Hi I need 2 different routines
I need them seperate because I need to study what it takes to put what I draw from screen to disk and also vis Versa. I f anyone has any idea of how to do this with least amount of code and not break the Open_gl flow to much. Please let me know how I can just that. Please no spagette code Im just beginning to code in open gl
Whats an I file to load??? ***
GL_glue Out
I downloaded this code from some site what do I have to set up to call this from main
and should I plug this into my drawing code just above main?
I figure I just input a filename into string variable then call LoadDIBitmap to load and SaveDIBitmap to save file 
/*
- Windows BMP file functions for OpenGL.
- Written by Michael Sweet.
*/
#include “bitmap.h”
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#ifdef WIN32
/*
- ‘LoadDIBitmap()’ - Load a DIB/BMP file from disk.
- Returns a pointer to the bitmap if successful, NULL otherwise…
*/
GLubyte * /* O - Bitmap data */
LoadDIBitmap(const char filename, / I - File to load */ <------ I file to load ***
BITMAPINFO *info) / O - Bitmap information */
{
FILE fp; / Open file pointer */
GLubyte bits; / Bitmap pixel bits /
int bitsize; / Size of bitmap /
int infosize; / Size of header information /
BITMAPFILEHEADER header; / File header */
/* Try opening the file; use "rb" mode to read this *binary* file. */
if ((fp = fopen(filename, "rb")) == NULL)
return (NULL);
/* Read the file header and any following bitmap information... */
if (fread(&header, sizeof(BITMAPFILEHEADER), 1, fp) < 1)
{
/* Couldn't read the file header - return NULL... */
fclose(fp);
return (NULL);
}
if (header.bfType != 'MB') /* Check for BM reversed... */
{
/* Not a bitmap file - return NULL... */
fclose(fp);
return (NULL);
}
infosize = header.bfOffBits - sizeof(BITMAPFILEHEADER);
if ((*info = (BITMAPINFO *)malloc(infosize)) == NULL)
{
/* Couldn't allocate memory for bitmap info - return NULL... */
fclose(fp);
return (NULL);
}
if (fread(*info, 1, infosize, fp) < infosize)
{
/* Couldn't read the bitmap header - return NULL... */
free(*info);
fclose(fp);
return (NULL);
}
/* Now that we have all the header info read in, allocate memory for *
* the bitmap and read *it* in... */
if ((bitsize = (*info)->bmiHeader.biSizeImage) == 0)
bitsize = ((*info)->bmiHeader.biWidth *
(*info)->bmiHeader.biBitCount + 7) / 8 *
abs((*info)->bmiHeader.biHeight);
if ((bits = malloc(bitsize)) == NULL)
{
/* Couldn't allocate memory - return NULL! */
free(*info);
fclose(fp);
return (NULL);
}
if (fread(bits, 1, bitsize, fp) < bitsize)
{
/* Couldn't read bitmap - free memory and return NULL! */
free(*info);
free(bits);
fclose(fp);
return (NULL);
}
/* OK, everything went fine - return the allocated bitmap... */
fclose(fp);
return (bits);
}
/*
- ‘SaveDIBitmap()’ - Save a DIB/BMP file to disk.
