, OutputArray dst, double degrees)

Example

Compile the demonstration with the following command:

g++ demo.cpp -o demo cvrotate2D.cpp -lopencv_core -lopencv_imgcodecs -lopencv_imgproc

And then execute ./demo to obtain the file rotated.png with the image rotated.

Example 2 (compiling the library)

Compile the library:

g++ -O3 -Wall -shared -fpic -o libcvrotate2D.so cvrotate2D.cpp

Compile the demonstration using the compiled library cvrotate2D:

g++ demo.cpp -o demo -lopencv_core -lopencv_highgui -lopencv_imgcodecs -lcvrotate2D -I./ -L./

Finally, execute ./demo to obtain the file frog_rotated.png with the image rotated.

Optional: C++ code to calculate the angle between two vectors

#include <opencv2/core/core.hpp>

int main()
{
   cv::Point3d A(0.0, 1.0, 0.0);
   cv::Point3d B(1.0, 0.0, 0.0);

   double cross = cv::norm(A.cross(B));
   double dot = A.dot(B);

   double angle = std::atan2(cross, dot) * 180.0 / M_PI;
   
   return 0;
}