OpenGL点光源效果半黑半白

void DrawBackground(GLuint nSize)

{

	glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);

	glColor3f(1.0f,1.0f,1.0f);

	GLint x=-(GLint)nSize/2,y=x;

	GLint width=(GLint)nSize/2,height=width;

	glBegin(GL_QUADS);

	for (int i=x;i<width;i++)

	{

		for (int j=y;j<height;j++)

		{

			glVertex3i(i,0,j);

			glVertex3i(i+1,0,j);

			glVertex3i(i+1,0,j+1);

			glVertex3i(i,0,j+1);

		}

	}

	glEnd();

}

void CMainWnd::DrawScene()

{

	// TODO: Replace the following sample code with your code to draw the scene.

	

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear buffers

	glLoadIdentity(); // Load identity matrix

	

	/*set camera*/

	gluLookAt(0,50,50,0,0,0,0,1,0);



	// Add a light source

	GLfloat glfLightPos[] = {0.0f, 4.0f, 0.0f, 1.0f};//点光源在Y轴正方向上

	glLightfv(GL_LIGHT0, GL_POSITION, glfLightPos);



	/*draw background*/

	DrawBackground(32);//在X轴和Z轴的平面上画一个32x32个小方片组成的幕布，其中心在原点



	glFlush();

}