我一直在尝试在画布和Javascript中重新创建this Project。我无法解密原始代码,所以我从头开始了。区别在于,我的项目开始滞后于大约2500个粒子,而上述项目的工作量为30000。
我将在下面粘贴我的整个代码,但这是相关的部分:
var particleContainer = []
var distance = 10
for(let i = 0; i< square.height/distance; i++){
for(let j = 0; j< square.height/distance; j++){
particleContainer.push( new Particle(square.x + i*distance,square.y + j*distance) )
}
}
if( c < 90 ){
i.xVelocity = a/c * -20
i.yVelocity = b/c * -20
}else if(90 < c && c < 95){
i.xVelocity = a/c * -1
i.yVelocity = b/c * -1
}else if(c2 !== 0){
i.xVelocity =( a2/c2 )
i.yVelocity = (b2/c2 )
}
我要在正方形的每个“距离”像素处创建一个新的粒子,并将它们全部推入数组。当我的鼠标靠近其中之一时,粒子将开始远离鼠标移动,直到距离鼠标90-95px。
从这行来看,30000像素似乎以类似的方式工作
for ( i = 0; i < NUM_PARTICLES; i++ ) {
p = Object.create( particle );
p.x = p.ox = MARGIN + SPACING * ( i % COLS );
p.y = p.oy = MARGIN + SPACING * Math.floor( i / COLS );
list[i] = p;
}
但是该项目不会遇到与我一样的性能问题。
我的完整代码供参考,(html只是一个画布):
var canvas = document.querySelector("canvas")
var c = canvas.getContext('2d')
function getMousePos(canvas, evt) {
// var rect = canvas.getBoundingClientRect();
return {
x: evt.clientX,
y: evt.clientY
};
}
document.addEventListener('mousemove', function(evt) {
var mousePos = getMousePos(canvas, evt);
mouse.x= mousePos.x;
mouse.y= mousePos.y;
}, false);
var mouse = {
x:0,
y:0
}
function Particle(x,y){
this.x = x;
this.y = y;
this.xFixed = x;
this.yFixed = y;
this.radius = 1
this.xVelocity = 0
this.yVelocity = 0
this.color = 'white'
}
Particle.prototype.draw = function(){
c.save()
c.beginPath()
c.arc(this.x, this.y, this.radius,0,Math.PI*2,false)
c.fillStyle = this.color
c.fill()
}
Particle.prototype.update = function(){
this.draw()
this.x += this.xVelocity
this.y += this.yVelocity
}
var square = {
x: 500,
y: 150,
height: 500,
width: 500,
color: 'white'
}
var particleContainer = []
var distance = 10
for(let i = 0; i< square.height/distance; i++){
for(let j = 0; j< square.height/distance; j++){
particleContainer.push( new Particle(square.x + i*distance,square.y + j*distance) )
}
}
function animate(){
requestAnimationFrame(animate);
c.clearRect(0,0,window.innerWidth,window.innerHeight)
canvas.width = window.innerWidth
canvas.height = window.innerHeight
for(i of particleContainer){
let a = mouse.x - i.x
let b = mouse.y - i.y
let c = Math.sqrt(Math.pow(b,2) + Math.pow(a,2))
let a2 = i.xFixed - i.x
let b2 = i.yFixed - i.y
let c2 = Math.sqrt(Math.pow(b2,2) + Math.pow(a2,2))
if( c < 90 ){
i.xVelocity = a/c * -20
i.yVelocity = b/c * -20
}else if(90 < c && c < 95){
i.xVelocity = a/c * -1
i.yVelocity = b/c * -1
}else if(c2 !== 0){
i.xVelocity =( a2/c2 )
i.yVelocity = (b2/c2 )
}
}
for(i of particleContainer){
i.update()
}
}
animate()
答案 0 :(得分:1)
了解如何在开发工具中使用“效果”标签,然后可以查看哪些功能花费的时间最多。在这种情况下,我认为您会看到它是ctx.fill
。您发布的示例是将像素写入ImageData
缓冲区,这比绘制和填充弧要快得多。示例中还有很多其他小的优化,但这将是最重要的优化,图纸通常比更新慢得多。
答案 1 :(得分:1)
要获得更好的渲染,您需要将渲染对象添加到同一路径。创建路径后,您可以一次调用ctx.fill
尝试限制对innerWidth
和innerHeight
的访问,因为它们是非常慢的DOM对象,可能仅通过访问它们就导致重排。
可以通过使用对象池和预分配来进行进一步的改进,但这超出了单个答案的范围。
对动画功能进行以下更改。
var W = 1, H = 1;
function animate() {
requestAnimationFrame(animate);
c.clearRect(0 ,0, W, H)
if (H !== innerHeight || W !== innerWidth) {
W = canvas.width = innerWidth;
H = canvas.height = innerHeight;
}
c.beginPath(); // start a new path
c.fillStyle = "white";
for (i of particleContainer) { // update and draw all particles in one pass
const a = mouse.x - i.x, b = mouse.y - i.y
const c = (b * b + a * a) ** 0.5;
const a2 = i.xFixed - i.x, b2 = i.yFixed - i.y
const c2 = (b2 * b2 + a2 * a2) ** 0.5;
if( c < 90 ){
i.x += a/c * -20
i.y += b/c * -20
}else if(90 < c && c < 95){
i.x += a/c * -1
i.y += b/c * -1
}else if(c2 !== 0){
i.x +=( a2/c2 )
i.y += (b2/c2 )
}
c.rect(i.x, i.y, 1,1);
}
c.fill(); // path complete render it.
//for(i of particleContainer){ // no longer needed
// i.update()
//}
}