opengl入门例题（读取bmp图片，并显示）

#include
#define FileName "bliss.bmp"
static GLint imagewidth;
static GLint imageheight;
static GLint pixellength;
static GLubyte* pixeldata;

#include
#include
void display(void)
{
 //glClear(GL_COLOR_BUFFER_BIT);

 //绘制像素
 glDrawPixels(imagewidth,imageheight,GL_BGR_EXT,GL_UNSIGNED_BYTE,pixeldata);

 //---------------------------------
 glFlush();
 glutSwapBuffers();
}
int main(int argc,char* argv[])
{
 //打开文件
 FILE* pfile=fopen("bliss.bmp","rb");
 if(pfile == 0) exit(0);

 //读取图像大小
 fseek(pfile,0x0012,SEEK_SET);
 fread(&imagewidth,sizeof(imagewidth),1,pfile);
 fread(&imageheight,sizeof(imageheight),1,pfile);

 //计算像素数据长度
 pixellength=imagewidth*3;
 while(pixellength%4 != 0)pixellength++;
 pixellength *= imageheight;

 //读取像素数据
 pixeldata = (GLubyte*)malloc(pixellength);
 if(pixeldata == 0) exit(0);

 fseek(pfile,54,SEEK_SET);
 fread(pixeldata,pixellength,1,pfile);
 
 //关闭文件
 fclose(pfile);

 //初始化glut运行
 glutInit(&argc,argv);
 glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA);
 glutInitWindowPosition(100,100);
 glutInitWindowSize(imagewidth,imageheight);
 glutCreateWindow(FileName);
 glutDisplayFunc(&display);
 glutMainLoop();
//-------------------------------------
 free(pixeldata);
 return 0;
}