// Demonstrate correctness of OpenGL blit

#include <stdio.h>			// Header File For Standard Input / Output
#include <stdarg.h>			// Header File For Variable Argument Routines
#include <string.h>			// Header File For String Management
#include <stdlib.h>
#include <OpenGL/gl.h>				// Header File For The OpenGL32 Library
//#include <glu.h>			// Header File For The GLu32 Library
#include <GLUT/glut.h>			// Header File For The GLUT Library
#include <math.h>

// Constants -----------------------------------------------------------------

#define kWindowWidth	600
#define kWindowHeight	600

int ww = kWindowWidth;
int hh = kWindowHeight;

GLuint fbIds[1] = {0};
GLuint rbIds[1] = {0};


// Function Prototypes -------------------------------------------------------

GLvoid InitGL(GLvoid);
GLvoid DrawGLScene(GLvoid);
GLvoid ReSizeGLScene(int Width, int Height);

void glError(int ll) {
  int errnum = glGetError();
  if (errnum != 0) {
    printf("OpenGL Error: %d %x\n", ll, errnum);

    switch (errnum) {
    case GL_INVALID_ENUM:
      printf("Invalid Enum\n");
      break;
    case GL_INVALID_VALUE:
      printf("Invalid Value\n");
      break;
    default:
      break;
    }
  }
}

// Main ----------------------------------------------------------------------

int main(int argc, char** argv)
{
	
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize (kWindowWidth, kWindowHeight); 
    glutInitWindowPosition (100, 100);
    glutCreateWindow (argv[0]);
	
    InitGL();
 
    glutDisplayFunc(DrawGLScene); 
    glutReshapeFunc(ReSizeGLScene); 

    glutMainLoop();
    
    return 0;
}

// Init ----------------------------------------------------------------------

GLvoid InitGL(GLvoid)
{
  printf("InitGL\n");
}

// DrawGLScene ---------------------------------------------------------------

GLvoid DrawGLScene(GLvoid)
{    
  printf("DrawGLScene\n");

  glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
  {
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glClearColor(0, 0, 1, 0.5);
    glClear(GL_COLOR_BUFFER_BIT);
  }

  glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, fbIds[0]);
  glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, 0);

  glBlitFramebufferEXT(0, 0, ww, hh,
		       0, 0, ww, hh,
		       GL_COLOR_BUFFER_BIT,
		       GL_NEAREST);

  glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

  glFlush();
  glError(999);
}

// ReSizeGLScene ------------------------------------------------------------

GLvoid ReSizeGLScene(int Width, int Height)
{
  printf("Resize: %d %d\n", Width, Height);

  ww = Width;
  hh = Height;

  if (fbIds[0] == 0) {
    // The framebuffer has never been allocated
    glGenFramebuffersEXT(1, fbIds);
  }

  if (rbIds[0] != 0) {
    // Remove the renderbuffer if window has changed size
    glDeleteRenderbuffersEXT(1, rbIds);
  }

  glFlush();
  glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbIds[0]);

  glGenRenderbuffersEXT(1, rbIds);
  glFlush();
  glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, rbIds[0]);
  glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGB8, ww, hh);
  glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, rbIds[0]);

  glFlush();
  int status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
  if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
    printf("Buffer not completed: %d\n", status);
  }

  glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
  glClear(GL_COLOR_BUFFER_BIT);

  glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
  glError(1999);
}