- Returns 0 on success or -1 on failure…
*/
int /* O - 0 = success, -1 = failure */
SaveDIBitmap(const char filename, / I - File to load */
BITMAPINFO info, / I - Bitmap information */
GLubyte bits) / I - Bitmap data */
{
FILE fp; / Open file pointer /
int size, / Size of file /
infosize, / Size of bitmap info /
bitsize; / Size of bitmap pixels /
BITMAPFILEHEADER header; / File header */
/* Try opening the file; use "wb" mode to write this *binary* file. */
if ((fp = fopen(filename, "wb")) == NULL)
return (-1);
/* Figure out the bitmap size */
if (info->bmiHeader.biSizeImage == 0)
bitsize = (info->bmiHeader.biWidth *
info->bmiHeader.biBitCount + 7) / 8 *
abs(info->bmiHeader.biHeight);
else
bitsize = info->bmiHeader.biSizeImage;
/* Figure out the header size */
infosize = sizeof(BITMAPINFOHEADER);
switch (info->bmiHeader.biCompression)
{
case BI_BITFIELDS :
infosize += 12; /* Add 3 RGB doubleword masks */
if (info->bmiHeader.biClrUsed == 0)
break;
case BI_RGB :
if (info->bmiHeader.biBitCount > 8 &&
info->bmiHeader.biClrUsed == 0)
break;
case BI_RLE8 :
case BI_RLE4 :
if (info->bmiHeader.biClrUsed == 0)
infosize += (1 << info->bmiHeader.biBitCount) * 4;
else
infosize += info->bmiHeader.biClrUsed * 4;
break;
}
size = sizeof(BITMAPFILEHEADER) + infosize + bitsize;
/* Write the file header, bitmap information, and bitmap pixel data... */
header.bfType = 'MB'; /* Non-portable... sigh */
header.bfSize = size;
header.bfReserved1 = 0;
header.bfReserved2 = 0;
header.bfOffBits = sizeof(BITMAPFILEHEADER) + infosize;
if (fwrite(&header, 1, sizeof(BITMAPFILEHEADER), fp) < sizeof(BITMAPFILEHEADER))
{
/* Couldn't write the file header - return... */
fclose(fp);
return (-1);
}
if (fwrite(info, 1, infosize, fp) < infosize)
{
/* Couldn't write the bitmap header - return... */
fclose(fp);
return (-1);
}
if (fwrite(bits, 1, bitsize, fp) < bitsize)
{
/* Couldn't write the bitmap - return... */
fclose(fp);
return (-1);
}
/* OK, everything went fine - return... */
fclose(fp);
return (0);
}
#else /* !WIN32 /
/
- Functions for reading and writing 16- and 32-bit little-endian integers.
*/
static unsigned short read_word(FILE *fp);
static unsigned int read_dword(FILE *fp);
static int read_long(FILE *fp);
static int write_word(FILE *fp, unsigned short w);
static int write_dword(FILE *fp, unsigned int dw);
static int write_long(FILE *fp, int l);
/*
- ‘LoadDIBitmap()’ - Load a DIB/BMP file from disk.
- Returns a pointer to the bitmap if successful, NULL otherwise…
*/
GLubyte * /* O - Bitmap data */
LoadDIBitmap(const char filename, / I - File to load */
BITMAPINFO *info) / O - Bitmap information */
{
FILE fp; / Open file pointer */
GLubyte bits; / Bitmap pixel bits */
GLubyte ptr; / Pointer into bitmap /
GLubyte temp; / Temporary variable to swap red and blue /
int x, y; / X and Y position in image /
int length; / Line length /
int bitsize; / Size of bitmap /
int infosize; / Size of header information /
BITMAPFILEHEADER header; / File header */
/* Try opening the file; use "rb" mode to read this *binary* file. */
if ((fp = fopen(filename, "rb")) == NULL)
return (NULL);
/* Read the file header and any following bitmap information... */
header.bfType = read_word(fp);
