帆布火花线
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我想创建一个具有各种长度的火花线,并通过从画布的中心移动到画布的末端来动画它们,并且该过程必须在画布上循环。为了达到这个目的,我开始使用粒子系统。
请检查以下代码,这里是codepen链接https://codepen.io/yesvin/pen/XPKNYW
window.onload = function() {
var canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
w = canvas.width = window.innerWidth,
h = canvas.height = window.innerHeight,
centerX = w / 2,
centerY = h / 2,
speed = 0,
time = 0,
numObjects = 5,
x, y, vx, vy, life, maxLife;
var lines = {},
lineIndex = 0;
function Line() {
this.x = centerX;
this.y = centerY;
this.vx = Math.random() * 16 - 8;
this.vy = Math.random() * 16 - 8;
this.life = 0;
this.maxLife = Math.random() * 10 + 20;
lineIndex++;
lines[lineIndex] = this;
this.id = lineIndex;
}
Line.prototype.draw = function() {
this.x += this.vx;
this.y += this.vy;
this.life++;
if (this.life >= this.maxLife) {
delete lines[this.id];
}
context.fillStyle = "#000";
context.fillRect(this.x, this.y, 3, 3)
}
setInterval(function() {
context.fillStyle = 'rgba(255,255,255,.05)';
context.fillRect(0, 0, w, h);
new Line();
for (var i in lines) {
lines[i].draw();
}
}, 30)
};
body {
overflow: hidden;
margin: 0;
padding: 0;
}
canvas {
display: block;
}
<canvas id="canvas"></canvas>
那么,我们如何使用lineTo()
和moveTo()
方法创建相同的效果?我尝试使用以下代码(在codepen中注释)
context.beginPath();
context.moveTo(centerX, centerY);
context.lineTo(this.x * Math.random() * w, this.y * Math.random() * h);
context.lineWidth = 1;
context.stroke();
context.strokeStyle = "#000";
提前致谢。
答案
这是一种方法...... 使用线条,您将获得更持续的效果:
我对您的代码所做的更改是跟踪起点和终点。
window.onload = function() {
var canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
w = canvas.width = window.innerWidth,
h = canvas.height = window.innerHeight,
centerX = w / 2,
centerY = h / 2;
var lines = {},
lineIndex = 0;
function Line() {
this.start = { x: centerX, y: centerY };
this.end = { x: centerX, y: centerY };
this.vx = Math.random() * 16 - 8;
this.vy = Math.random() * 16 - 8;
this.life = 0;
this.maxLife = Math.random() * 10 + 20;
lineIndex++;
lines[lineIndex] = this;
this.id = lineIndex;
}
Line.prototype.draw = function() {
this.end.x += this.vx;
this.end.y += this.vy;
this.life++;
if (this.life >= this.maxLife) {
delete lines[this.id];
}
//context.fillStyle = "#000";
//context.fillRect(this.x, this.y, 1, 1)
context.beginPath();
context.moveTo(this.start.x, this.start.y);
context.lineTo(this.end.x, this.end.y);
context.lineWidth = 1;
context.stroke();
context.strokeStyle = "#000";
}
setInterval(function() {
context.fillStyle = 'rgba(255,255,255,.05)';
context.fillRect(0, 0, w, h);
new Line();
for (var i in lines) {
lines[i].draw();
}
}, 30)
};
body {
overflow: hidden;
margin: 0;
padding: 0;
}
canvas {
display: block;
}
<canvas id="canvas"></canvas>
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