Canvas绘制地板

2017-03-16 本文已影响35人 Cesium4Unreal

导语

随着数据中心可视化系统的要求越来越高，2D、3D效果都要求几乎逼真；3D地板，相较于2D，实为更易，只需引擎(如：twaver.js、three.js等),外加一张地板图片，便可实现；本文重点介绍如何使用2D绘制地板、以及如何做出伪3D的地板效果；

先睹为快

2D机房地板

伪3D机房地板

木制地板

若有所思

看到如上效果，你也许会嘲笑鄙人；这样的效果，一张图片就解决，何以兴师动众，大动干戈；然，若您知道，房间地板的形状、材质参差不齐，如何一张图片能解决，你是否理解了我的所作所为，所思所想呢？

这样地板见过吗？

花花世界地板

木板材质

大理石地板

如你所想，这样给出地板材质和坐标信息，便很容易呈现形形状状的地板了，具体是如何实现的呢？

实验天地

Canvas

HTML5的Canvas标签，应该无需赘言, 若您对此不解，请移步Canvas.

"给我一张Canvas，还你你个精彩世界"；--世界著名学者Canvas

createPattern

The CanvasRenderingContext2D
**.createPattern()

** method of the Canvas 2D API creates a pattern using the specified image (a CanvasImageSource
). It repeats the source in the directions specified by the repetition argument. This method returns a CanvasPattern
.

image
A CanvasImageSource
to be used as image to repeat. It can either be a:

HTMLImageElement

HTMLVideoElement

HTMLCanvasElement

CanvasRenderingContext2D

ImageBitmap

Blob

repetition

A DOMString
indicating how to repeat the image. Possible values are:

"repeat" (both directions),

"repeat-x" (horizontal only),

"repeat-y" (vertical only), or

"no-repeat" (neither).

If repetition is an empty string ('') or null
(but not undefined
), repetition will be "repeat".

Example
<pre>
<canvas id="canvas"></canvas>
</pre>
<pre>
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');

var img = new Image();
img.src = 'https://mdn.mozillademos.org/files/222/Canvas_createpattern.png';
img.onload = function() {
var pattern = ctx.createPattern(img, 'repeat');
ctx.fillStyle = pattern;
ctx.fillRect(0, 0, 400, 400);
};
</pre>

实验结果

是不是非常的简单，正如API所言，可以支持图片、Canvas、Vedio、Blob等等，因此，我们可以在Canvas上自己绘制地板样式，再用于填充，起步完美！

填充Canvas内容

<pre>
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
function init() {
var canvas = document.getElementById("bg");
var ctx = canvas.getContext("2d");

        var tile = document.createElement('canvas');
        tile.width = 50;
        tile.height = 50;
        var tileCtx = tile.getContext("2d");
        draw(tileCtx);
        var objPattern = ctx.createPattern(tile, "repeat");
        ctx.rotate(-(Math.PI / 180) * 25);
        ctx.fillStyle = objPattern;
        ctx.fillRect(50, 300,700,400);
    }

    function draw(tileCtx) {
        var translator = new Translator3D({x:0,y:0,width:50,height:50});
        tileCtx.save();
        tileCtx.beginPath();
        tileCtx.strokeStyle = 'rgba(100,100,0,1)';      
        var point  = {x:0,y:25};
        // point = translator.translate(point.x,point.y);
        tileCtx.moveTo(point.x, point.y);
        var point  = {x:50,y:25};
        // point = translator.translate(point.x,point.y);
        tileCtx.lineTo(point.x, point.y);
        var point  = {x:25,y:0};
        // point = translator.translate(point.x,point.y);
        tileCtx.moveTo(point.x, point.y);
        var point  = {x:25,y:50};
        // point = translator.translate(point.x,point.y);
        tileCtx.lineTo(point.x, point.y);
        
        tileCtx.stroke();
        tileCtx.restore();
    }
</script>

</head>
<body onload="init();">
<canvas id="bg" width="1000" height="500" ></canvas>
</body>
</html>
</pre>

刷Canvas内容

写到这，应该是对此技术应该非常熟练了，若想做出开篇的效果图，添加自己的创造，很容易便可实现；

参考资料

[1].HTML5，不只是看上去很美（第二弹：打造最美3D机房）
[2].CanvasRenderingContext2D.createPattern
[3].Canvas