GLSL 多重纹理示例（源码）

#include "bitmap.h" #include <stdio.h> #include <stdlib.h> #include <errno.h> #ifdef WIN32 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 */ 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) < (unsigned)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 = (unsigned char *)malloc(bitsize)) == NULL) { /* Couldn't allocate memory - return NULL! */ free(*info); fclose(fp); return (NULL); } if (fread(bits, 1, bitsize, fp) < (unsigned)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) < (unsigned)infosize) { /* Couldn't write the bitmap header - return... */ fclose(fp); return (-1); } if (fwrite(bits, 1, bitsize, fp) < (unsigned)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