header.bfSize = read_dword(fp);
header.bfReserved1 = read_word(fp);
header.bfReserved2 = read_word(fp);
header.bfOffBits = read_dword(fp);
if (header.bfType != BF_TYPE) /* Check for BM reversed... */
{
/* Not a bitmap file - return NULL... */
fclose(fp);
return (NULL);
}
infosize = header.bfOffBits - 18;
if ((*info = (BITMAPINFO *)malloc(sizeof(BITMAPINFO))) == NULL)
{
/* Couldn't allocate memory for bitmap info - return NULL... */
fclose(fp);
return (NULL);
}
(*info)->bmiHeader.biSize = read_dword(fp);
(*info)->bmiHeader.biWidth = read_long(fp);
(*info)->bmiHeader.biHeight = read_long(fp);
(*info)->bmiHeader.biPlanes = read_word(fp);
(*info)->bmiHeader.biBitCount = read_word(fp);
(*info)->bmiHeader.biCompression = read_dword(fp);
(*info)->bmiHeader.biSizeImage = read_dword(fp);
(*info)->bmiHeader.biXPelsPerMeter = read_long(fp);
(*info)->bmiHeader.biYPelsPerMeter = read_long(fp);
(*info)->bmiHeader.biClrUsed = read_dword(fp);
(*info)->bmiHeader.biClrImportant = read_dword(fp);
if (infosize > 40)
if (fread((*info)->bmiColors, infosize - 40, 1, fp) < 1)
{
/* Couldn't read the bitmap header - return NULL... */
free(*info);
fclose(fp);
return (NULL);
}
/* Now that we have all the header info read in, allocate memory for *
* the bitmap and read *it* in... */
if ((bitsize = (*info)->bmiHeader.biSizeImage) == 0)
bitsize = ((*info)->bmiHeader.biWidth *
(*info)->bmiHeader.biBitCount + 7) / 8 *
abs((*info)->bmiHeader.biHeight);
if ((bits = malloc(bitsize)) == NULL)
{
/* Couldn't allocate memory - return NULL! */
free(*info);
fclose(fp);
return (NULL);
}
if (fread(bits, 1, bitsize, fp) < bitsize)
{
/* Couldn't read bitmap - free memory and return NULL! */
free(*info);
free(bits);
fclose(fp);
return (NULL);
}
/* Swap red and blue */
length = ((*info)->bmiHeader.biWidth * 3 + 3) & ~3;
for (y = 0; y < (*info)->bmiHeader.biHeight; y ++)
for (ptr = bits + y * length, x = (*info)->bmiHeader.biWidth;
x > 0;
x --, ptr += 3)
{
temp = ptr[0];
ptr[0] = ptr[2];
ptr[2] = temp;
}
/* OK, everything went fine - return the allocated bitmap... */
fclose(fp);
return (bits);
}
/*
- ‘SaveDIBitmap()’ - Save a DIB/BMP file to disk.
- Returns 0 on success or -1 on failure…
*/
int /* O - 0 = success, -1 = failure */
SaveDIBitmap(const char filename, / I - File to load */
BITMAPINFO info, / I - Bitmap information */
GLubyte bits) / I - Bitmap data */
{
FILE fp; / Open file pointer /
int size, / Size of file /
infosize, / Size of bitmap info /
bitsize; / Size of bitmap pixels */
/* Try opening the file; use "wb" mode to write this *binary* file. */
if ((fp = fopen(filename, "wb")) == NULL)
return (-1);
/* Figure out the bitmap size */
if (info->bmiHeader.biSizeImage == 0)
bitsize = (info->bmiHeader.biWidth *
info->bmiHeader.biBitCount + 7) / 8 *
abs(info->bmiHeader.biHeight);
else
bitsize = info->bmiHeader.biSizeImage;
/* Figure out the header size */
infosize = sizeof(BITMAPINFOHEADER);
switch (info->bmiHeader.biCompression)
{
case BI_BITFIELDS :
infosize += 12; /* Add 3 RGB doubleword masks */
if (info->bmiHeader.biClrUsed == 0)
break;
case BI_RGB :
if (info->bmiHeader.biBitCount > 8 &&
info->bmiHeader.biClrUsed == 0)
break;
case BI_RLE8 :
case BI_RLE4 :
if (info->bmiHeader.biClrUsed == 0)
