opengl 加載bmp做紋理

在學習OPENGL過程中，紅皮書上的例子紋理都是現生成的方格圖檔，太難看，今天在網上找到一個方法，可以很友善的加載你想要的圖檔，感謝此方法的編寫者（忘記了出處，請原諒!）。

//注意:width height要與實際圖檔相同；另外filename必須指向BMP圖檔，其它編碼格式請先轉碼

GLuint LoadTexture( const char * filename, int width, int height )

    {

GLuint texture;

unsigned char * data;

FILE * file;

//The following code will read in our PNG file

file = fopen( filename, "rb" );

if ( file == NULL ) return 0;

data = (unsigned char *)malloc( width * height * 3 );

fread( data, width * height * 3, 1, file );

fclose( file );

glGenTextures( 1, &texture ); //generate the texture with 

glBindTexture( GL_TEXTURE_2D, texture ); //bind the texture

glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, 

GL_MODULATE ); //set texture environment parameters

//even better quality, but this will do for now.

glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,

GL_LINEAR );

glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,

GL_LINEAR );

//Here we are setting the parameter to repeat the texture 

//to the edge of our shape. 

glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, 

GL_REPEAT );

glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, 

GL_REPEAT );

//Generate the texture

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0,

GL_RGB, GL_UNSIGNED_BYTE, data);

free( data ); //free the texture

return texture; //return whether it was successfull

}