opengl 如何设置背景色？

[小白也疯狂]

void myTest()
{
	
	glBegin(GL_LINE_LOOP);
	glClearColor(1.0f,1.0f,0.0f,1.0f);  // 把背景色设置为白色，为什么会失败
	glClear(GL_COLOR_BUFFER_BIT);// 背景色一直都是黑色~
	glFlush();
	glColor3f(1,1,0);

	glVertex2f(0.0,0.0);
	glVertex2f(0,0.8);
	glVertex2f(-0.5,0.8);
	glVertex2f(-0.5,-0.9);

	glEnd();	
	glFlush();
}

int main(	int argc,char * argv[] )
{
	glutInit(&argc,argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(200,200);
	glutCreateWindow("My OpenGL");
	glutDisplayFunc(&myTest);
	glutMainLoop();

	return 0 ;
}

[sanss2012]

渲染函数里面, glBegin()应该放在glVertex前面