infosize += (1 << info->bmiHeader.biBitCount) * 4;
else
infosize += info->bmiHeader.biClrUsed * 4;
break;
}
size = sizeof(BITMAPFILEHEADER) + infosize + bitsize;
/* Write the file header, bitmap information, and bitmap pixel data... */
write_word(fp, BF_TYPE); /* bfType */
write_dword(fp, size); /* bfSize */
write_word(fp, 0); /* bfReserved1 */
write_word(fp, 0); /* bfReserved2 */
write_dword(fp, 18 + infosize); /* bfOffBits */
write_dword(fp, info->bmiHeader.biSize);
write_long(fp, info->bmiHeader.biWidth);
write_long(fp, info->bmiHeader.biHeight);
write_word(fp, info->bmiHeader.biPlanes);
write_word(fp, info->bmiHeader.biBitCount);
write_dword(fp, info->bmiHeader.biCompression);
write_dword(fp, info->bmiHeader.biSizeImage);
write_long(fp, info->bmiHeader.biXPelsPerMeter);
write_long(fp, info->bmiHeader.biYPelsPerMeter);
write_dword(fp, info->bmiHeader.biClrUsed);
write_dword(fp, info->bmiHeader.biClrImportant);
if (infosize > 40)
if (fwrite(info->bmiColors, infosize - 40, 1, fp) < 1)
{
/* Couldn't write the bitmap header - return... */
fclose(fp);
return (-1);
}
if (fwrite(bits, 1, bitsize, fp) < bitsize)
{
/* Couldn't write the bitmap - return... */
fclose(fp);
return (-1);
}
/* OK, everything went fine - return... */
fclose(fp);
return (0);
}
/*
- ‘read_word()’ - Read a 16-bit unsigned integer.
*/
static unsigned short /* O - 16-bit unsigned integer */
read_word(FILE fp) / I - File to read from /
{
unsigned char b0, b1; / Bytes from file */
b0 = getc(fp);
b1 = getc(fp);
return ((b1 << 8) | b0);
}
/*
- ‘read_dword()’ - Read a 32-bit unsigned integer.
*/
static unsigned int /* O - 32-bit unsigned integer */
read_dword(FILE fp) / I - File to read from /
{
unsigned char b0, b1, b2, b3; / Bytes from file */
b0 = getc(fp);
b1 = getc(fp);
b2 = getc(fp);
b3 = getc(fp);
return ((((((b3 << 8) | b2) << 8) | b1) << 8) | b0);
}
/*
- ‘read_long()’ - Read a 32-bit signed integer.
*/
static int /* O - 32-bit signed integer */
read_long(FILE fp) / I - File to read from /
{
unsigned char b0, b1, b2, b3; / Bytes from file */
b0 = getc(fp);
b1 = getc(fp);
b2 = getc(fp);
b3 = getc(fp);
return ((int)(((((b3 << 8) | b2) << 8) | b1) << 8) | b0);
}
/*
- ‘write_word()’ - Write a 16-bit unsigned integer.
*/
static int /* O - 0 on success, -1 on error */
write_word(FILE fp, / I - File to write to /
unsigned short w) / I - Integer to write */
{
putc(w, fp);
return (putc(w >> 8, fp));
}
/*
- ‘write_dword()’ - Write a 32-bit unsigned integer.
*/
static int /* O - 0 on success, -1 on error */
write_dword(FILE fp, / I - File to write to /
unsigned int dw) / I - Integer to write */
{
putc(dw, fp);
putc(dw >> 8, fp);
putc(dw >> 16, fp);
return (putc(dw >> 24, fp));
}
/*
- ‘write_long()’ - Write a 32-bit signed integer.
*/
static int /* O - 0 on success, -1 on error */
write_long(FILE fp, / I - File to write to /
int l) / I - Integer to write /
{
putc(l, fp);
putc(l >> 8, fp);
putc(l >> 16, fp);
return (putc(l >> 24, fp));
}
#endif / WIN32 */
is this good code??? or no
seems to be to many save routines confusing Please help
with super spagette code 
[This message has been edited by Gl_glue (edited 03-12-2001).]
[This message has been edited by Gl_glue (edited 03-12-2001).]