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<svg id="cloud" width="800" height="70"></svg>
<svg id="wave" width="800" height="360">
</svg>
<button id="weather">切换天气</button>
body{
padding:0;margin:0;}
#cloud{
position: absolute;
left: 50%;
margin-left: -400px;
}
#wave{
margin:0 auto;
display: block;
}
/**
* 作者: luxueyan
* 博客: http://hi.gitcafe.io
* 参考: http://gamedev.stackexchange.com/questions/44547/2d-water-with-dynamic-waves
* 注: 原文包含lua和prosessing.js
*/
var s = Snap('#wave');
//波预设
var wave = s.paper.path('').attr({
stroke: 'Cyan',
fill: 'Cyan'
});
//雨滴
// var rains = makeRains();
//河岸
var bank = s.paper.path('M50 150 H100 V350H700V150H750').attr({
stroke: 'silver',
strokeWidth: 5,
fill: 'none',
strokeLinejoin: 'round'
});
var lastUpdate = +new Date;
// rain count
var RAIN_COUNT = 6;
// Resolution of simulation
var NUM_POINTS = 180;
// Width of simulation
var WIDTH = 600;
// Horizonal Position
var X_OFFSET = 100;
// Spring constant for forces applied by adjacent points
var SPRING_CONSTANT = 0.005;
// Sprint constant for force applied to baseline
var SPRING_CONSTANT_BASELINE = 0.005;
// Vertical draw offset of simulation
var Y_OFFSET = 200;
// Damping to apply to speed changes
var DAMPING = 0.99;
// Number of iterations of point-influences-point to do on wave per step
// (this makes the waves animate faster)
var ITERATIONS = 5;
// A phase difference to apply to each sine
var offset = 0;
var NUM_BACKGROUND_WAVES = 7;
var BACKGROUND_WAVE_MAX_HEIGHT = 5;
var BACKGROUND_WAVE_COMPRESSION = 1 / 10;
// Amounts by which a particular sine is offset
var sineOffsets = [];
// Amounts by which a particular sine is amplified
var sineAmplitudes = [];
// Amounts by which a particular sine is stretched
var sineStretches = [];
// Amounts by which a particular sine's offset is multiplied
var offsetStretches = [];
// Set each sine's values to a reasonable random value
var tableContent = "";
var rainState;
var wavePoints = makeWavePoints(NUM_POINTS);
function init() {
for (var i = -0; i < NUM_BACKGROUND_WAVES; i++) {
var sineOffset = -Math.PI + 2 * Math.PI * Math.random();
sineOffsets.push(sineOffset);
var sineAmplitude = Math.random() * BACKGROUND_WAVE_MAX_HEIGHT;
sineAmplitudes.push(sineAmplitude);
var sineStretch = Math.random() * BACKGROUND_WAVE_COMPRESSION;
sineStretches.push(sineStretch)
var offsetStretch = Math.random() * BACKGROUND_WAVE_COMPRESSION;
offsetStretches.push(offsetStretch);
}
//cloud
var c = Snap('#cloud');
c.paper.path('M100.063,20c0,0-49.649-28.854,85.269-19.895c31.768-24.37,130.412-9.946,130.412-9.946c42.981-8.315,170.958-20.393,147.551,13.429c-8.247,11.914,38.582-3.945,57.264,8.454c30.454,20.216,2.868,23.573-44.308,23.252c-30.094,9.155-41.798,4.974-41.798,4.974c-75.237,14.051-29.94-6.469-96.172,1.119c-56.335,6.454-48.23,0.885-134.444,0.688c-81.296-0.184-53.616-6.159-80.366-7.154c2.579,9.812,-5.063,-6.227,-10.063,-10.227z').attr({stroke:'#A7A9AC', fill:"#A7A9AC"});
c.paper.path('M280.063,20c0,0-49.649-28.854,85.269-19.895c31.768-24.37,130.412-9.946,130.412-9.946c42.981-8.315,170.958-20.393,147.551,13.429c-8.247,11.914,38.582-3.945,57.264,8.454c30.454,20.216,2.868,23.573-44.308,23.252c-30.094,9.155-41.798,4.974-41.798,4.974c-75.237,14.051-29.94-6.469-96.172,1.119c-56.335,6.454-48.23,0.885-134.444,0.688c-81.296-0.184-53.616-6.159-80.366-7.154c2.579,9.812,-5.063,-6.227,-10.063,-10.227z').attr({stroke:'#A7A9AC', fill:"#A7A9AC"});
}
// Make points to go on the wave
function makeWavePoints(numPoints) {
var t = [];
for (var n = 0; n < numPoints; n++) {
// This represents a point on the wave
var newPoint = {
x: n / numPoints * WIDTH + X_OFFSET,
y: Y_OFFSET,
spd: {
y: 0
}, // speed with vertical component zero
mass: 1
}
t.push(newPoint);
}
return t
}
// This function sums together the sines generated above,
// given an input value x
function overlapSines(x) {
