#ifdef WIN32

#include <windows.h>

#endif


#include <stdio.h>
#include <stdlib.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

int winWidth ;
int winHeight ;

int imgWidth ;
int imgHeight ;

int KPOP = 256 ;


byte *sourceImage = NULL ;

// functions to load PPM files
int getHeaderPPM(FILE *fp, int *x, int *y) ;
int loadPPM(FILE *fp, byte *im, int x, int y) ;
byte * loadPPM(char *fname, byte *im) ;




void init()
{
	glMatrixMode(GL_PROJECTION) ;
	glLoadIdentity() ;
	gluOrtho2D(0,winWidth,0,winHeight) ;
}

void display () {
	glClearColor(.1f,.1f,.1f, 1.f);   /* set the background colour */
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();


	glRasterPos3d(0,0,0.0);
	glDrawPixels(imgWidth,imgHeight,
		GL_RGB,GL_UNSIGNED_BYTE,sourceImage);
	
	
	glRasterPos3d(imgWidth,0,0.0) ;
	// Here you draw the new image. You will have to creat an RGB image
	// and use glDrawPixels(......) as above

	glFlush();
	glutSwapBuffers();
}



void handleKey(byte key, int x, int y) {
  switch (key) {
  case 'q': 
	  exit(0);
	  break ;
  }
}




main(int argc, char *argv[]) {


  // read image
  char fname[100] ;
  if( argc == 1 )
	strcpy(fname,"test.ppm") ;
  else 
	strcpy(fname,argv[1]) ;

  // load the file
  sourceImage = loadPPM(fname, sourceImage) ;
  if( sourceImage == NULL ) exit(-1) ;
  
  // now we know the dimensions
  winWidth = 2*imgWidth ;
  winHeight = imgHeight ;


  glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
  glutInitWindowPosition (0, 0);
  glutInitWindowSize(winWidth,winHeight);

  int mainWindowID = glutCreateWindow(argv[0]);

  glutKeyboardFunc(handleKey);
  glutDisplayFunc(display);

  printf("Press 'q' to quit\n");

  init() ;

  glutMainLoop();
  return 0;         // never reached

}


byte *loadPPM(char *fname, byte *im)
{
    FILE *fp ;
  
    if(im != NULL)
    {
	free(im) ;
	im = NULL ;
    }


    fp = fopen(fname,"r") ;
    if(	fp == NULL )
    {
	fprintf(stderr,"loadPPM: Cannot open file %s.", fname) ;
	return NULL;
    }

    // read the header
    if( getHeaderPPM(fp, &imgWidth, &imgHeight) == -1 )
    {
	fprintf(stderr,"loadPPM: Error reading file.") ;
	return NULL ;
    }
    
    if( imgWidth * imgHeight > 10000000 )
    {
	fprintf(stderr,"loadPPM: File too big.") ;
	return NULL ;
    }

        
    // alocate image
    if((im = (GLubyte *) malloc(sizeof(GLubyte *)*imgWidth*imgHeight*3)) == NULL)
    {
	fprintf(stderr,"Not enough memory!\n") ;
	return NULL ;
    }
    
    // read the image
    if(	loadPPM(fp, im, imgWidth, imgHeight) == -1 )
    {
	fprintf(stderr,"ERROR: image was not loaded.\n") ;
	return NULL ;
    }

    /**
    for(  i = 0	; i < x	; i++ )
	for(  j	= 0 ; j	< y; j++)
	    printf("%d %d %d\n", im[i][j][0],im[i][j][1],
		   im[i][j][2])	;
		   **/
 
    
    fclose(fp) ;
    return im ;
}


int getHeaderPPM(FILE *fp, int *x, int *y)
{ 
    char s[256] ;
    s[0] = '\0' ;
    fgets(s,100,fp) ;
    if( strncmp(s, "P6", 2) != 0 )
    {
	fprintf(stderr,"Wrong format must be P6.") ;
	return -1;
    }
    fgets(s,100,fp);
    if( sscanf(s, "%d %d", x, y) != 2 )
    {
	fprintf(stderr,"Wrong format expected <x> <y>.") ;
	return -1;
    }
	fgets(s,100,fp);
	int maxCol ;
    if( sscanf(s, "%d", &maxCol) != 1 )
    {
	fprintf(stderr,"Wrong format expected <maxCol>.") ;
	return -1;
    }
    return 1 ;
}    

// Header must be read already
int loadPPM(FILE *fp, byte *im, int x, int y)
{
    int	i,j;
 
   	int count = 0 ;
    for( i = 0 ; i < x ; i++ )
	for( j = 0 ; j < y; j++)
	{
	   if(feof(fp))	
	   {
	       fprintf(stderr,"loadPPM: unexpected end of file.") ;
	       return -1 ;
	   }
	   else
	   {
			fread((void *) &im[count] , sizeof(GLubyte), 3, fp) ;
			count += 3 ;
	   }
	}

    fprintf(stderr,"File read properly.") ;
    return 1 ;
}