int r = 50;

void setup() {
  size(600, 600);
}

void draw() {
  background(-1);
  fill(0);

  for (int i = -1; i <= height/r; i++) {
    pushMatrix();
    translate(0, i*r);
    triangleWave();
    popMatrix();
  }
}

void triangleWave() {
  for (int j = 0; j < width; j+=10) {
    float x = j;
    float angle = 10*PI*j/width;
    float y = r*sin(angle + radians(frameCount));

    triangle(x, y);
  }
}


void triangle(float x, float y) {

  pushMatrix();
  translate(x, y);

  beginShape();
  int side_num = 3;
  for (int i = 0; i < side_num; i++) {
    float newR = map(abs(y), r, 0, 5, r/3);
    float pointX = newR * sin(i*TWO_PI/side_num + PI);
    float pointY = newR * cos(i*TWO_PI/side_num + PI);
    vertex(pointX, pointY);
  }

  endShape(CLOSE);
  popMatrix();
}