在数组p5.js中分别更改每个形状的不透明度

let shapes = [];

function setup() {
  createCanvas(400, 400);
  
  // 创建一系列形状
  for(let i = 0; i < 10; i++) {
    let x = random(width);
    let y = random(height);
    let size = random(50, 100);
    let opacity = random(255);
    let shape = createShape(x, y, size, opacity);
    shapes.push(shape);
  }
}

function draw() {
  background(220);
  
  // 更新和绘制每个形状
  for(let i = 0; i < shapes.length; i++) {
    let shape = shapes[i];
    
    // 更改不透明度
    let opacity = random(255);
    shape.alpha(opacity);
    
    // 绘制形状
    shape.draw();
  }
}

// 创建一个形状对象
function createShape(x, y, size, opacity) {
  let shape = {
    x: x,
    y: y,
    size: size,
    opacity: opacity,
    
    // 更改不透明度
    alpha: function(opacity) {
      this.opacity = opacity;
    },
    
    // 绘制形状
    draw: function() {
      fill(255, this.opacity);
      rect(this.x, this.y, this.size, this.size);
    }
  };
  
  return shape;
}