About opengl screen shot is black

wangningyu

shot.h

/*
Class Name:

  CTGALoader.

  This class loads a tga texture into this object.
  
shot.h

*/

#ifndef CTGALOADER_H
#define CTGALOADER_H

// Remember to place all your GL/system header files that you will need to run class function

class CTGALoader
{
public:
CTGALoader(); // Constructor.
~CTGALoader(); // Destructor.

  bool LoadTGAFile(char \*filename);   // Load a .tga image file.
  void SaveTGAScreenShot(char \*filename,
                         int width,
                         int height); // Save a .tga screen shot.
  void FreeImage();                   // Delete a image.

  unsigned int ID;                    // ID used for generating the textures in OpenGl.
  int imageWidth;                     // Width of a texture.
  int imageHeight;                    // Height of a texture.

protected:
void GenerateTexture(); // Generate a texture in OpenGL.
bool LoadTGA(char *filename); // Load a tga image.
bool WriteTGA(char *file, short int width,
short int height,
unsigned char *image); // Write a tga file.

  unsigned char \*image;               // Texture image.
  bool textureExist;                  // This will be used if the image was loaded.
  int type;                           // Image format.

};

#endif

shot.cpp

/*
Class Name:

  CTGALoader.

shot.h

*/

#include"shot.h"

#include
#include <./gl/GL.H>
#include <./gl/GLU.H>
#include

#pragma comment(lib,"OPENGL32.LIB")
#pragma comment(lib,"Glu32.lib")

CTGALoader::CTGALoader()
{
// Give everything default values.
image = 0;
textureExist = false;
type = 0;
}

CTGALoader::~CTGALoader()
{
FreeImage(); // Delete all images and dynamic memory.
}

bool CTGALoader::LoadTGAFile(char *file)
{
if(textureExist)
FreeImage();

if(!LoadTGA(file))
return false;

// Make sure the image loaded.
if(image == 0)
{
return false;
}

GenerateTexture();

textureExist = true;

return true;
}

void CTGALoader::GenerateTexture()
{
// Generate the texture and text the id to the images id.
glGenTextures(1, &ID);

// Here we bind the texture and set up the filtering.
glBindTexture(GL_TEXTURE_2D, ID);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

Lost User

Far too much code here and far too few details. Try and narrow the problem down to a specific area of code and explain what is not working.

speaking as ...

Software_Developer

You have to draw some graphics first.