我已经在canvas html中制作了一个动画，但现在我想让球的原点根据我的鼠标位置在 Canvas 上移动。我想添加鼠标事件功能，但我似乎无法弄清楚逻辑并将其添加到代码中，任何帮助将不胜感激!
function runParticles () {
var canvas = document.createElement("canvas");
c = canvas.getContext("2d");
var particles = {};
var particleIndex = 0;
var particleNum = 15;
// set canvas size
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
// add canvas to body
document.body.appendChild(canvas);
// style the canvas
c.fillStyle = "black";
c.fillRect(0, 0, canvas.width, canvas.height);
function Particle() {
this.x = canvas.width / 2;
this.y = canvas.height / 2;
this.vx = Math.random() * 10 - 5;
this.vy = Math.random() * 10 - 5;
this.gravity = 0.3;
particleIndex++;
particles[particleIndex] = this;
this.id = particleIndex;
this.life = 0;
this.maxLife = Math.random() * 30 + 60;
this.color = "hsla(" + parseInt(Math.random() * 360, 10) + ",90%,60%,0.5";
}
Particle.prototype.draw = function() {
this.x += this.vx;
this.y += this.vy;
if (Math.random() < 0.1) {
this.vx = Math.random() * 10 - 5;
this.vy = Math.random() * 10 - 5;
}
this.life++;
if (this.life >= this.maxLife) {
delete particles[this.id];
}
c.fillStyle = this.color;
//c.fillRect(this.x, this.y, 5, 10);
c.beginPath();
c.arc(this.x, this.y, 2.5, degToRad(0), degToRad(360));
c.fill();
};
setInterval(function() {
//normal setting before drawing over canvas w/ black background
c.globalCompositeOperation = "source-over";
c.fillStyle = "rgba(0,0,0,0.5)";
c.fillRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i < particleNum; i++) {
new Particle();
}
// c.globalCompositeOperation = "darken";
for (var i in particles) {
particles[i].draw();
}
}, 30);
}
function degToRad(deg) {
var radians = (deg * Math.PI / 180) - Math.PI / 2;
return radians;
}<!DOCTYPE html5>
<html>
<head>
<title>disturbed</title>
<script src="toto.js" type="text/javascript"></script>
<script>
window.onload = () => runParticles();
</script>
</head>
<body>
</body>
</html>最佳答案
- 我添加了一个检测鼠标位置的函数:
function oMousePos(canvas, evt) {
var ClientRect = canvas.getBoundingClientRect();
return { //objeto
x: Math.round(evt.clientX - ClientRect.left),
y: Math.round(evt.clientY - ClientRect.top)
}
}
var m = {x:canvas.width/2,y:canvas.height/2};
我已经改变了粒子的起源 this.x = canvas.width/2;
this.y = canvas.height/2; 到 this.x = m.x; this.y = m.y;
这是鼠标不在 Canvas 上移动时的位置
canvas.addEventListener("mousemove", (evt)=>{
m = oMousePos(canvas, evt);
})
我还添加了一个事件“mouseleave”。当鼠标离开 Canvas 时，鼠标回到中心。
canvas.addEventListener("mouseleave", (evt)=>{
m = {x:canvas.width/2,y:canvas.height/2};
})
setInterval (更加高效)。里面的代码就是你的代码。function runParticles () {
var canvas = document.createElement("canvas");
c = canvas.getContext("2d");
var particles = {};
var particleIndex = 0;
var particleNum = 8;
// set canvas size
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
var m = {x:canvas.width/2,y:canvas.height/2};///////
// add canvas to body
document.body.appendChild(canvas);
// style the canvas
c.fillStyle = "black";
c.fillRect(0, 0, canvas.width, canvas.height);
function Particle() {
this.x = m.x;//////////
this.y = m.y;//////////
this.vx = Math.random() * 10 - 5;
this.vy = Math.random() * 10 - 5;
this.gravity = 0.3;
particleIndex++;
particles[particleIndex] = this;
this.id = particleIndex;
this.life = 0;
this.maxLife = Math.random() * 30 + 60;
this.color = "hsla(" + parseInt(Math.random() * 360, 10) + ",90%,60%,0.5";
}
Particle.prototype.draw = function() {
this.x += this.vx;
this.y += this.vy;
if (Math.random() < 0.1) {
this.vx = Math.random() * 10 - 5;
this.vy = Math.random() * 10 - 5;
}
this.life++;
if (this.life >= this.maxLife) {
delete particles[this.id];
}
c.fillStyle = this.color;
//c.fillRect(this.x, this.y, 5, 10);
c.beginPath();
c.arc(this.x, this.y, 2.5, degToRad(0), degToRad(360));
c.fill();
};
function Draw() {
window.requestAnimationFrame(Draw);
c.globalCompositeOperation = "source-over";
c.fillStyle = "rgba(0,0,0,0.5)";
c.fillRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i < particleNum; i++) {
new Particle();
}
// c.globalCompositeOperation = "darken";
for (var i in particles) {
particles[i].draw();
}
}
Draw();
///////////////////
canvas.addEventListener("mousemove", (evt)=>{
m = oMousePos(canvas, evt);
})
canvas.addEventListener("mouseleave", (evt)=>{
m = {x:canvas.width/2,y:canvas.height/2};
})
///////////////////
}
function degToRad(deg) {
var radians = (deg * Math.PI / 180) - Math.PI / 2;
return radians;
}
runParticles();
function oMousePos(canvas, evt) {
var ClientRect = canvas.getBoundingClientRect();
return { //objeto
x: Math.round(evt.clientX - ClientRect.left),
y: Math.round(evt.clientY - ClientRect.top)
}
}body,canvas{margin:0;padding:0;}我希望这会有所帮助。
关于javascript - 将鼠标移动添加到 Canvas 动画，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/52481111/