OpenGL中用bmp图片做纹理贴图的三种方法

OpenGL中用bmp图片做纹理贴图的三种方法

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

{

for(int j=0;j

for(int k=0;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]);

OpenGL中不用AUX库来加载BMP图片作为纹理［转载］(2007-02-11 21:22:15)

大家在OpenGL中一般是用aux库的auxDIBImageLoad()函数来加载BMP格式的图片来作为纹理，这个确实是比较简单易用，但aux库的性能不佳，经常会出问题，稳定性较差。所以一般最好不要用aux库，可以用glut库，但glut库没有纹理加载函数。而有些程序是直接读取BMP格式来获得图像数据，从而生成纹理的，这种方法虽然很强大，但比较复杂，需要了解BMP的格式，对初学者比较困难。而下面的一段程序是用windows的API函数LoadImage()来实现这个功能，这种实现方法很简单，可以说比auxDIBImageLoad()函数复杂不了多少。

首先，加上头文件：

#include

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

}