C++、opencv、图像旋转

在ubuntu系统上，用KDevelop开发环境写的代码，所以有main.cpp和CMakeLists.txt两个文件。
没有KDevelop也可以，直接mkdir build && cd build && cmake … && make
main.cpp

#include 
#include 
#include 
#include 
#include 

#define pi 3.1415926

// /usr/local/lib
// /usr/local/include/opencv2
// /usr/local/share/licenses
// /usr/local/share
// /usr/local/bin/opencv_version

using namespace std;

template<typename T, typename ... Ts> 
void print(T out)
{
    cout << out << endl;
}

double sin_(int m)
{
    return sin(m*pi/180);
}

double cos_(int m)
{
    return cos(m*pi/180);
}

//把所有度数统一到 -180 to 180
int mod(int degree)
{
    if(degree>=0) 
    {
        if(degree%360<180) return degree%360;
        else if(degree%360>180) return degree%360-360;
    }
    else if(degree<0)
    {
        if(degree>=-180) return degree;
        else
        {
            while(1)
            {
                degree+=360;
                if(degree>-180) break;
            }
            return degree;
        }
    }
}

void imshow_(cv::Mat img)
{
    cv::imshow("0",img);
}

//把src放到dst的中间，这个函数没用上，留着备用不删
void center_paste(cv::Mat &src, cv::Mat &dst)
{
    int src_w = src.cols;
    int src_h = src.rows;
    int dst_w = dst.cols;
    int dst_h = dst.rows;
    
    cv::Rect rect = cv::Rect((dst_w-src_w)/2, (dst_h-src_h)/2, src_w, src_h); //x,y,w,h
    src.copyTo(dst(rect));
}


int main(int argc, char **argv) 
{
    define the src img
    cv::Mat img;
    img = cv::imread("../3.jpg");
    int rows = img.rows;
    int cols = img.cols;
    
    cout << "src size = " << cols << ' ' << rows << endl;
    
    imshow_(img);
    cv::waitKey(0);
    
    define the dst img
    int theta = -30;  
    int rows_n,cols_n,theta_mod,theta_abs;
    theta_mod = mod(theta);  // -180 ~ 180
    cout << "real degree = " << theta_mod << endl;
    if(theta_mod<90 && theta_mod>-90)
    {
        theta_abs = abs(theta_mod);
    }
    else if(theta_mod>=90)
    {
        theta_abs = 180-theta_mod;
    }
    else if(theta_mod<=-90)
    {
        theta_abs = 180+theta_mod;
    }
    rows_n = cols*sin_(theta_abs)+rows*cos_(theta_abs);
    cols_n = cols*cos_(theta_abs)+rows*sin_(theta_abs);
    
    
    cv::Mat img_n(rows_n, cols_n, CV_8UC3, cv::Scalar(0,0,0));
    cout << "dst size = " << cols_n << ' ' << rows_n << endl;
    
    //start to roll
    //center point of the dst img
    int center_x = img_n.cols/2;
    int center_y = img_n.rows/2;
    
    for(int x=0;x<cols;x++)
    {
        for(int y=0;y<rows;y++)
        {
            //索引到欧式坐标转换，旋转
            int x_n = (x-cols/2)*cos_(theta) - (-y+rows/2)*sin_(theta); 
            int y_n = (-y+rows/2)*cos_(theta) + (x-cols/2)*sin_(theta);
            //cout << x << ' ' << y << ' ' << (x-cols/2) << ' ' << (y-rows/2) << ' ' << x_n << ' ' << y_n << endl;

            //img.at(y row,x col);
            img_n.at<cv::Vec3b>(center_y-y_n, center_x+x_n) = img.at<cv::Vec3b>(y,x);
        }
        imshow_(img_n);
        cv::waitKey(1);
    }

    //双线性插值
    for(int i=1;i<rows_n-1;i++)
    {
        for(int j=1;j<cols_n;j++)
        {
            if(img_n.at<cv::Vec3b>(i,j)[0]==0 && img_n.at<cv::Vec3b>(i,j)[1]==0 && img_n.at<cv::Vec3b>(i,j)[2]==0)
            {
                img_n.at<cv::Vec3b>(i,j)[0] = (img_n.at<cv::Vec3b>(i-1,j-1)[0]+img_n.at<cv::Vec3b>(i+1,j+1)[0])/2;
                img_n.at<cv::Vec3b>(i,j)[1] = (img_n.at<cv::Vec3b>(i-1,j-1)[1]+img_n.at<cv::Vec3b>(i+1,j+1)[1])/2;
                img_n.at<cv::Vec3b>(i,j)[2] = (img_n.at<cv::Vec3b>(i-1,j-1)[2]+img_n.at<cv::Vec3b>(i+1,j+1)[2])/2;
                
//                 img_n.at(i,j) = img_n.at(i+1,j+1);
            }
        }
    }
    
    
    //cv::imwrite("roll.jpg",img_n);
    imshow_(img_n);
    cv::waitKey(0);
    
    return 0;
    
}

CMakeLists.txt
复制的时候把注释删掉，CMake好像不能有注释

cmake_minimum_required(VERSION 3.0)
project(cv)

# using C++11
set( CMAKE_CXX_FLAGS "-std=c++11 ")

# 
//find_package会自动生成OpenCV_INCLUDE_DIRS和OpenCV_LIBS
//下面直接调用就行
find_package(OpenCV REQUIRED)

#
include_directories( ${OpenCV_INCLUDE_DIRS})

#
add_executable(cv main.cpp)

#
target_link_libraries( cv ${OpenCV_LIBS})