p5.js uses the draw() function to make a golden spiral-JS Tutorial-php.cn

p5.js uses the draw() function to make a golden spiral

php中世界最好的语言

Release： 2018-06-14 13:46:39

Original

5666 people have browsed it

This time I will show you how to use the draw() function to make a golden spiral in p5.js. What are the precautions for using the draw() function in p5.js to make a golden spiral? Here is a practical case, let’s take a look.

The effect is as follows:

Main method

##translate()
rotate()
arc()

##Fibonacci Spiral

The Fibonacci spiral is also called the "golden spiral". It is a spiral curve drawn based on the Fibonacci number sequence. Draw a 90-degree fan shape in a square with Fibonacci numbers as sides. The connected arcs are Fibonacci spiral.

Sketch

Process Decomposition

1. Define an empty Fibonacci array ：

var Fibonacci = [];

Copy after login

2. Initialization

By default, the draw() function will repeat drawing infinitely, and the frameRate() function can set the number of repeated drawings per second. , like the number of frames per second a movie plays.

function setup(){
 createCanvas(windowWidth, windowHeight);//创建一块画板，画板的宽高与浏览器宽高相同
 background(255);//设置背景颜色为白色
 frameRate(10);//设置每秒10帧
}

Copy after login

3. Set the style of the Fibonacci spiral

function draw(){
 ...
 stroke(0);//线条颜色为黑色
 noFill();//无填充色
 strokeWeight(5);//线条宽度为5
 translate(windowWidth/2, windowHeight/2);//将坐标系移动到页面中央
 ...
}

Copy after login

4. Start drawing the Fibonacci spiral

function draw(){
 ...
 stroke(0);
 noFill();
 strokeWeight(5);
 translate(windowWidth/2, windowHeight/2);
 ...
 for( var i = 0; i < 20; i ++){//绘制20段90度弧线
  var a = i <= 1 ? 1 : Fibonacci[i-1] + Fibonacci[i-2];
//这是条件表达式，如果i等于0或1，那么a等于1；否则等于斐波那契数列前两项的和
  Fibonacci.push(a);//将新得到的a加入斐波那契数列中
  arc(0,0,a * 2,a * 2,0,PI / 2);//绘制圆心在(0,0)直径为2*a度数为90度的弧形
  /**********以下是为下一段弧线做准备************/
  rotate(PI / 2);//将坐标系按顺时针旋转90度
  translate(-Fibonacci[i-1],0); //将坐标系沿着X轴反向移动上一项的长度
 } 
}

Copy after login

5. Let the Fibonacci spiral move

function draw(){
 background(255);//将背景设置成白色，“遮盖”之前的绘图
 stroke(0);
 noFill();
 strokeWeight(5);
 translate(windowWidth/2, windowHeight/2);
 rotate(-PI / 6 * frameCount);//每帧旋转30度，frameCount表示当前已播放帧数
 for( var i = 0; i < 20; i ++){
  var a = i <= 1 ? 1 : Fibonacci[i-1] + Fibonacci[i-2];
  Fibonacci.push(a);
  arc(0,0,a * 2,a * 2,0,PI / 2);
  rotate(PI / 2);
  translate(-Fibonacci[i-1],0); 
 } 
}

Copy after login

Complete code

var Fibonacci = [];
function setup(){
 createCanvas(windowWidth, windowHeight);
 background(255);
 frameRate(10);
}
function draw(){
 background(255);
 stroke(0);
 noFill();
 strokeWeight(5);
 translate(windowWidth/2, windowHeight/2);
 rotate(-PI / 6 * frameCount);
 for( var i = 0; i < 20; i ++){
  var a = i <= 1 ? 1 : Fibonacci[i-1] + Fibonacci[i-2];
  Fibonacci.push(a);
  arc(0,0,a * 2,a * 2,0,PI / 2);
  rotate(PI / 2);
  translate(-Fibonacci[i-1],0); 
 } 
}
function windowResized(){
 resizeCanvas(windowWidth, windowHeight);
}

Copy after login

I believe you have mastered the method after reading the case in this article , for more exciting content, please pay attention to other related articles on the php Chinese website!