OpenGL学习笔记(四)---画动态圆

效果如图：

参考NeHe教程9：

渲染代码：

	#define PI (3.1415926)
	static float ix = 0;
	for (int i = 0; i < 1; i++)
	{
		glLoadIdentity();
		glTranslatef(0.0f, 0.0f, -15.0f);
		
		ix += 0.01f;
		
		//! x' = R * cos(2π/N * x);
		//! Y' = R * sin(2π/N * x);
		glTranslatef(5.0f*cos(2*PI/20 * ix), 5.0f*sin(2*PI/20 * ix), 0.0f);//Coordinate of the circle's x, y;
		glColor4ub(rand() % 256, rand() % 256, rand() % 256, 255);//Change color every frame;
		glBegin(GL_QUADS);
			glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 0.0f);//Render the star pic;
			glTexCoord2f(1.0f, 0.0f); glVertex3f(1.0f, -1.0f, 0.0f);
			glTexCoord2f(1.0f, 1.0f); glVertex3f(1.0f, 1.0f, 0.0f);
			glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f);
		glEnd();
	}