之前记录过一个挺炫的开场动画，把相关代码贴出来，喜欢的可以用用，效果见本站。
具体来源记不清了。
第一步：设置 CSS
#canvas-container {
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
width: 100%;
height: 100%;
background: #000;
z-index: 99999;
}第二步，把下面 JavaScript 放到页面里
var S = {
init: function() {
S.Drawing.init();
S.UI.simulate("哈哈|欢迎来到|X柏放的小巢|#countdown 3");
S.Drawing.loop(function() {
S.Shape.render();
});
},
destroy: function() {
S.Drawing.destroy();
}
};
S.Drawing = (function() {
var canvasContainer,
canvas,
context,
renderFn,
requestFrameId,
requestFrame =
window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
return {
init: function(el) {
this.createDOMNode();
context = canvas.getContext("2d");
this.adjustCanvas();
window.addEventListener("resize", function(e) {
S.Drawing.adjustCanvas();
});
},
createDOMNode: function() {
canvasContainer = document.createElement("div");
canvasContainer.id = 'canvas-container';
canvas = document.createElement('canvas');
canvas.width = '100%';
canvas.height = '100%';
canvasContainer.appendChild(canvas);
document.querySelector('body').append(canvasContainer);
},
loop: function(fn) {
renderFn = !renderFn ? fn : renderFn;
this.clearFrame();
renderFn();
requestFrameId = requestFrame.call(window, this.loop.bind(this));
},
adjustCanvas: function() {
canvas.width = window.innerWidth - 100;
canvas.height = window.innerHeight - 30;
},
clearFrame: function() {
context.clearRect(0, 0, canvas.width, canvas.height);
},
getArea: function() {
return {
w: canvas.width,
h: canvas.height
};
},
drawCircle: function(p, c) {
context.fillStyle = c.render();
context.beginPath();
context.arc(p.x, p.y, p.z, 0, 2 * Math.PI, true);
context.closePath();
context.fill();
},
destroy: function() {
canvasContainer.parentNode.removeChild(canvasContainer);
window.cancelAnimationFrame(requestFrameId);
window.removeEventListener('resize', function() {
S.Drawing.adjustCanvas();
});
}
};
})();
S.UI = (function() {
var interval,
currentAction,
time,
maxShapeSize = 30,
sequence = [],
cmd = "#";
function formatTime(date) {
var h = date.getHours(),
m = date.getMinutes(),
m = m < 10 ? "0" + m : m;
return h + ":" + m;
}
function getValue(value) {
return value && value.split(" ")[1];
}
function getAction(value) {
value = value && value.split(" ")[0];
return value && value[0] === cmd && value.substring(1);
}
function timedAction(fn, delay, max, reverse) {
clearInterval(interval);
currentAction = reverse ? max : 1;
fn(currentAction);
if (
!max ||
(!reverse && currentAction < max) ||
(reverse && currentAction > 0)
) {
interval = setInterval(function() {
currentAction = reverse ? currentAction - 1 : currentAction + 1;
fn(currentAction);
if (
(!reverse && max && currentAction === max) ||
(reverse && currentAction === 0)
) {
clearInterval(interval);
}
}, delay);
}
}
function performAction(value) {
var action, value, current;
sequence =
typeof value === "object" ?
value :
sequence.concat(value.split("|"));
timedAction(
function(index) {
current = sequence.shift();
action = getAction(current);
value = getValue(current);
switch (action) {
case "countdown":
value = parseInt(value) || 10;
value = value > 0 ? value : 10;
timedAction(
function(index) {
if (index === 0) {
if (sequence.length === 0) {
S.Shape.switchShape(S.ShapeBuilder.letter(''));
window.setTimeout(function() {
S.destroy();
}, 600);
} else {
performAction(sequence);
}
} else {
S.Shape.switchShape(S.ShapeBuilder.letter(index), true);
}
},
1000,
value,
true
);
break;
case "rectangle":
value = value && value.split("x");
value =
value && value.length === 2 ?
