p5.js入门教程之鼠标交互的示例

function setup() {  
 createCanvas(400, 400); 
}  
function draw() {  
 background(220); 
 if (mouseIsPressed) { 
  textAlign(CENTER); 
  textSize(30); 
  if (mouseButton == LEFT) 
   text("LEFT",200,height/2); 
  if (mouseButton == RIGHT) 
   text("RIGHT",200,height/2); 
  if (mouseButton == CENTER) 
   text("CENTER",200,height/2); 
 } 
} 

var showEllipse=false; 
var showRect=false; 
function setup() {  
 createCanvas(400, 400); 
}  
function draw() {  
 background(220); 
 if (mouseIsPressed){ 
  ellipse(50, height/2, 50, 50); 
 } 
 if(showEllipse){ 
    ellipse(200, height/2, 50, 50); 
 } 
 if(showRect){ 
  rectMode(CENTER); 
  rect(350,height/2,50,50);  
 } 
} 
function mouseClicked(){ 
 showEllipse=!showEllipse; 
} 
 
function mousePressed(){ 
 showRect=true; 
} 
function mouseReleased(){ 
 showRect=false; 
} 

var x=200; 
var y=200 
var r=50; 
function setup() {  
 createCanvas(400, 400); 
}  
 
function draw() {  
 background(220); 
 if(mouseIsPressed&&dist(mouseX,mouseY,x,y)<r){ 
  x=mouseX; 
  y=mouseY; 
 } 
 ellipse(x,y,r,r); 
}