JavaScript 八卦

曾经终败给现在 2022-07-12 12:37 94阅读 0赞

<html>
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            <meta charset="utf8" />
            <title>伏羲八卦</title>
            <style type="text/css"> #canvas { background-color:yellow; } </style>
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        <body>
            <canvas id="canvas" width="950" height="950">This browser does not support canvas tag</canvas>
            <script type="text/javascript"> var c = document.getElementById("canvas"); var ctx = c.getContext("2d"); //太极中心点X坐标 var centerX = c.width / 2; //太极中心点Y坐标 var centerY = c.height / 2; //阴阳鱼(左阳右阴)形环转相抱的太极图的半径,大圈通神 var radius = 200; //鱼头半径,中圈通气 var fishHeadRadius = radius / 2; //鱼眼半径,小圈养精 var fisheyeRadius = radius / 6; //当前弧度数(从0点钟方向为起始,顺时针方向为正,初始图像为左阳右阴) var radian = 0; //2 * Math.PI弧度切割的总份数 var radianCount = 720; //2 * Math.PI长度,避免重复计算 var doublePI = Math.PI * 2; var halfPI = Math.PI * 0.5; //弧度步长 var radianStep = doublePI / radianCount; //八卦间隔弧度 var eightCombinationRadiusStep = doublePI / 8; //八卦间隔弧度的一半 var eightCombinationRadiusHalfStep = doublePI / 16; var sinEightCombinationRadiusHalfStep = Math.sin(eightCombinationRadiusHalfStep); var cosEightCombinationRadiusHalfStep = Math.cos(eightCombinationRadiusHalfStep); //八卦内径 var eightCombinationInnerDiameter = radius + 0; //八卦的正八边形的外切圆半径 var eightCombinationOutsideDiameter = eightCombinationInnerDiameter + 150; //八卦的正八边形边框线宽 var eightCombinationRegularOctagonLineWidth = 15; //八卦内径到正八边形的最短距离 var eightCombinationInnerDiameterToRegularOctagonDistance = (eightCombinationOutsideDiameter - eightCombinationRegularOctagonLineWidth / 2) * cosEightCombinationRadiusHalfStep - eightCombinationInnerDiameter; //八卦线断开的间隔 var eightCombinationLineBreakLength = 15; //八卦线宽 var eightCombinationLineWidth = eightCombinationInnerDiameterToRegularOctagonDistance / 7; //八卦线两端与圆心连成的三角形在圆心处的弧度的一半 var eightCombinationLineHalfTriangleRadius = new Float32Array(3); //八卦线两端到圆心的距离 var eightCombinationLineEndRadius = new Float32Array(3); //八卦线条类型(外0x04,中0x02,内0x01; 1表示完整,0表示中间断开) //var eightCombinationLineTypes = new Uint8Array([111,110,010,100,000,001,101,011]); var eightCombinationLineTypes = new Uint8Array([7,6,2,4,0,1,5,3]); //初始化八卦线数据 function initEightCombinationLine() { //八卦线长(二分之一的外框长) var eightCombinationLineLength = eightCombinationOutsideDiameter * sinEightCombinationRadiusHalfStep; //内径到八卦线,再到正八边形的距离比例 var distanceRates = [1.5, 3.5, 5.5]; for(var i=0; i<3; i++) { var eightCombinationLineCenterRadius = eightCombinationInnerDiameter + eightCombinationLineWidth * distanceRates[i]; eightCombinationLineHalfTriangleRadius[i] = Math.atan(eightCombinationLineLength / 2 / eightCombinationLineCenterRadius); eightCombinationLineEndRadius[i] = eightCombinationLineCenterRadius / Math.cos(eightCombinationLineHalfTriangleRadius[i]); } } //辅助线宽 var auxiliaryLineWidth = 1; //八卦字体 var eightCombinationFont = "bold 22pt 'Microsoft