image.cpp

关于OpenGL的实例教程源代码

/*******************************************************************************/
/*********************************21/09/200*************************************/
/**********************Programmer: Dimitrios Christopoulos**********************/
/**********************for the oglchallenge contest*****************************/
/**********************COLLISION CRAZY******************************************/
/*******************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include "image.h"
/*
 * getint and getshort arehelp functions to load the bitmap byte by byte on 
 * SPARC platform.
 * I've got them from xv bitmap load routinebecause the original bmp loader didn't work
 * I've tried to change as less code as possible.
 */

static unsigned int getint(FILE *fp)
{
  int c, c1, c2, c3;

  /* get 4 bytes*/
  c = getc(fp);  
  c1 = getc(fp);  
  c2 = getc(fp);  
  c3 = getc(fp);
  
  return ((unsigned int) c) +   
    (((unsigned int) c1) << 8) + 
    (((unsigned int) c2) << 16) +
    (((unsigned int) c3) << 24);
}

static unsigned int getshort(FILE *fp)
{
  int c, c1;
  
  /*get 2 bytes*/
  c = getc(fp);  
  c1 = getc(fp);
 
  return ((unsigned int) c) + (((unsigned int) c1) << 8);
 
}
    

/* quick and dirty bitmap loader...for 24 bit bitmaps with 1 plane only.  */
/* See http://www.dcs.ed.ac.uk/~mxr/gfx/2d/BMP.txt for more info.*/

int ImageLoad(char *filename, Image *image) {
    FILE *file;
    unsigned long size;                 /* size of the image in bytes.*/
    unsigned long i;                    /* standard counter.*/
    unsigned short int planes;          /* number of planes in image (must be 1) */
    unsigned short int bpp;             /* number of bits per pixel (must be 24)*/
    char temp;                          /* temporary color storage for bgr-rgb conversion.*/

    /* make sure the file is there.*/
    if ((file = fopen(filename, "rb"))==NULL) {
      printf("File Not Found : %s\n",filename);
      return 0;
    }
    
    /* seek through the bmp header, up to the width/height:*/
    fseek(file, 18, SEEK_CUR);

    /* No 100% errorchecking anymore!!!*/

    /* read the width*/
    image->sizeX = getint (file);
    printf("Width of %s: %lu\n", filename, image->sizeX);
    
    /* read the height */
    image->sizeY = getint (file);
    printf("Height of %s: %lu\n", filename, image->sizeY);
    
    /* calculate the size (assuming 24 bits or 3 bytes per pixel).*/
    size = image->sizeX * image->sizeY * 3;

    /* read the planes*/
    planes = getshort(file);
    if (planes != 1) {
	printf("Planes from %s is not 1: %u\n", filename, planes);
	return 0;
    }

    /* read the bpp*/
    bpp = getshort(file);
    if (bpp != 24) {
	printf("Bpp from %s is not 24: %u\n", filename, bpp);
	return 0;
    }
	
    /* seek past the rest of the bitmap header.*/
    fseek(file, 24, SEEK_CUR);

    /* read the data. */
    image->data = (char *) malloc(size);
    if (image->data == NULL) {
	printf("Error allocating memory for color-corrected image data");
	return 0;	
    }

    if ((i = fread(image->data, size, 1, file)) != 1) {
	printf("Error reading image data from %s.\n", filename);
	return 0;
    }

    for (i=0;i<size;i+=3) { /* reverse all of the colors. (bgr -> rgb)*/
	temp = image->data[i];
	image->data[i] = image->data[i+2];
	image->data[i+2] = temp;
    }
    
    /* we're done.*/
    return 1;
}