value : [maxShapeSize, maxShapeSize / 2];
S.Shape.switchShape(
S.ShapeBuilder.rectangle(
Math.min(maxShapeSize, parseInt(value[0])),
Math.min(maxShapeSize, parseInt(value[1]))
)
);
break;
case "circle":
value = parseInt(value) || maxShapeSize;
value = Math.min(value, maxShapeSize);
S.Shape.switchShape(S.ShapeBuilder.circle(value));
break;
case "time":
var t = formatTime(new Date());
if (sequence.length > 0) {
S.Shape.switchShape(S.ShapeBuilder.letter(t));
} else {
timedAction(function() {
t = formatTime(new Date());
if (t !== time) {
time = t;
S.Shape.switchShape(S.ShapeBuilder.letter(time));
}
}, 1000);
}
break;
default:
S.Shape.switchShape(
S.ShapeBuilder.letter(
current[0] === cmd ? "HacPai" : current
)
);
}
},
2000,
sequence.length
);
}
return {
simulate: function(action) {
performAction(action);
},
};
})();
S.Point = function(args) {
this.x = args.x;
this.y = args.y;
this.z = args.z;
this.a = args.a;
this.h = args.h;
};
S.Color = function(r, g, b, a) {
this.r = r;
this.g = g;
this.b = b;
this.a = a;
};
S.Color.prototype = {
render: function() {
return (
"rgba(" + this.r + "," + +this.g + "," + this.b + "," + this.a + ")"
);
},
};
S.Dot = function(x, y) {
this.p = new S.Point({
x: x,
y: y,
z: 5,
a: 1,
h: 0,
});
this.e = 0.07;
this.s = true;
this.c = new S.Color(255, 255, 255, this.p.a);
this.t = this.clone();
this.q = [];
};
S.Dot.prototype = {
clone: function() {
return new S.Point({
x: this.x,
y: this.y,
z: this.z,
a: this.a,
h: this.h,
});
},
_draw: function() {
this.c.a = this.p.a;
S.Drawing.drawCircle(this.p, this.c);
},
_moveTowards: function(n) {
var details = this.distanceTo(n, true),
dx = details[0],
dy = details[1],
d = details[2],
e = this.e * d;
if (this.p.h === -1) {
this.p.x = n.x;
this.p.y = n.y;
return true;
}
if (d > 1) {
this.p.x -= (dx / d) * e;
this.p.y -= (dy / d) * e;
} else {
if (this.p.h > 0) {
this.p.h--;
} else {
return true;
}
}
return false;
},
_update: function() {
if (this._moveTowards(this.t)) {
var p = this.q.shift();
if (p) {
this.t.x = p.x || this.p.x;
this.t.y = p.y || this.p.y;
this.t.z = p.z || this.p.z;
this.t.a = p.a || this.p.a;
this.p.h = p.h || 0;
} else {
if (this.s) {
this.p.x -= Math.sin(Math.random() * 3.142);
this.p.y -= Math.sin(Math.random() * 3.142);
} else {
this.move(
new S.Point({
x: this.p.x + Math.random() * 50 - 25,
y: this.p.y + Math.random() * 50 - 25,
})
);
}
}
}
d = this.p.a - this.t.a;
this.p.a = Math.max(0.1, this.p.a - d * 0.05);
d = this.p.z - this.t.z;
this.p.z = Math.max(1, this.p.z - d * 0.05);
},
distanceTo: function(n, details) {
var dx = this.p.x - n.x,
dy = this.p.y - n.y,
d = Math.sqrt(dx * dx + dy * dy);
return details ? [dx, dy, d] : d;
},
move: function(p, avoidStatic) {
if (!avoidStatic || (avoidStatic && this.distanceTo(p) > 1)) {
this.q.push(p);
}
},
render: function() {
this._update();
this._draw();
},
};
S.ShapeBuilder = (function() {
var gap = 13,
shapeCanvas = document.createElement("canvas"),
shapeContext = shapeCanvas.getContext("2d"),
fontSize = 500,
fontFamily = "Avenir, Helvetica Neue, Helvetica, Arial, sans-serif";
function fit() {
shapeCanvas.width = Math.floor(window.innerWidth / gap) * gap;
shapeCanvas.height = Math.floor(window.innerHeight / gap) * gap;
shapeContext.fillStyle = "red";
shapeContext.textBaseline = "middle";
shapeContext.textAlign = "center";
}
function processCanvas() {
var pixels = shapeContext.getImageData(
0,
0,
shapeCanvas.width,
shapeCanvas.height
).data;
(dots = []),
pixels,
(x = 0),
(y = 0),
(fx = shapeCanvas.width),
(fy = shapeCanvas.height),
