请大家帮忙写个OpenGL的代码（用Dev-C++）

int a=0;
void NormalKeys(unsigned char key,int x,int y)
{
if(key == 'l'|| key=='L') a=1;
else if(key == 'c' || key == 'C') a=2;
else a=0;
glutPostRedisplay();
}
void RenderScene(void)
{

glClear(GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT);
glPushMatrix();
switch(a)
{
case 0:break;
case 1:myDrawCircle();//这两个函数自己写吧~
case 2:myDrawLine();//对,就是这两个~,好久不用了...
//也不知道自己写的对不对,我原来只在VS,VC上用过OPENGL...^_^加油吧~
}
glutSwapBuffers();

}
void main()
{
glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);

glutInitWindowSize(600, 600);
glutInitWindowPosition(0,0);
glutCreateWindow("1");

glutDisplayFunc(RenderScene);
// glutReshapeFunc(ChangeSize);
glutKeyboardFunc(NormalKeys);

SetupRc();
glutMainLoop();
}