processing模拟三角级数合成方波过程

代码

int radius = 2;
int[] accumys;
int times = 0;

float scale = 1;
int origin = 400;

float factor = 1;

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

  accumys = new int[displayWidth];

  for(int i=0;i<displayWidth;i++)
  {
      accumys[i] = 0;
  }

  scale = 1;
  origin = displayHeight / 2;

  factor = (PI * 3/ displayWidth );
}

public void draw() {

    fill(0,0,0,50);
    rect(-1,-1,displayWidth + 1, displayHeight+1);

    float k = ++times;
    int last_y = 0;
    for (int i=0;i<displayWidth;i++)
    {
        float t = i;
        float up = sin((2 * k - 1) * factor * t);
        float down = (2 * k - 1) * factor;

        accumys[i] += (int) ((float)4 * up / (PI * down));

        if (i >= 1)
        {
            colorMode(HSB, 255);
            stroke(90, 255, 255);
            line(i-1, last_y * scale + origin, i, accumys[i] * scale + origin);
            line(i, last_y * scale + origin, i+1, accumys[i] * scale + origin);
        }

        last_y = accumys[i];
    }

}

截图