var result = 0;
for (var i = 0; i < NUM_BACKGROUND_WAVES; i++) {
result = result + sineOffsets[i] + sineAmplitudes[i] * Math.sin(x * sineStretches[i] + offset * offsetStretches[i]);
}
return result;
}
// Update the positions of each wave point
function updateWavePoints(points, dt) {
for (var i = 0; i < ITERATIONS; i++) {
for (var n = 0; n < points.length; n++) {
var p = points[n];
// force to apply to this point
var force = 0;
// forces caused by the point immediately to the left or the right
var forceFromLeft, forceFromRight;
if (n == 0) { // wrap to left-to-right
var dy = points[points.length - 1].y - p.y;
forceFromLeft = SPRING_CONSTANT * dy;
} else { // normally
var dy = points[n - 1].y - p.y;
forceFromLeft = SPRING_CONSTANT * dy;
}
if (n == points.length - 1) { // wrap to right-to-left
var dy = points[0].y - p.y;
forceFromRight = SPRING_CONSTANT * dy;
} else { // normally
var dy = points[n + 1].y - p.y;
forceFromRight = SPRING_CONSTANT * dy;
}
// Also apply force toward the baseline
var dy = Y_OFFSET - p.y;
forceToBaseline = SPRING_CONSTANT_BASELINE * dy;
// Sum up forces
force = force + forceFromLeft;
force = force + forceFromRight;
force = force + forceToBaseline;
// Calculate acceleration
var acceleration = force / p.mass;
// Apply acceleration (with damping)
p.spd.y = DAMPING * p.spd.y + acceleration;
// Apply speed
p.y = p.y + p.spd.y;
}
}
}
// Callback for drawing
function drawWave(dt) {
offset = offset + 1;
// Update positions of points
updateWavePoints(wavePoints, dt)
var path = [];
//构造路径
for (var n = 0; n < wavePoints.length; n++) {
var p = wavePoints[n];
if (n == 0) {
path.push('M' + p.x + ' ' + (p.y + overlapSines(p.x, 0, 0)));
} else {
path.push(p.x + ' ' + (p.y + overlapSines(p.x)));
}
}
path.push('V350H100V150');
wave.attr({
path: path
});
}
//make rains
function makeRains() {
var rains = [];
for (var n = 0; n < RAIN_COUNT; n++) {
rains.push([X_OFFSET + WIDTH * Math.random(), 50 * Math.random(), 1, 3]);
}
return rains;
}
//获取雨点对应点的index
function getClosestPointIndex(cx) {
var left = parseInt((cx - X_OFFSET) / (WIDTH / NUM_POINTS) - 1);
return left + (Math.abs(wavePoints[left].x - cx) > Math.abs(wavePoints[left + 1].x - cx));
// var high = NUM_POINTS - 1;
// var low = 0;
// var mid = 0;
// var index, x;
// while (low <= high) {
// mid = parseInt((high + low)/2);
// x = wavePoints[mid].x;
// if (x == cy) {
// index = mid;
// break;
// } else if (high - low = 1) {
// index = Math.abs(wavePoints[high].x - cy) > Math.abs(wavePoints[low].x - cy) ? high : low;
// break;
// } else if (x > cy) {
// high = mid - 1;
// } else if (x < cy) {
// low = mid + 1;
// }
// }
// return index;
}
function updateRains(now) {
var rains = s.selectAll('ellipse');
rains.forEach(function(e, i) {
var cx = parseInt(e.attr('cx'));
var closestPointIndex = parseInt(e.attr('data-cp-index'));
var cy = parseInt(e.attr('data-start-y')) + 0.5 * Math.pow((now - parseInt(e.attr('data-start-time'))) / 50, 2);
if (wavePoints[closestPointIndex].y <= cy) {
wavePoints[closestPointIndex].y = Y_OFFSET + 10;
e.remove();
} else {
e.attr({
cy: cy
});
}
});
}
function drawRains() {
var rains = makeRains();
var l = rains.length;
// var g = s.g();
var now = +new Date;
for (var n = 0; n < l; n++) {
s.paper.ellipse(rains[n][0], rains[n][1], rains[n][2], rains[n][3]).attr({
'data-start-time': now,
'fill': 'Cyan',
'data-cp-index': getClosestPointIndex(rains[n][0]),
'data-start-y': rains[n][1]
});
}
rainState = 'on';
}
function run() {
var now = +new Date;
var dt = now - lastUpdate;
lastUpdate = now;
drawWave(dt);
updateRains(now);
}
var rainHd = setInterval(drawRains, 500);
init();
//begin run
var runHd = setInterval(function() {
run();
}, 30);
$('#weather').click(function(){
if(rainState == 'on') {
clearInterval(rainHd);
rainState = 'off';
} else {
rainHd = setInterval(drawRains, 500);
}
});
Also see: Tab Triggers