YaHei',SimHei,FangSong,KaiTi,YouYuan blue"; //八卦字体颜色 var eightCombinationFontColor = "black"; //八卦方位文字的半径 var eightCombinationDirectionTextRadius = eightCombinationOutsideDiameter + 20; //八卦文字的半径 var eightCombinationTextRadius = eightCombinationDirectionTextRadius + 40; //八卦宫号 var eightCombinationNumRadius = eightCombinationTextRadius + 40; //八卦方向文字 var eightCombinationDirectionTexts = ["南","西南","西","西北","北","东北","正","东南",]; //八卦文字 var eightCombinationTexts = ["乾(天)","巽xun(风)","坎(水)","艮gen(山)","坤(地)","震(雷)","离(火)","兑(沼泽)",]; //八卦宫号 var eightCombinationNums = ["一","五","六","七","八","四","三","二","一",]; //阳鱼鱼眼X坐标 var whiteFisheyeX; //阳鱼鱼眼Y坐标 var whiteFisheyeY; //阴鱼鱼眼X坐标 var blackFisheyeX; //阴鱼鱼眼Y坐标 var blackFisheyeY; //画弧 function fillArc(cx, cy, r, startRadian, endRadian, color) { ctx.fillStyle = color; ctx.beginPath(); ctx.arc(cx, cy, r, startRadian, endRadian); ctx.fill(); } //描圆 function strokeCircle(cx, cy, r, color, lineWidth) { ctx.fillStyle = color; ctx.lineWidth = lineWidth; ctx.beginPath(); ctx.arc(cx, cy, r, 0, doublePI); ctx.stroke(); } //绘制经过圆心的直径 function strokeCircleDiameter(cx, cy, r, rad, color, lineWidth) { ctx.strokeStyle = color; ctx.lineWidth = lineWidth var sinRad = Math.sin(rad); var cosRad = Math.cos(rad); ctx.beginPath(); ctx.moveTo(cx + r * sinRad, cy - r * cosRad); ctx.lineTo(cx - r * sinRad, cy + r * cosRad) ctx.stroke(); } //在圆上绘制文字 function fillCircleText(cx, cy, r, rad, color, font, text) { ctx.fillStyle = color; ctx.font = font; ctx.textAlign = "center"; ctx.fillText(text, cx + r * Math.sin(rad), cy - r * Math.cos(rad)); } //绘制八卦的某一条线 function strokeEightCombination(cx, cy, r, rad, halfTriangleRad, color, lineWidth, isBreak, breakLength) { ctx.strokeStyle = color; ctx.lineWidth = lineWidth; var rad1 = rad - halfTriangleRad; var rad2 = rad + halfTriangleRad; var x1 = cx + r * Math.sin(rad1); var y1 = cy - r * Math.cos(rad1); var x2 = cx + r * Math.sin(rad2); var y2 = cy - r * Math.cos(rad2); ctx.beginPath(); ctx.moveTo(x1, y1); if(isBreak !== undefined && isBreak === true && breakLength !== undefined && breakLength > 0) { //这里不能用"向量夹角公式": con(@) = b*c/(|b|*|c|)来求夹角,因为同一个cos值有两个角与之对应 //因此这里要用相似三角形公式 var midX = (x1 + x2) / 2; var midY = (y1 + y2) / 2; var dx = x2 - x1; var dy = y2 - y1; var len = Math.sqrt(Math.pow(dx, 2) + Math.pow(dy, 2)); var halfBreakPercentage = breakLength / len / 2; var halfBreakX = dx * halfBreakPercentage; var halfBreakY = dy * halfBreakPercentage; var midX1 = midX - halfBreakX; var midY1 = midY - halfBreakY; var midX2 = midX + halfBreakX; var midY2 = midY + halfBreakY; ctx.lineTo(midX1, midY1); ctx.moveTo(midX2, midY2); } ctx.lineTo(x2, y2); ctx.stroke(); } //更新 function update() { //radian = 0; radian += radianStep; if(radian >= doublePI) { radian = 0; } whiteFisheyeX = centerX + fishHeadRadius * Math.sin(radian); whiteFisheyeY = centerY - fishHeadRadius * Math.cos(radian); blackFisheyeX = centerX - fishHeadRadius * Math.sin(radian); blackFisheyeY = centerY + fishHeadRadius * Math.cos(radian); } //渲染 function render() { ctx.clearRect(0, 0, c.width, c.height); var rad; //八卦外边框 ctx.lineWidth = eightCombinationRegularOctagonLineWidth; ctx.fillStyle = "black"; ctx.beginPath(); rad = radian - eightCombinationRadiusHalfStep; for(var i=0; i < 8; i++, rad += eightCombinationRadiusStep) { if(i == 0) { ctx.moveTo(centerX + eightCombinationOutsideDiameter * Math.sin(rad), centerY - eightCombinationOutsideDiameter * Math.cos(rad)); } else { ctx.lineTo(centerX + eightCombinationOutsideDiameter * Math.sin(rad), centerY - eightCombinationOutsideDiameter * Math.cos(rad)); } } ctx.closePath(); ctx.stroke(); //八卦分隔线 rad = radian - eightCombinationRadiusHalfStep; for(var i = 0; i < 4; i++, rad += eightCombinationRadiusStep) { strokeCircleDiameter(centerX, centerY, eightCombinationOutsideDiameter, rad, "black", auxiliaryLineWidth); } //八卦内环 //strokeCircle(centerX, centerY, eightCombinationInnerDiameter, auxiliaryLineWidth, "black"); //八卦外环 //strokeCircle(centerX, centerY, eightCombinationOutsideDiameter, auxiliaryLineWidth, "black"); //阳鱼 fillArc(centerX, centerY, radius, halfPI + radian, Math.PI + halfPI + radian, "white"); //阴鱼 fillArc(centerX, centerY, radius, -1 * halfPI + radian, halfPI + radian, "black"); //阳鱼头 fillArc(whiteFisheyeX, whiteFisheyeY, fishHeadRadius, 0, doublePI, "white"); //阴鱼头 fillArc(blackFisheyeX, blackFisheyeY, fishHeadRadius, 0, doublePI, "black"); //阳鱼眼 fillArc(blackFisheyeX, blackFisheyeY, fisheyeRadius, 0, doublePI, "white"); //阴鱼眼 fillArc(whiteFisheyeX, whiteFisheyeY, fisheyeRadius, 0, doublePI, "black"); //八卦 rad = radian; for(var i=0; i < 8; i++, rad += eightCombinationRadiusStep) { for(var j=0; j<3; j++) { var isBreak = (eightCombinationLineTypes[i] & (1 << j)) === 0; strokeEightCombination(centerX, centerY, eightCombinationLineEndRadius[j], rad, eightCombinationLineHalfTriangleRadius[j], "black", eightCombinationLineWidth, isBreak, eightCombinationLineBreakLength); } } //八卦文字 ctx.save(); //ctx.translate把画布原点平移到(x,y) ctx.translate(centerX, centerY); //注意: 旋转的弧度是"画布"从要绘制的目标点旋转到原来的点的弧度,也可以说是原来的点旋转到目标点的相反数. ctx.rotate(radian - Math.PI); for(var i=0; i < 8; i++, ctx.rotate(eightCombinationRadiusStep)) { fillCircleText(0, 0, eightCombinationTextRadius, Math.PI, eightCombinationFontColor, eightCombinationFont, eightCombinationTexts[i]); fillCircleText(0, 0, eightCombinationDirectionTextRadius, Math.PI, eightCombinationFontColor, eightCombinationFont, eightCombinationDirectionTexts[i]); fillCircleText(0, 0, eightCombinationNumRadius, Math.PI, eightCombinationFontColor, eightCombinationFont, eightCombinationNums[i]); } ctx.restore(); } function loop() { update(); render(); window.requestAnimationFrame(loop); } function init() { initEightCombinationLine(); loop(); } init(); </script>
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![这里写图片描述][20170114202131515]

[20170114202131515]: /images/20220712/b5a8d13fb2a1443c973f48ef1cc6335d.png