canvas绚丽曲线
<!--index.html -->
<html>
<body>
<canvas id="canvas" width="100%" height="100%"
style="position: fixed;top: 0;bottom: 0;left: 0;right: 0;background: #000000;"></canvas>
</body>
<script type="text/javascript" charset="utf-8" src="./js/canvas.js"></script>
</html>
// canvas.js
var Stats = function () {
var e = Date.now(),
t = e,
i = 0,
n = 1 / 0,
r = 0,
s = 0,
o = 1 / 0,
a = 0,
l = 0,
h = 0,
c = document.createElement("div");
(c.id = "stats"),
c.addEventListener(
"mousedown",
function (e) {
e.preventDefault(), v(++h % 2);
},
!1
),
(c.style.cssText = "width:80px;opacity:0.9;cursor:pointer");
var u = document.createElement("div");
(u.id = "fps"),
(u.style.cssText =
"padding:0 0 3px 3px;text-align:left;background-color:#002"),
c.appendChild(u);
var d = document.createElement("div");
(d.id = "fpsText"),
(d.style.cssText =
"color:#0ff;font-family:Helvetica,Arial,sans-serif;font-size:9px;font-weight:bold;line-height:15px"),
(d.innerHTML = "FPS"),
u.appendChild(d);
var p = document.createElement("div");
for (
p.id = "fpsGraph",
p.style.cssText =
"position:relative;width:74px;height:30px;background-color:#0ff",
u.appendChild(p);
74 > p.children.length;
) {
var f = document.createElement("span");
(f.style.cssText =
"width:1px;height:30px;float:left;background-color:#113"),
p.appendChild(f);
}
var m = document.createElement("div");
(m.id = "ms"),
(m.style.cssText =
"padding:0 0 3px 3px;text-align:left;background-color:#020;display:none"),
c.appendChild(m);
var g = document.createElement("div");
(g.id = "msText"),
(g.style.cssText =
"color:#0f0;font-family:Helvetica,Arial,sans-serif;font-size:9px;font-weight:bold;line-height:15px"),
(g.innerHTML = "MS"),
m.appendChild(g);
var y = document.createElement("div");
for (
y.id = "msGraph",
y.style.cssText =
"position:relative;width:74px;height:30px;background-color:#0f0",
m.appendChild(y);
74 > y.children.length;
) {
var f = document.createElement("span");
(f.style.cssText =
"width:1px;height:30px;float:left;background-color:#131"),
y.appendChild(f);
}
var v = function (e) {
switch ((h = e)) {
case 0:
(u.style.display = "block"), (m.style.display = "none");
break;
case 1:
(u.style.display = "none"), (m.style.display = "block");
}
},
b = function (e, t) {
var i = e.appendChild(e.firstChild);
i.style.height = t + "px";
};
return {
REVISION: 11,
domElement: c,
setMode: v,
begin: function () {
e = Date.now();
},
end: function () {
var h = Date.now();
return (
(i = h - e),
(n = Math.min(n, i)),
(r = Math.max(r, i)),
(g.textContent = i + " MS (" + n + "-" + r + ")"),
b(y, Math.min(30, 30 - 30 * (i / 200))),
l++,
h > t + 1000 &&
((s = Math.round((1000 * l) / (h - t))),
(o = Math.min(o, s)),
(a = Math.max(a, s)),
(d.textContent = s + " FPS (" + o + "-" + a + ")"),
b(p, Math.min(30, 30 - 30 * (s / 100))),
(t = h),
(l = 0)),
h
);
},
update: function () {
e = this.end();
},
};
};
(function (window) {
var ctx,
hue,
logo,
form,
buffer,
target = {},
tendrils = [],
settings = {};
settings.debug = true;
settings.friction = 0.5;
settings.trails = 20;
settings.size = 50;
settings.dampening = 0.25;
settings.tension = 0.98;
Math.TWO_PI = Math.PI * 2;
function Oscillator(options) {
this.init(options || {});
}
Oscillator.prototype = (function () {
var value = 0;
return {
init: function (options) {
this.phase = options.phase || 0;
this.offset = options.offset || 0;
this.frequency = options.frequency || 0.001;
this.amplitude = options.amplitude || 1;
},
update: function () {
this.phase += this.frequency;
value = this.offset + Math.sin(this.phase) * this.amplitude;
return value;
},
value: function () {
return value;
},
};
})();
function Tendril(options) {
this.init(options || {});
}
Tendril.prototype = (function () {
function Node() {
this.x = 0;
this.y = 0;
this.vy = 0;
this.vx = 0;
}
return {
init: function (options) {
this.spring = options.spring + Math.random() * 0.1 - 0.05;
this.friction = settings.friction + Math.random() * 0.01 - 0.005;
this.nodes = [];
for (var i = 0, node; i < settings.size; i++) {
node = new Node();
node.x = target.x;
node.y = target.y;
this.nodes.push(node);
}
},
update: function () {
var spring = this.spring,
node = this.nodes[0];
node.vx += (target.x - node.x) * spring;
node.vy += (target.y - node.y) * spring;
for (var prev, i = 0, n = this.nodes.length; i < n; i++) {
node = this.nodes[i];
if (i > 0) {
prev = this.nodes[i - 1];
node.vx += (prev.x - node.x) * spring;
node.vy += (prev.y - node.y) * spring;
node.vx += prev.vx * settings.dampening;
node.vy += prev.vy * settings.dampening;
}
node.vx *= this.friction;
node.vy *= this.friction;
node.x += node.vx;
node.y += node.vy;
spring *= settings.tension;
