原理即將一條曲線分割成多個線段，以顯示成曲線的樣子。

void drawCurves(CCPoint p0, CCPoint p1, void (*drawFunc)(CCPoint, CCPoint))
{
#define kSegmentWidth 8
	int segment = floorf((p1.x - p0.x) / kSegmentWidth);
	//兩點y座標的中間點
	float yMid = (p1.y + p0.y) / 2;
	//兩點在y軸上的距離的一半
	float ampl = (p1.y - p0.y) / 2;
	CCPoint pt0, pt1;
	float dx = (p1.x - p0.x)/segment;

	pt0 = p0;
	//曲線的點的運算皆需要以(p0.x, yMid)為參照
	for(int i = 0; i < segment + 1; i++)
	{
		pt1.x = p0.x + i * dx;
		pt1.y = yMid + ampl * cosf(M_PI * i /segment); 
		drawFunc(pt0, pt1);
		pt0 = pt1;
	}
}