将背景图像添加到此代码而不是黑色？

Posted 2021-04-23

我看到这段代码，需要添加背景图片

像这样enter image description here

我怎么能这样做添加背景而不是黑色背景

请帮我

我从另一个问题得到这个代码，但我不知道如何改变背景

Create video from array of pixel values in C++

#include <iostream>
#include "CImg.h"

using namespace std;
using namespace cimg_library;

int main()
{
   const unsigned int width=1024;
   const unsigned int height=768;

   // Basic frame we will draw in
   CImg<unsigned char> image(width,height,1,3);

   unsigned char magenta[] = {255,0,255};

   // We are going to output 300 frames of 1024x768 RGB raw video
   // ... making a 10s long video at 30fps
   int radius=100;
   int cx=100;
   int cy=100;
   for(int frame=0;frame<300;frame++){
      // Start with black - it shows fewer stains ;-)
      image.fill(0);
      image.draw_circle(cx,cy,radius,magenta);

      // Move and re-colour circle
      cx+=2; cy++; if(magenta[1]!=255){magenta[1]++;}

      // Output to ffmpeg to make video, in planar GBR format
      // i.e. run program like this
      // ./main | ffmpeg -y -f rawvideo -pixel_format gbrp -video_size 1024x768 -i - -c:v h264 -pix_fmt yuv420p video.mov
      char* s=reinterpret_cast<char*>(image.data()+(width*height));   // Get start of G plane
      std::cout.write(s,width*height);                                // Output it
      s=reinterpret_cast<char*>(image.data()+2*(width*height));       // Get start of B plane
      std::cout.write(s,width*height);                                // Output it
      s=reinterpret_cast<char*>(image.data());                        // Get start of R plane
      std::cout.write(s,width*height);                                // Output it
   }
}

我用这个编译

./main | ffmpeg -y -f rawvideo -pixel_format gbrp -video_size 1024x768 -i - -c:v h264 -pix_fmt yuv420p video.mov

答案

您需要做的就是在开始时加载背景图像，然后在每次迭代时复制它以进行绘制：

#include <iostream>
#include "CImg.h"

using namespace std;
using namespace cimg_library;

int main()
{
   // Background frame we will draw 
   CImg<unsigned char> bg("background.jpg");
   bg.resize(1024,768);
   int width=bg.width();
   int height=bg.height();

   unsigned char magenta[] = {255,0,255};

   // We are going to output 300 frames of RGB raw video
   // ... making a 10s long video at 30fps
   int radius=100;
   int cx=100;
   int cy=100;
   for(int frame=0;frame<300;frame++){
      // Take copy of background image
      CImg<unsigned char> image(bg,false);

      image.draw_circle(cx,cy,radius,magenta);

      // Move and re-colour circle
      cx+=2; cy++; if(magenta[1]!=255){magenta[1]++;}

      // Output to ffmpeg to make video, in planar GBR format
      // i.e. run program like this
      // ./main | ffmpeg -y -f rawvideo -pixel_format gbrp -video_size 1024x768 -i - -c:v h264 -pix_fmt yuv420p video.mov
      char* s=reinterpret_cast<char*>(image.data()+(width*height));   // Get start of G plane
      std::cout.write(s,width*height);                                // Output it
      s=reinterpret_cast<char*>(image.data()+2*(width*height));       // Get start of B plane
      std::cout.write(s,width*height);                                // Output it
      s=reinterpret_cast<char*>(image.data());                        // Get start of R plane
      std::cout.write(s,width*height);                                // Output it
   }
}