}
},
draw: function () {
var x = this.nodes[0].x,
y = this.nodes[0].y,
a,
b;
ctx.beginPath();
ctx.moveTo(x, y);
for (var i = 1, n = this.nodes.length - 2; i < n; i++) {
a = this.nodes[i];
b = this.nodes[i + 1];
x = (a.x + b.x) * 0.5;
y = (a.y + b.y) * 0.5;
ctx.quadraticCurveTo(a.x, a.y, x, y);
}
a = this.nodes[i];
b = this.nodes[i + 1];
ctx.quadraticCurveTo(a.x, a.y, b.x, b.y);
ctx.stroke();
ctx.closePath();
},
};
})();
function init(event) {
document.removeEventListener("mousemove", init);
document.removeEventListener("touchstart", init);
document.addEventListener("mousemove", mousemove);
document.addEventListener("touchmove", mousemove);
document.addEventListener("touchstart", touchstart);
mousemove(event);
reset();
loop();
}
function reset() {
tendrils = [];
for (var i = 0; i < settings.trails; i++) {
tendrils.push(
new Tendril({ spring: 0.45 + 0.025 * (i / settings.trails) })
);
}
}
function loop() {
if (!ctx.running) {
return;
}
ctx.globalCompositeOperation = "source-over";
ctx.fillStyle = "rgba(8,5,16,0.4)";
ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
ctx.globalCompositeOperation = "lighter";
ctx.strokeStyle = "hsla(" + Math.round(hue.update()) + ",90%,50%,0.25)";
ctx.lineWidth = 1;
if (ctx.frame % 60 == 0) {
}
for (var i = 0, tendril; i < settings.trails; i++) {
tendril = tendrils[i];
tendril.update();
tendril.draw();
}
ctx.frame++;
ctx.stats.update();
requestAnimFrame(loop);
}
function resize() {
ctx.canvas.width = window.innerWidth;
ctx.canvas.height = window.innerHeight;
}
function start() {
if (!ctx.running) {
ctx.running = true;
loop();
}
}
function stop() {
ctx.running = false;
}
function mousemove(event) {
if (event.touches) {
target.x = event.touches[0].pageX;
target.y = event.touches[0].pageY;
} else {
target.x = event.clientX;
target.y = event.clientY;
}
event.preventDefault();
}
function touchstart(event) {
if (event.touches.length == 1) {
target.x = event.touches[0].pageX;
target.y = event.touches[0].pageY;
}
}
function keyup(event) {
switch (event.keyCode) {
case 32:
save();
break;
default:
}
}
function letters(id) {
var el = document.getElementById(id),
letters = el.innerHTML.replace("&", "&").split(""),
heading = "";
for (var i = 0, n = letters.length, letter; i < n; i++) {
letter = letters[i].replace("&", "&");
heading += letter.trim()
? '<span class="letter-' + i + '">' + letter + "</span>"
: " ";
}
el.innerHTML = heading;
setTimeout(function () {
el.className = "transition-in";
}, Math.random() * 500 + 500);
}
function save() {
if (!buffer) {
buffer = document.createElement("canvas");
buffer.width = screen.availWidth;
buffer.height = screen.availHeight;
buffer.ctx = buffer.getContext("2d");
form = document.createElement("form");
form.method = "post";
form.input = document.createElement("input");
form.input.type = "hidden";
form.input.name = "data";
form.appendChild(form.input);
document.body.appendChild(form);
}
buffer.ctx.fillStyle = "rgba(8,5,16)";
buffer.ctx.fillRect(0, 0, buffer.width, buffer.height);
buffer.ctx.drawImage(
canvas,
Math.round(buffer.width / 2 - canvas.width / 2),
Math.round(buffer.height / 2 - canvas.height / 2)
);
buffer.ctx.drawImage(
logo,
Math.round(buffer.width / 2 - logo.width / 4),
Math.round(buffer.height / 2 - logo.height / 4),
logo.width / 2,
logo.height / 2
);
window.open(
buffer.toDataURL(),
"wallpaper",
"top=0,left=0,width=" + buffer.width + ",height=" + buffer.height
);
}
window.requestAnimFrame = (function () {
return (
window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
function (fn) {
window.setTimeout(fn, 1000 / 60);
}
);
})();
window.onload = function () {
ctx = document.getElementById("canvas").getContext("2d");
ctx.stats = new Stats();
ctx.running = true;
ctx.frame = 1;
hue = new Oscillator({
phase: Math.random() * Math.TWO_PI,
amplitude: 85,
frequency: 0.0015,
offset: 285,
});
document.addEventListener("mousemove", init);
document.addEventListener("touchstart", init);
document.body.addEventListener("orientationchange", resize);
window.addEventListener("resize", resize);
window.addEventListener("keyup", keyup);
window.addEventListener("focus", start);
window.addEventListener("blur", stop);
resize();
if (window.DEBUG) {
var gui = new dat.GUI();
settings.gui.add(settings, "trails", 1, 30).onChange(reset);
settings.gui.add(settings, "size", 25, 75).onFinishChange(reset);
settings.gui.add(settings, "friction", 0.45, 0.55).onFinishChange(reset);
settings.gui.add(settings, "dampening", 0.01, 0.4).onFinishChange(reset);
settings.gui.add(settings, "tension", 0.95, 0.999).onFinishChange(reset);
document.body.appendChild(ctx.stats.domElement);
}
};
})(window);
