Canvas实现的一个壁纸demo
原创
实现的效果见我发布的视频
这个壁纸我好像是在csdn里首先看到的 觉得非常有意思，所以自己实现了一个。
先直接上代码吧，直接用原生js实现，因此直接用浏览器打开就可以看到效果，非常的方便。
! function() {
function SetCanvasArea() {
CanvasWidth = canvas.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
CanvasHeight = canvas.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
}
function RefreshCanvas() {
canvas2D.clearRect(0, 0, CanvasWidth, CanvasHeight);
canvas2D.fillStyle = "#2473ab";
canvas2D.fillRect(0, 0, CanvasWidth, CanvasHeight);
canvas2D.fillStyle = "rgb(255,248,220)";
var AllNodeList = [MouseCoor].concat(NodeList);
var NodeV, LineWidth, DistanceX, DistanceY, Distance;
NodeList.forEach(function(NodeI) {
NodeI.x += NodeI.DX;
NodeI.y += NodeI.DY;
NodeI.DX *= (NodeI.x > CanvasWidth || NodeI.x < 0) ? -1 : 1;
NodeI.DY *= (NodeI.y > CanvasHeight || NodeI.y < 0) ? -1 : 1;
canvas2D.fillRect(NodeI.x - 0.5, NodeI.y - 0.5, 1, 1);
for (var v = 0; v < AllNodeList.length; v++) {
NodeV = AllNodeList[v];
if (NodeI !== NodeV && null !== NodeV.x && null !== NodeV.y) {
DistanceX = NodeI.x - NodeV.x;
DistanceY = NodeI.y - NodeV.y;
Distance = DistanceX * DistanceX + DistanceY * DistanceY;
if (Distance < NodeV.max) {
if (NodeV === MouseCoor && Distance >= NodeV.max / 2) {
NodeI.x -= 0.03 * DistanceX;
NodeI.y -= 0.03 * DistanceY;
}
canvas2D.strokeStyle = "rgb(255,248,220)";
LineWidth = (NodeV.max - Distance) / NodeV.max;
canvas2D.beginPath(), canvas2D.lineWidth = LineWidth / 2;
canvas2D.moveTo(NodeI.x, NodeI.y), canvas2D.lineTo(NodeV.x, NodeV.y);
canvas2D.stroke();
}
}
}
AllNodeList.splice(AllNodeList.indexOf(NodeI), 1);
});
RequestAnimationFrame(RefreshCanvas);
}
var canvas = document.createElement("canvas"),
canvas2D = canvas.getContext("2d"),
CanvasWidth,
CanvasHeight,
NodeList,
RequestAnimationFrame = window.requestAnimationFrame,
RandomNumber = Math.random,
MouseCoor = { x: null, y: null, max: 20000 };
canvas.id = "demo";
canvas.style.cssText = "position:fixed;top:0;left:0;z-index:-1;opacity:0.5";
canvas2D.fillStyle = "#2473ab";
canvas2D.fillRect(0, 0, CanvasWidth, CanvasHeight);
document.getElementsByTagName("body")[0].appendChild(canvas);
SetCanvasArea();
window.onresize = SetCanvasArea;
window.onmousemove = function(i) {
i = i || window.event;
MouseCoor.x = i.clientX;
MouseCoor.y = i.clientY;
};
window.onmouseout = function() {
MouseCoor.x = null;
MouseCoor.y = null;
};
for (NodeList = [], p = 0; 200 > p; p++) {
var NodeX = RandomNumber() * CanvasWidth,
NodeY = RandomNumber() * CanvasHeight,
NodeDX = 2 * RandomNumber() - 1,
NodeDY = 2 * RandomNumber() - 1;
NodeList.push({ x: NodeX, y: NodeY, DX: NodeDX, DY: NodeDY, max: 6000 });
}
setTimeout(function() {
RefreshCanvas();
}, 0);
}();在html中直接引入即可
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="utf-8">
<title>demo</title>
<body>
<script type="text/javascript" src="./demo.js"></script>
</body>
</html>简单解释下代码：
首先我们需要一些在屏幕中漂移的点，如果想要线密集一些也可以把点的数量加多。X,Y表示点的坐标，DX DY表示点的漂移速度，max表示当其他点与该点的距离小于该值时，则与该点连线。
for (NodeList = [], p = 0; 200 > p; p++) {
var NodeX = RandomNumber() * CanvasWidth,
NodeY = RandomNumber() * CanvasHeight,
NodeDX = 2 * RandomNumber() - 1,
NodeDY = 2 * RandomNumber() - 1;
NodeList.push({ x: NodeX, y: NodeY, DX: NodeDX, DY: NodeDY, max: 6000 });
}一个坐标对象MouseCoor用于储存鼠标的位置。
RefreshCanvas函数用于实现上面说的连线规则：
遍历所有漂移的点NodeList；
另外注意：当DX,DY碰到边界时，将重置DX,DY的方向，这里为了方便设置为1/-1，如果有强迫症将DX置为-DX效果也是一样的。
NodeI.DX *= (NodeI.x > CanvasWidth || NodeI.x < 0) ? -1 : 1;
NodeI.DY *= (NodeI.y > CanvasHeight || NodeI.y < 0) ? -1 : 1;与加上鼠标在内的其他点进行连线判定
for (var v = 0; v < AllNodeList.length; v++) {
NodeV = AllNodeList[v];
if (NodeI !== NodeV && null !== NodeV.x && null !== NodeV.y) {
DistanceX = NodeI.x - NodeV.x;
DistanceY = NodeI.y - NodeV.y;
Distance = DistanceX * DistanceX + DistanceY * DistanceY;
if (Distance < NodeV.max) {
if (NodeV === MouseCoor && Distance >= NodeV.max / 2) {
NodeI.x -= 0.03 * DistanceX;
NodeI.y -= 0.03 * DistanceY;
}
canvas2D.strokeStyle = "rgb(255,248,220)";
LineWidth = (NodeV.max - Distance) / NodeV.max;
canvas2D.beginPath(), canvas2D.lineWidth = LineWidth / 2;
canvas2D.moveTo(NodeI.x, NodeI.y), canvas2D.lineTo(NodeV.x, NodeV.y);
canvas2D.stroke();
}
}
}最后再加上循环
RequestAnimationFrame(RefreshCanvas);这样一个简单的壁纸demo就完成了，并且效果也非常好，反正我第一次见到还感觉挺好玩的点了半天。
后面我也将这个壁纸移植到了微信小游戏中实现。下次发微信小程序的实现代码。
原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。
如有侵权，请联系 cloudcommunity@tencent.com 删除。
原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。
如有侵权，请联系 cloudcommunity@tencent.com 删除。
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