let startAngle = (180 / 13) * (5/2) - 90; // 

let openAngle = 180 / 13; 

​

function setup() {

  createCanvas(500, 500);

  background(200);

}

​

function draw() {

  background(225, 210, 209);

​

  //Set the movement scope

  let triangleNumber = map(mouseX, 30, 450, 1, 9,true); 

​

  // Draw three fans in a row

   fill(201, 44, 34,80);

  drawAFoldingFan(100, height / 2, triangleNumber, startAngle, radius); 

  fill(186, 186, 102);

  drawAFoldingFan(250, height / 2, triangleNumber, startAngle, radius); 

  fill(101, 106, 166);

  drawAFoldingFan(400, height / 2, triangleNumber, startAngle, radius); 

}

​

// Define the drawAFoldingFan function

function drawAFoldingFan(centerX, centerY, triangleNumber, startAngle, radius) {

 push(); 

  translate(centerX, centerY); 

​

  // Draw the specified number of fan leaves

  for (let i = 0; i < triangleNumber; i++) {

    let angleOffset = i * radians(openAngle);

    push();

    rotate(angleOffset + radians(startAngle)); 

    drawFanLeaf(openAngle, radius); 

    pop();

  }

 pop(); // Restore the drawing state after translation

}

​

// Define the function "drawFanLeaf"

function drawFanLeaf(openAngle, radius) {

  let Bx = -radius * tan(radians(openAngle / 2)); //left

  let By = -radius;

  let Cx = radius * tan(radians(openAngle / 2)); //right

  let Cy = -radius;

​

  //Fan leaf model

  beginShape();

  vertex(0, 0); 

  vertex(Bx, By); 

  vertex(Cx, Cy); 

  endShape(CLOSE);

}

​