用processing画李萨如曲线

李萨如曲线

有没有对示波器上变化曲线产生过兴趣，它叫做李萨如曲线：

数学上，利萨茹(Lissajous)曲线（又称利萨茹图形、李萨如图形或鲍迪奇(Bowditch)曲线）是两个沿着互相垂直方向的正弦振动的合成的轨迹

（参见http://zh.wikipedia.org/wiki/%E5%88%A9%E8%90%A8%E8%8C%B9%E6%9B%B2%E7%BA%BF）

代码

//int n=4;
int p=17;
int q=15;

int a = displayWidth /2 ;
int b = a;//displayHeight /2 ;

int radius = 2;
float miu = 0;//PI / 2 / p;
float miu_max = TWO_PI;
float miu_delta = miu_max / 100;

public void setup() {
  size(displayWidth, displayHeight);
  background(0);
  frameRate(2);

  a = displayWidth / 5 ;
  b = a ;
}

public void draw() {

    miu += miu_delta;
    if (miu >= miu_max)
        miu = 0;
//    if (miu >= miu_max)
//    {
//        miu_delta = -miu_delta;
//        miu += miu_delta;
//    }
//    else if (miu < 0)
//    {
//        miu_delta = -miu_delta;
//        miu += miu_delta;
//    }

    fill(0,0,0,250);
    rect(-1,-1, displayWidth+1, displayHeight+1);

    int last_x = -1;
    int last_y = -1;

    for (float theta=0;theta<TWO_PI;theta+=TWO_PI/360)
    {
        int x = (int) (a * sin(p * theta)) + displayWidth /2;
        int y = (int) (b * sin(q * theta + (miu))) + displayHeight /2;

        colorMode(HSB, 255);
        stroke(90, 255, 255);
        fill(90, 255, 255);

        if (last_x != -1 >> last_y != -1)
        {
            line(last_x, last_y, x, y);
            line(last_x-1, last_y, x-1, y);
        }

        last_x = x;
        last_y = y;

        //ellipse(x, y, radius, radius);
    }

}

截图