GDI绘制叶形线和蝴蝶结

具有一定规律的曲线可以用数学表达式来模拟，那么在计算机世界中这些图形是怎么生成的，下面来看一下一些简单图形的生成方法，蝴蝶线和星形线。

蝴蝶线、代码如下：

void OnDrawRose(CDC* pDc)
{
	int d,k,x1,x2,y1,y2;
	float pi,a,e;
	CPen pen;
	pen.CreatePen(PS_SOLID,1,RGB(0xff,0,0));
	CPen *pOldPen = pDc->SelectObject(&pen);
	pi = 3.1415926;
	d = 80;
	for (a = 0; a<=2 * pi; a+= pi/360)
	{
		e = d * (1+0.25*sin(4*a));
		e = e * (1 + sin(8*a));
		x1 = int(320+e*cos(a));
		x2 = int(320+e*cos(a + pi/8));
		y1 = int(200+e*sin(a));
		y2 = int(200+e*sin(a + pi/8));
		pDc->MoveTo(x1,y1);
		pDc->LineTo(x2,y2);
	}
}

星形线的绘制代码如下：

void OnDrawLeaf(CDC* pDc)
{
	CPen pen;
	pen.CreatePen(PS_SOLID,1,RGB(0,0,0xff));
	CPen *pOldPen = pDc->SelectObject(&pen);

	int a,n,cx,cy,gx,gy,flag,k;
	double r,p,th,x,y,pi;
	a = 160;n = 2;pi = 3.1415926;
	cx = 700;
	cy = 500;
	flag = 0; k = 200;
	for (p = 1; p >= 0.2; p-=0.2)
	{
		for (th = 0; th <= 2*pi+0.1; th += pi/k)
		{
			r = fabs(a*cos(n*th)*p);
			x = r*cos(th);
			y = r*sin(th);
			gx = int(cx+x);
			gy = int(cy+y);
			if (flag == 0)
			{
				pDc->MoveTo(gx,gy);
			}
			flag = 1;
			pDc->LineTo(gx,gy);
		}
		flag = 0;
	}
	pDc->SelectObject(pOldPen);
}

生产成的图形如下：

呵呵，效果还可以吧