(w = 0),
(h = 0);
for (var p = 0; p < pixels.length; p += 4 * gap) {
if (pixels[p + 3] > 0) {
dots.push(
new S.Point({
x: x,
y: y,
})
);
w = x > w ? x : w;
h = y > h ? y : h;
fx = x < fx ? x : fx;
fy = y < fy ? y : fy;
}
x += gap;
if (x >= shapeCanvas.width) {
x = 0;
y += gap;
p += gap * 4 * shapeCanvas.width;
}
}
return {
dots: dots,
w: w + fx,
h: h + fy
};
}
function setFontSize(s) {
shapeContext.font = "bold " + s + "px " + fontFamily;
}
function isNumber(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
function init() {
fit();
window.addEventListener("resize", fit);
}
// Init
init();
return {
imageFile: function(url, callback) {
var image = new Image(),
a = S.Drawing.getArea();
image.onload = function() {
shapeContext.clearRect(
0,
0,
shapeCanvas.width,
shapeCanvas.height
);
shapeContext.drawImage(this, 0, 0, a.h * 0.6, a.h * 0.6);
callback(processCanvas());
};
image.onerror = function() {
callback(S.ShapeBuilder.letter("What?"));
};
image.src = url;
},
circle: function(d) {
var r = Math.max(0, d) / 2;
shapeContext.clearRect(0, 0, shapeCanvas.width, shapeCanvas.height);
shapeContext.beginPath();
shapeContext.arc(r * gap, r * gap, r * gap, 0, 2 * Math.PI, false);
shapeContext.fill();
shapeContext.closePath();
return processCanvas();
},
letter: function(l) {
var s = 0;
setFontSize(fontSize);
s = Math.min(
fontSize,
(shapeCanvas.width / shapeContext.measureText(l).width) *
0.8 *
fontSize,
(shapeCanvas.height / fontSize) *
(isNumber(l) ? 1 : 0.45) *
fontSize
);
setFontSize(s);
shapeContext.clearRect(0, 0, shapeCanvas.width, shapeCanvas.height);
shapeContext.fillText(
l,
shapeCanvas.width / 2,
shapeCanvas.height / 2
);
return processCanvas();
},
rectangle: function(w, h) {
var dots = [],
width = gap * w,
height = gap * h;
for (var y = 0; y < height; y += gap) {
for (var x = 0; x < width; x += gap) {
dots.push(
new S.Point({
x: x,
y: y,
})
);
}
}
return {
dots: dots,
w: width,
h: height
};
},
};
})();
S.Shape = (function() {
var dots = [],
width = 0,
height = 0,
cx = 0,
cy = 0;
function compensate() {
var a = S.Drawing.getArea();
cx = a.w / 2 - width / 2;
cy = a.h / 2 - height / 2;
}
return {
shuffleIdle: function() {
var a = S.Drawing.getArea();
for (var d = 0; d < dots.length; d++) {
if (!dots[d].s) {
dots[d].move({
x: Math.random() * a.w,
y: Math.random() * a.h,
});
}
}
},
switchShape: function(n, fast) {
var size,
a = S.Drawing.getArea();
width = n.w;
height = n.h;
compensate();
if (n.dots.length > dots.length) {
size = n.dots.length - dots.length;
for (var d = 1; d <= size; d++) {
dots.push(new S.Dot(a.w / 2, a.h / 2));
}
}
var d = 0,
i = 0;
while (n.dots.length > 0) {
i = Math.floor(Math.random() * n.dots.length);
dots[d].e = fast ? 0.25 : dots[d].s ? 0.14 : 0.11;
if (dots[d].s) {
dots[d].move(
new S.Point({
z: Math.random() * 20 + 10,
a: Math.random(),
h: 18,
})
);
} else {
dots[d].move(
new S.Point({
z: Math.random() * 5 + 5,
h: fast ? 18 : 30,
})
);
}
dots[d].s = true;
dots[d].move(
new S.Point({
x: n.dots[i].x + cx,
y: n.dots[i].y + cy,
a: 1,
z: 5,
h: 0,
})
);
n.dots = n.dots.slice(0, i).concat(n.dots.slice(i + 1));
d++;
}
for (var i = d; i < dots.length; i++) {
if (dots[i].s) {
dots[i].move(
new S.Point({
z: Math.random() * 20 + 10,
a: Math.random(),
h: 20,
})
);
dots[i].s = false;
dots[i].e = 0.04;
dots[i].move(
new S.Point({
x: Math.random() * a.w,
y: Math.random() * a.h,
a: 0.3, //.4
z: Math.random() * 4,
h: 0,
})
);
}
}
},
render: function() {
for (var d = 0; d < dots.length; d++) {
dots[d].render();
}
},
};
})();
S.init();