我正在为大学制作一个小游戏，我需要在我的项目中添加不同的形状。我说的是三角形、矩形、五边形、六边形、七边形、八边形……n-gon。我需要所有的形状都是凸正多边形并且能够为内部着色。我正在考虑绘制 SVG 形状，但我不确定应该只在要生成的形状的 n 侧给出什么公式。如果有一个 JS 插件可以包含在 Bower 中并生成形状，那就太好了。还有一个问题是给它们上色，然后可以用动画改变颜色，但要一步一步来。
【问题讨论】：
标签： javascript html css svg shapes
以下是我用来构建多边形的方法。它提供随机填充颜色。看看这是否有帮助。
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Create SVG Polygons</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body style='padding:10px;font-family:arial'>
<center>
<h4>Create SVG Polygons</h4>
<div style='width:90%;background-color:gainsboro;text-align:justify;padding:10px;border-radius:6px;'>
Create inline svg with random circles, ellipses, polygons, and rectangles used for test environment.
</div><br />
<div id="svgDiv" style='border:1px black outset'>
<svg id="mySVG" />
</div><br />
Number Of Elements:<input type=text id=elemsValue size=1 value=1200 />
SVG Width:<input type=text id=widthValue size=1 value=600 />
SVG Height:<input type=text id=heightValue size=1 value=400 />
Element Sze:<input type=text id=sizeValue size=1 value=20 />
<button onClick=go()>go</button><br />
<script>
//---button---
function go()
{
var elems=parseInt(elemsValue.value)
var svgWidth=parseFloat(widthValue.value)
var svgHeight=parseFloat(heightValue.value)
var elemSize=parseFloat(sizeValue.value)
//---clear prevoius---
mySVG.removeChild(document.getElementById("globG"))
svgGLOB(elems,svgWidth,svgHeight,elemSize)
}
function svgGLOB(elems,svgWidth,svgHeight,elemSize)
{
/* ---fill empty inline SVG element---
<div id="svgDiv"><svg id="mySVG" /></div>
*/
var NS="http://www.w3.org/2000/svg"
mySVG.setAttribute("width",svgWidth)
mySVG.setAttribute("height",svgHeight)
svgDiv.style.width=svgWidth+"px"
svgDiv.style.height=svgHeight+"px"
var globG=document.createElementNS(NS,"g")
globG.id="globG"
globG.setAttribute("stroke","black")
globG.setAttribute("stroke-width",1)
mySVG.appendChild(globG)
var points=randomPoints(elems,svgWidth,svgHeight,elemSize)
var n=points.length
var circleCnt=0
var ellipseCnt=0
var rectCnt=0
var polygonCnt=0
var RandomElems=[]
RandomElems[0]="circle"
RandomElems[1]="rect"
RandomElems[2]="ellipse"
RandomElems[3]="polygon_3"
RandomElems[4]="polygon_4"
RandomElems[5]="polygon_5"
RandomElems[6]="polygon_6"
RandomElems[7]="polygon_7"
RandomElems[8]="polygon_8"
RandomElems[9]="polygon_9"
RandomElems[10]="polygon_10"
RandomElems[11]="polygon_11"
RandomElems[12]="polygon_12"
for(var k=0;k<n;k++)
{
var rand=rdm(0,12)
var elemStr=RandomElems[rand]
if(!elemStr.indexOf("_"))
var elemSt=elemStr
else
var elemSt=elemStr.split("_")[0]
var elem=document.createElementNS(NS,elemSt)
if(elemSt=="circle")
{
elem.setAttribute("r",elemSize)
elem.setAttribute("fill",rcolor())
elem.setAttribute("cx",points[k][0])
elem.setAttribute("cy",points[k][1])
elem.id=elemSt+(circleCnt++)
}
else if(elemSt=="ellipse")
{
elem.setAttribute("rx",elemSize)
elem.setAttribute("ry",elemSize/2)
elem.setAttribute("fill",rcolor())
elem.setAttribute("cx",points[k][0])
elem.setAttribute("cy",points[k][1])
elem.id=elemSt+(ellipseCnt++)
}
else if(elemSt=="rect")
{
elem.setAttribute("width",elemSize)
elem.setAttribute("height",elemSize)
elem.setAttribute("fill",rcolor())
elem.setAttribute("x",points[k][0])
elem.setAttribute("y",points[k][1])
elem.id=elemSt+(rectCnt++)
}
else if(elemSt=="polygon")
{
var pgonSides=parseInt(elemStr.split("_")[1])
var pgonPnts=polygon(pgonSides,elemSize,points[k][0],points[k][1])
elem.setAttribute("fill",rcolor())
elem.setAttribute("points",pgonPnts.join())
elem.id=elemSt+(polygonCnt++)
}
globG.appendChild(elem)
}
//---obtain a random whole number from a thru b---
function rdm(a,b)
{
return a + Math.floor(Math.random()*(b-a+1));
}
function randomPoints(elems,svgWidth,svgHeight,elemSize)
{
//--return format:[ [x,y],[x,y],,, ]
//---Generate random points---
function times(n, fn)
{
var a = [], i;
for (i = 0; i < n; i++) {
a.push(fn(i));
}
return a;
}
var width=svgWidth-2*elemSize
var height=svgHeight-2*elemSize
return RandomPnts = times(elems, function() { return [Math.floor(width * Math.random()) + elemSize, Math.floor(height * Math.random()) + elemSize] });
}
//---random color---
function rcolor()
{
var letters = '0123456789ABCDEF'.split('');
var color = '#';
for (var i = 0; i < 6; i++ )
{
color += letters[Math.round(Math.random() * 15)];
}
return color;
}
function polygon(vCnt,radius,centerX,centerY)
{
var myPoints=[]
var polyXPts = Array(vCnt);
var polyYPts = Array(vCnt);
var vertexAngle = 360/vCnt;
//---init polygon points processor---
for(var v=0; v<vCnt; v++)
{
theAngle = (v*vertexAngle)*Math.PI/180;
polyXPts[v] = radius*Math.cos(theAngle);
polyYPts[v] = -radius*Math.sin(theAngle);
}
//--note points are CCW---
for(var v=0;v<vCnt; v++)
{
var point=[centerX+polyXPts[v],centerY+polyYPts[v]]
myPoints.push(point)
}
return myPoints
}
}
document.addEventListener("onload",init(),false)
function init()
{
svgGLOB(1200,600,400,20)
}
</script>
</body>
</html>【讨论】：
elem.style.transform = 'rotate('+deg+'deg)'; elem.style.transformOrigin = '50% 50%';，但是如何计算每个n-gon的具体度数？