the opengl code problem?

[C++ Programming]

#include
#include
#include
#include
#include
#include
static GLfloat f1,f2,f3;

static void initA(void)
{
GLfloat fogColor[4]={0.0,0.25,0.25,1.0};
f1=1.0f;
f2=5.0f;
f3=10.0f;
glEnable(GL_FOG);
glFogi(GL_FOG_MODE,GL_EXP);
glFogfv(GL_FOG_COLOR,fogColor);
glFogf(GL_FOG_DENSITY,0.25);
glHint(GL_FOG_HINT,GL_DONT_CARE);
glFogi(GL_FOG_COORDINATE_SOURCE_EXT,GL_FOG_COORDINATE_EXT);
glClearColor(0.0,0.25,0.25,1.0);
}

void displayA(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,0.75,0.0);
glBegin(GL_TRIANGLES);
glFogCoordfEXT(f1);
glVertex3f(0.2f,0.2f,0.0f);
glFogCoordfEXT(f2);
glVertex3f(-0.2f,0.0f,-0.5f);
glFogCoordfEXT(f3);
glVertex3f(0.0f,0.2f,-1.0f);
glEnd();
//glFlush();
glutSwapBuffers();
}
void reshapeA(int w,int h)
{
glViewport(0,0,(GLint)w,(GLint)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0,1.0,0.25,25.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0,0.0,-5.0);
}
void keyboardA(unsigned char key,int x,int y)
{
switch(key)
{
case 'c':
glFogi(GL_FOG_COORDINATE_SOURCE_EXT,GL_FRAGMENT_DEPTH);
glutPostRedisplay();
break;
case 'C':
glFogi(GL_FOG_COORDINATE_SOURCE_EXT,GL_FOG_COORDINATE);
glutPostRedisplay();
break;
case '1':
f1=f1+0.25;
glutPostRedisplay();
break;
case '2':
f2=f2+0.25;
glutPostRedisplay();
break;
case '3':
f3=f3+0.25;
glutPostRedisplay();
break;
case '8':
if(f1>0.25)
{
f1=f1-0.25;
glutPostRedisplay();
}
break;
case '9':
if(f2>0.25)
{
f2=f2-0.25;
glutPostRedisplay();
}
break;
case '0':
if(f3>0.25)
{
f3=f3-0.25;
glutPostRedisplay();
}
break;
case 'b':
glMatrixMode(GL_MODELVIEW);
glTranslatef(0.0,0.0,-0.25);
glutPostRedisplay();
break;
case 'f':
glMatrixMode(GL_MODELVIEW);
glTranslatef(0.0,0.0,0.25);
glutPostRedisplay();
break;
case 27:
exit(0);
break;
default:
break;
}
}
int main(int argc,char** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(400,400);
glutCreateWindow("????");
initA();
glutReshapeFunc(reshapeA);
glutKeyboardFunc(keyboardA);
glutDisplayFunc(displayA);
glutMainLoop();
return 0;
}