VC运用OPENGL加载BMP纹理图的实现方法汇总

来源：本站原创|时间：2020-01-10|栏目：C语言|点击：次

OpenGL是专业的图形程序接口，功能非常强大，调用方便的底层图形库。本文汇总了运用OPENGL加载BMP纹理图的几个实现方法。

方法一：

首先获取位图句柄：

HBITMAP hBmp = (HBITMAP) ::LoadImage (AfxGetResourceHandle(),MAKEINTRESOURCE(IDB_BITMAP1), IMAGE_BITMAP, 0, 0,LR_CREATEDIBSECTION);

然后根据位图句柄得到位图信息：

BITMAP BM;
::GetObject (hBmp, sizeof (BM), &BM);

最后根据位图信息中的RGB值建立纹理：

gluBuild2DMipmaps( GL_TEXTURE_2D, 3, BM.bmWidth, BM.bmHeight,GL_BGR_EXT, GL_UNSIGNED_BYTE,BM.bmBits);

方法二：

首先用OpenGL辅助库获得位图信息：

AUX_RGBImageRec* TextureImage[1];
TextureImage[0]=auxDIBImageLoad("1.bmp");

然后建立纹理

gluBuild2DMipmaps(GL_TEXTURE_2D, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);

方法三：

从底层做，需要了解bmp文件的结构，首先读取bmp文件结构，包括文件头、信息头和数据，数据用于后面定义纹理

long ImageWidth=256;
long ImageHeight=256; 
GLubyte Image[256][256][3];
void ReadHeader(FILE *fp , BITMAPFH * p_bitmapheader , BITMAPIH *p_bitmapinfo) 
{
 fseek(fp, 0, SEEK_SET) ;
 fread( &p_bitmapheader->bfType,sizeof(unsigned short), 1, fp );
 fseek(fp, 2, SEEK_SET) ;
 fread( &p_bitmapheader->bfSize,sizeof(unsigned long), 1, fp );
 fseek(fp, 6, SEEK_SET) ;
 fread( &p_bitmapheader->bfReserved1,sizeof(unsigned short), 1, fp );
 fseek(fp, 8, SEEK_SET) ;
 fread( &p_bitmapheader->bfReserved2,sizeof(unsigned short), 1, fp );
 fseek(fp, 10, SEEK_SET) ;
 fread( &p_bitmapheader->bfOffBits,sizeof(unsigned long), 1, fp );
 fseek(fp, 14, SEEK_SET) ;
 fread( &p_bitmapinfo->biSize, sizeof(unsigned long), 1, fp );
 fseek(fp, 18, SEEK_SET) ;
 fread( &p_bitmapinfo->biWidth, sizeof(unsigned long), 1, fp );
 fseek(fp, 22, SEEK_SET) ;
 fread( &p_bitmapinfo->biHeight, sizeof(unsigned long), 1, fp );
 fseek(fp, 26, SEEK_SET) ;
 fread( &p_bitmapinfo->biPlanes, sizeof(unsigned short), 1, fp );
 fseek(fp, 28, SEEK_SET) ;
 fread( &p_bitmapinfo->biBitCount, sizeof(unsigned short), 1, fp );
 fseek(fp, 30, SEEK_SET) ;
 fread( &p_bitmapinfo->biCompression, sizeof(unsigned long), 1, fp );
 fseek(fp, 34, SEEK_SET) ;
 fread( &p_bitmapinfo->biSizeImage, sizeof(unsigned long), 1, fp );
 fseek(fp, 38, SEEK_SET) ;
 fread( &p_bitmapinfo->biXPelsPerMeter, sizeof(unsigned long), 1, fp );
 fseek(fp, 42, SEEK_SET) ;
 fread( &p_bitmapinfo->biYPelsPerMeter, sizeof(unsigned long), 1, fp );
 fseek(fp, 46, SEEK_SET) ;
 fread( &p_bitmapinfo->biClrUsed, sizeof(unsigned long), 1, fp );
 fseek(fp, 50, SEEK_SET) ;
 fread( &p_bitmapinfo->biClrImportant, sizeof(unsigned long), 1, fp );
}
void ReadBitmapFile()
{
 BITMAPFH bitmapheader ;
 BITMAPIH bitmapinfo ;
 FILE *fp;
 fp = fopen("6.bmp" , "r") ;
 if(!fp)
 {
  puts("Read file failed.") ;
  return;
 }
 ReadHeader(fp, &bitmapheader , &bitmapinfo) ;
 if(bitmapinfo.biBitCount != 24)
 {
  puts("UNSUPPORT") ;
  return;
 }
 ImageWidth = bitmapinfo.biWidth;
 ImageHeight = bitmapinfo.biHeight;
 int i=bitmapheader.bfOffBits;
 while(i<bitmapheader.bfSize)
 {
  for(int j=0;j<ImageWidth;j++)
  for(int k=0;k<ImageHeight;k++)
  {
   fseek(fp, i, SEEK_SET) ;
   fread(Image[j][k]+2, 1, 1, fp) ;
   fseek(fp, i+1, SEEK_SET) ;
   fread(Image[j][k]+1, 1, 1, fp) ;
   fseek(fp, i+2, SEEK_SET) ;
   fread(Image[j][k], 1, 1, fp) ;
   i=i+3;
  } 
 } 
 fclose(fp) ;
}
glTexImage2D(GL_TEXTURE_2D,0,3,ImageWidth,ImageHeight,0,GL_RGB,GL_UNSIGNED_BYTE,&Image[0][0][0]);

#include <gl\glext.h>
这是因为后面的GL_BGR_EXT是定义在这个头文件里的，因为BMP格式是按Blue,Green,Red顺序储存图像数据的，这与OpenGL中正好相反。GL_BGR_EXT就是完成两者之间的转换的。

下面就是不用AUX库来加载BMP图片作为纹理的函数：

bool LoadTexture(LPTSTR szFileName, GLuint &texid)   // Creates Texture From A Bitmap File
{
HBITMAP hBMP;       // Handle Of The Bitmap
BITMAP BMP;       // Bitmap Structure
glGenTextures(1, &texid);      // Create The Texture
hBMP=(HBITMAP)LoadImage(GetModuleHandle(NULL), szFileName, IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE );
if (!hBMP)        // Does The Bitmap Exist?
  return FALSE;       // If Not Return False
GetObject(hBMP, sizeof(BMP), &BMP);     // Get The Object
         // hBMP:    Handle To Graphics Object
         // sizeof(BMP): Size Of Buffer For Object Information
         // &BMP:    Buffer For Object Information
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);    // Pixel Storage Mode (Word Alignment / 4 Bytes)
// Typical Texture Generation Using Data From The Bitmap
glBindTexture(GL_TEXTURE_2D, texid);     // Bind To The Texture ID
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); // Linear Min Filter
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // Linear Mag Filter
glTexImage2D(GL_TEXTURE_2D, 0, 3, BMP.bmWidth, BMP.bmHeight, 0, GL_BGR_EXT, GL_UNSIGNED_BYTE, BMP.bmBits);
DeleteObject(hBMP);       // Delete The Object
return TRUE;       // Loading Was Successful
}

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